• BJT behaviour at ridiculously low current levels

    From Piotr Wyderski@21:1/5 to All on Wed May 11 20:39:08 2022
    Hi,

    I am experimenting with ultra-low power ideas and I was able to simulate
    a 30Hz relaxation oscillator running at 45nA/1V. I am waiting for the
    delivery of high-value resistors, but the same oscillator with resistors
    scaled down 10x works on the bench and consumes ~380nA/3V/360Hz which is
    still pretty awesome.

    This real device has been made of BSS123/BSS84 operating in the
    subthreshold realm -- the highest AC p-p voltage I can observe is
    ~500mV. There is a lot of interesting papers on subthreshold mode, so it
    is all good.

    But, out of curiosity, I replaced the FETs with BC847C/BC857C and it
    appears to work (in LTSpice!) even better, with V_BE sort of 350mV.
    I admit, no prototype so far. I didn't expect this -- could you please
    you recommend me some good book/papers on BJTs operated at nA levels?
    I would like to learn the theory in a proper way, as inferring it from a
    SPICE behavioural model might not be the best way to go. For example, it
    looks like the beta is extremely high there, even exponential. Does this
    BJT mode have a googlable name?

    Best regards, Piotr

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  • From whit3rd@21:1/5 to Piotr Wyderski on Wed May 11 12:15:40 2022
    On Wednesday, May 11, 2022 at 11:39:29 AM UTC-7, Piotr Wyderski wrote:
    Hi,

    I am experimenting with ultra-low power ideas and I was able to simulate
    a 30Hz relaxation oscillator running at 45nA/1V.
    ...
    recommend me some good book/papers on BJTs operated at nA levels?
    I would like to learn the theory in a proper way, as inferring it from a SPICE behavioural model might not be the best way to go. For example, it looks like the beta is extremely high there, even exponential. Does this
    BJT mode have a googlable name?

    Alas, it's a region that has high dependence on collector leakage currents
    (and cosmic rays, etc). Some of the space-rated research does get into
    this, because radiation damage moves the effects into higher-current parts
    of the characteristic. Beta is 'high' because the collector leakage is adding to the external base wire's contribution. It takes negative base bias to get an 'off' state, through Rbb resistance (base spreading resistance).

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  • From John Larkin@21:1/5 to bombald@protonmail.com on Wed May 11 12:17:51 2022
    On Wed, 11 May 2022 20:39:08 +0200, Piotr Wyderski
    <bombald@protonmail.com> wrote:

    Hi,

    I am experimenting with ultra-low power ideas and I was able to simulate
    a 30Hz relaxation oscillator running at 45nA/1V. I am waiting for the >delivery of high-value resistors, but the same oscillator with resistors >scaled down 10x works on the bench and consumes ~380nA/3V/360Hz which is >still pretty awesome.

    This real device has been made of BSS123/BSS84 operating in the
    subthreshold realm -- the highest AC p-p voltage I can observe is
    ~500mV. There is a lot of interesting papers on subthreshold mode, so it
    is all good.

    But, out of curiosity, I replaced the FETs with BC847C/BC857C and it
    appears to work (in LTSpice!) even better, with V_BE sort of 350mV.
    I admit, no prototype so far. I didn't expect this -- could you please
    you recommend me some good book/papers on BJTs operated at nA levels?
    I would like to learn the theory in a proper way, as inferring it from a >SPICE behavioural model might not be the best way to go. For example, it >looks like the beta is extremely high there, even exponential. Does this
    BJT mode have a googlable name?

    Best regards, Piotr



    There is a niche of building oscillators that run at very low supply
    voltages, ballpark 10 mV. I think jfets do pretty good.

    A depletion PHEMT might be good too.

    --

    If a man will begin with certainties, he shall end with doubts,
    but if he will be content to begin with doubts he shall end in certainties. Francis Bacon

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  • From Piotr Wyderski@21:1/5 to John Larkin on Wed May 11 21:23:17 2022
    John Larkin wrote:

    There is a niche of building oscillators that run at very low supply voltages, ballpark 10 mV. I think jfets do pretty good.

    Yes, there are several interesting examples. The lowest voltage I know
    of is 20mV. But in this off-time research application related to the
    recent CeraCharge purchase I am trying to minimize current consumption,
    not voltage. It can stop oscillating at 1.2V, no problem with that. But
    if the current could be as low as 20nA, that would be something.

    Best regards, Piotr

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  • From John Larkin@21:1/5 to bombald@protonmail.com on Wed May 11 12:49:05 2022
    On Wed, 11 May 2022 21:23:17 +0200, Piotr Wyderski
    <bombald@protonmail.com> wrote:

    John Larkin wrote:

    There is a niche of building oscillators that run at very low supply
    voltages, ballpark 10 mV. I think jfets do pretty good.

    Yes, there are several interesting examples. The lowest voltage I know
    of is 20mV. But in this off-time research application related to the
    recent CeraCharge purchase I am trying to minimize current consumption,
    not voltage. It can stop oscillating at 1.2V, no problem with that. But
    if the current could be as low as 20nA, that would be something.

    Best regards, Piotr

    The AOE X-chapter book has some data on using BJTs at pA levels.
    Section 2x.9

    2N4401 holds up pretty well at Ic of 100 pA. I'd expect some very
    small RF transistors to be pretty good.



    --

    If a man will begin with certainties, he shall end with doubts,
    but if he will be content to begin with doubts he shall end in certainties. Francis Bacon

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  • From Phil Hobbs@21:1/5 to Piotr Wyderski on Wed May 11 17:04:37 2022
    Piotr Wyderski wrote:
    Hi,

    I am experimenting with ultra-low power ideas and I was able to simulate
    a 30Hz relaxation oscillator running at 45nA/1V. I am waiting for the delivery of high-value resistors, but the same oscillator with resistors scaled down 10x works on the bench and consumes ~380nA/3V/360Hz which is still pretty awesome.

    This real device has been made of BSS123/BSS84 operating in the
    subthreshold realm -- the highest AC p-p voltage I can observe is
    ~500mV. There is a lot of interesting papers on subthreshold mode, so it
    is all good.

    But, out of curiosity, I replaced the FETs with BC847C/BC857C and it
    appears to work (in LTSpice!) even better, with V_BE sort of 350mV.
    I admit, no prototype so far. I didn't expect this -- could you please
    you recommend me some good book/papers on BJTs operated at nA levels?
    I would like to learn the theory in a proper way, as inferring it from a SPICE behavioural model might not be the best way to go. For example, it looks like the beta is extremely high there, even exponential. Does this
    BJT mode have a googlable name?

        Best regards, Piotr

    Lots of small BJTs work fine in the low nanoamps. I've used BFT25As as transdiodes down to 5 nA or so. They crapped out about 1 nA.

    The transconductance is a lot better than FETs down there!

    Cheers

    Phil Hobbs

    --
    Dr Philip C D Hobbs
    Principal Consultant
    ElectroOptical Innovations LLC / Hobbs ElectroOptics
    Optics, Electro-optics, Photonics, Analog Electronics
    Briarcliff Manor NY 10510

    http://electrooptical.net
    http://hobbs-eo.com

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  • From Phil Hobbs@21:1/5 to John Larkin on Wed May 11 17:14:08 2022
    John Larkin wrote:
    On Wed, 11 May 2022 21:23:17 +0200, Piotr Wyderski
    <bombald@protonmail.com> wrote:

    John Larkin wrote:

    There is a niche of building oscillators that run at very low supply
    voltages, ballpark 10 mV. I think jfets do pretty good.

    Yes, there are several interesting examples. The lowest voltage I know
    of is 20mV. But in this off-time research application related to the
    recent CeraCharge purchase I am trying to minimize current consumption,
    not voltage. It can stop oscillating at 1.2V, no problem with that. But
    if the current could be as low as 20nA, that would be something.

    Best regards, Piotr

    The AOE X-chapter book has some data on using BJTs at pA levels.
    Section 2x.9

    2N4401 holds up pretty well at Ic of 100 pA. I'd expect some very
    small RF transistors to be pretty good.




    The f_T goes in the tank--at 1 nA, even a BFT25A is a < 1-MHz transistor.

    Cheers

    Phil Hobbs

    --
    Dr Philip C D Hobbs
    Principal Consultant
    ElectroOptical Innovations LLC / Hobbs ElectroOptics
    Optics, Electro-optics, Photonics, Analog Electronics
    Briarcliff Manor NY 10510

    http://electrooptical.net
    http://hobbs-eo.com

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  • From Piotr Wyderski@21:1/5 to Phil Hobbs on Wed May 11 23:38:24 2022
    Phil Hobbs wrote:

    Lots of small BJTs work fine in the low nanoamps.  I've used BFT25As as transdiodes down to 5 nA or so.  They crapped out about 1 nA.

    This is getting really interesting. I didn't know that BJTs have useful subthreshold region too.

    The transconductance is a lot better than FETs down there!

    Indeed, Spice appears to say the same. I need to build a JFET probe in
    order not to disturb the single electron microcosmos down there with a
    dingy default 1Meg probe. And grab some radial resistors in the range of 47Meg+, as I don't fancy the idea of connecting hordes of 4.7Meg ones to
    get there.

    Best regards, Piotr

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  • From John Larkin@21:1/5 to pcdhSpamMeSenseless@electrooptical. on Wed May 11 15:21:04 2022
    On Wed, 11 May 2022 17:14:08 -0400, Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net> wrote:

    John Larkin wrote:
    On Wed, 11 May 2022 21:23:17 +0200, Piotr Wyderski
    <bombald@protonmail.com> wrote:

    John Larkin wrote:

    There is a niche of building oscillators that run at very low supply
    voltages, ballpark 10 mV. I think jfets do pretty good.

    Yes, there are several interesting examples. The lowest voltage I know
    of is 20mV. But in this off-time research application related to the
    recent CeraCharge purchase I am trying to minimize current consumption,
    not voltage. It can stop oscillating at 1.2V, no problem with that. But
    if the current could be as low as 20nA, that would be something.

    Best regards, Piotr

    The AOE X-chapter book has some data on using BJTs at pA levels.
    Section 2x.9

    2N4401 holds up pretty well at Ic of 100 pA. I'd expect some very
    small RF transistors to be pretty good.




    The f_T goes in the tank--at 1 nA, even a BFT25A is a < 1-MHz transistor.

    Cheers

    Phil Hobbs

    Well, 1 pA into 1 pF gets you 1 volt per second. Speed takes power.

    Big savings on heat sinks!




    --

    If a man will begin with certainties, he shall end with doubts,
    but if he will be content to begin with doubts he shall end in certainties. Francis Bacon

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  • From John Larkin@21:1/5 to bombald@protonmail.com on Wed May 11 15:30:02 2022
    On Wed, 11 May 2022 23:38:24 +0200, Piotr Wyderski
    <bombald@protonmail.com> wrote:

    Phil Hobbs wrote:

    Lots of small BJTs work fine in the low nanoamps. I've used BFT25As as
    transdiodes down to 5 nA or so. They crapped out about 1 nA.

    This is getting really interesting. I didn't know that BJTs have useful >subthreshold region too.

    I was theorizing that an LED, at low current, wouldn't have enough
    voltage across it to make visible photons. A typical green LED runs
    about 80 mV per decade current.

    I tried some green LEDs at 1 nA and they made visible light.

    I conjecture (ie guess) that base current makes collector current down
    at the single-electron level. 1 pA is just 6 milion electrons per
    second.

    --

    If a man will begin with certainties, he shall end with doubts,
    but if he will be content to begin with doubts he shall end in certainties. Francis Bacon

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  • From John Larkin@21:1/5 to bombald@protonmail.com on Wed May 11 15:31:17 2022
    On Wed, 11 May 2022 23:38:24 +0200, Piotr Wyderski
    <bombald@protonmail.com> wrote:

    Phil Hobbs wrote:

    Lots of small BJTs work fine in the low nanoamps. I've used BFT25As as
    transdiodes down to 5 nA or so. They crapped out about 1 nA.

    This is getting really interesting. I didn't know that BJTs have useful >subthreshold region too.

    The transconductance is a lot better than FETs down there!

    Indeed, Spice appears to say the same. I need to build a JFET probe in
    order not to disturb the single electron microcosmos down there with a
    dingy default 1Meg probe. And grab some radial resistors in the range of >47Meg+, as I don't fancy the idea of connecting hordes of 4.7Meg ones to
    get there.

    I have some 1T ohm 0805 resistors. High values are available.

    --

    If a man will begin with certainties, he shall end with doubts,
    but if he will be content to begin with doubts he shall end in certainties. Francis Bacon

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  • From bitrex@21:1/5 to John Larkin on Wed May 11 22:41:31 2022
    On 5/11/2022 6:21 PM, John Larkin wrote:
    On Wed, 11 May 2022 17:14:08 -0400, Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net> wrote:

    John Larkin wrote:
    On Wed, 11 May 2022 21:23:17 +0200, Piotr Wyderski
    <bombald@protonmail.com> wrote:

    John Larkin wrote:

    There is a niche of building oscillators that run at very low supply >>>>> voltages, ballpark 10 mV. I think jfets do pretty good.

    Yes, there are several interesting examples. The lowest voltage I know >>>> of is 20mV. But in this off-time research application related to the
    recent CeraCharge purchase I am trying to minimize current consumption, >>>> not voltage. It can stop oscillating at 1.2V, no problem with that. But >>>> if the current could be as low as 20nA, that would be something.

    Best regards, Piotr

    The AOE X-chapter book has some data on using BJTs at pA levels.
    Section 2x.9

    2N4401 holds up pretty well at Ic of 100 pA. I'd expect some very
    small RF transistors to be pretty good.




    The f_T goes in the tank--at 1 nA, even a BFT25A is a < 1-MHz transistor.

    Cheers

    Phil Hobbs

    Well, 1 pA into 1 pF gets you 1 volt per second. Speed takes power.

    Big savings on heat sinks!


    I remember seeing a sci-fi illustration when I was a kid of an alien
    species discovering the Voyager golden record many millions of years in
    the future - their little scout-ships the size of what would be 1:1000
    scale toys of a Space Shuttle touching down on its surface to investigate.

    Those guys really got it good with respect to the energy requirements of "manned" space travel.

    I also recall an alternative interpretation of general relativity (shape dynamics) says that time isn't relative and instead the sizes of objects
    in the Universe are what's relative.

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  • From Piotr Wyderski@21:1/5 to John Larkin on Thu May 12 07:47:39 2022
    John Larkin wrote:

    I have some 1T ohm 0805 resistors. High values are available.

    I have 1G in 1206. I have quite a lot of 10M-33M in 0603 too, but they
    make prototyping difficult. Wires help, hence this purchase of their THT equivalents. Should arrive today, so no problem here.

    Best regards, Piotr

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  • From Arie de Muijnck@21:1/5 to John Larkin on Thu May 12 09:17:30 2022
    On 2022-05-12 00:30, John Larkin wrote:

    I conjecture (ie guess) that base current makes collector current down
    at the single-electron level. 1 pA is just 6 milion electrons per
    second.

    AFAIK, it's not the base current but base voltage that controls the collector current. The base current is just an unfortunate side effect. The relation between them happens to be rather constant, hence the idea that hfe is the main factor. Ideally, the
    base 'leakage' could be so low that base current electrons can be counted. In that case, would the much higher collector current come in packets?

    Arie

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  • From Martin Brown@21:1/5 to John Larkin on Thu May 12 09:46:21 2022
    On 11/05/2022 23:30, John Larkin wrote:
    On Wed, 11 May 2022 23:38:24 +0200, Piotr Wyderski
    <bombald@protonmail.com> wrote:

    Phil Hobbs wrote:

    Lots of small BJTs work fine in the low nanoamps.  I've used BFT25As as >>> transdiodes down to 5 nA or so.  They crapped out about 1 nA.

    This is getting really interesting. I didn't know that BJTs have useful
    subthreshold region too.

    I was theorizing that an LED, at low current, wouldn't have enough
    voltage across it to make visible photons. A typical green LED runs
    about 80 mV per decade current.

    I tried some green LEDs at 1 nA and they made visible light.

    Certainly it a dark room you will see the die light up. I'd be surprised
    if it did it with less voltage across the junction than energy of the
    the photons being emitted (give or take a bit of slop for thermal phonon interactions boosting the odd one).

    These days at 5uA current drive you can see the white LED dies lit up
    glowing a faint blue white under normal lab conditions.

    I conjecture (ie guess) that base current makes collector current down
    at the single-electron level. 1 pA is just 6 milion electrons per
    second.

    I suspect that there was a good reason why we used 10^11 ohm precision resistors on Faraday amplifiers in mass specs but I never thought to
    ask. They would sometimes put a 10^10 or 10^9 resistor on one channel
    that was expected to have a higher beam current for some applications.

    "Resistors" in that very high value regime don't behave at all ideally
    either (maybe this has improved - I don't know). Considerable effort
    went into correcting their non-ideal behaviour in post processing.

    When the guy making them retired the first few batches with just his
    apprentice at the helm unsupervised were unusable. There was an art to
    cooking them just right to have the best combination of properties.

    It isn't just the active components that behave oddly at ultra low
    currents so does the pcb and the passive components. High value
    resistors tend to behave like a distributed capacitance at >10^10.

    --
    Regards,
    Martin Brown

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  • From jlarkin@highlandsniptechnology.com@21:1/5 to bombald@protonmail.com on Thu May 12 06:51:07 2022
    On Thu, 12 May 2022 07:47:39 +0200, Piotr Wyderski
    <bombald@protonmail.com> wrote:

    John Larkin wrote:

    I have some 1T ohm 0805 resistors. High values are available.

    I have 1G in 1206. I have quite a lot of 10M-33M in 0603 too, but they
    make prototyping difficult. Wires help, hence this purchase of their THT >equivalents. Should arrive today, so no problem here.

    Best regards, Piotr


    I did one photodiode amp that was all surface-mount but I couldn't
    find suitable high-value thinfilm resistors, so I had to fly-over a
    series pair of axial thinfilms.

    The high value surfmounts are all thickfilm, at least the ones I could
    get easily.

    I don't like very low current design. Measurements take ages to
    settle. Picosecond stuff happens right now.

    Ditto thermal measurements. Tedious.



    --

    Anybody can count to one.

    - Robert Widlar

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  • From Phil Hobbs@21:1/5 to Arie de Muijnck on Thu May 12 10:43:14 2022
    Arie de Muijnck wrote:
    On 2022-05-12 00:30, John Larkin wrote:

    I conjecture (ie guess) that base current makes collector current down
    at the single-electron level. 1 pA is just 6 milion electrons per
    second.

    AFAIK, it's not the base current but base voltage that controls the
    collector current. The base current is just an unfortunate side effect.
    The relation between them happens to be rather constant, hence the idea
    that hfe is the main factor. Ideally, the base 'leakage' could be so low
    that base current electrons can be counted. In that case, would the much higher collector current come in packets?

    Arie

    Yup, a BJT is a transconductance device with a loss mechanism
    (recombination in the base region) that produces leakage current. IIRC
    Mikko Kiviranta or somebody said that the beta of a BFP650 goes up to
    above 10000 at low temperature.

    Cheers

    Phil Hobbs

    --
    Dr Philip C D Hobbs
    Principal Consultant
    ElectroOptical Innovations LLC / Hobbs ElectroOptics
    Optics, Electro-optics, Photonics, Analog Electronics
    Briarcliff Manor NY 10510

    http://electrooptical.net
    http://hobbs-eo.com

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  • From Jan Panteltje@21:1/5 to jlarkin@highland_atwork_technology. on Thu May 12 14:23:14 2022
    On a sunny day (Wed, 11 May 2022 12:17:51 -0700) it happened John Larkin <jlarkin@highland_atwork_technology.com> wrote in <0n2o7h9e69qdlfnd2j843un2b2ffldj3t4@4ax.com>:

    On Wed, 11 May 2022 20:39:08 +0200, Piotr Wyderski
    <bombald@protonmail.com> wrote:

    Hi,

    I am experimenting with ultra-low power ideas and I was able to simulate
    a 30Hz relaxation oscillator running at 45nA/1V. I am waiting for the >>delivery of high-value resistors, but the same oscillator with resistors >>scaled down 10x works on the bench and consumes ~380nA/3V/360Hz which is >>still pretty awesome.

    This real device has been made of BSS123/BSS84 operating in the >>subthreshold realm -- the highest AC p-p voltage I can observe is
    ~500mV. There is a lot of interesting papers on subthreshold mode, so it
    is all good.

    But, out of curiosity, I replaced the FETs with BC847C/BC857C and it >>appears to work (in LTSpice!) even better, with V_BE sort of 350mV.
    I admit, no prototype so far. I didn't expect this -- could you please
    you recommend me some good book/papers on BJTs operated at nA levels?
    I would like to learn the theory in a proper way, as inferring it from a >>SPICE behavioural model might not be the best way to go. For example, it >>looks like the beta is extremely high there, even exponential. Does this >>BJT mode have a googlable name?

    Best regards, Piotr



    There is a niche of building oscillators that run at very low supply >voltages, ballpark 10 mV. I think jfets do pretty good.

    Have a JFET LC running from a thermocouple:
    http://panteltje.com/pub/40_mV_oscillator_IMG_3597.GIF
    http://panteltje.com/pub/40_mV_oscillator_waveform_on_gate_2Vpp_IMG_3598.GIF

    Circuit diagram:
    http://panteltje.com/pub/lighting_a_LED_with_a_candle_IMG_3604.GIF
    But did not design for very low current.


    Some PIC microprocessors take very little current
    The 18LF1XK22 uses 34 nA in sleep mode, and 650 nA @32 kHz clock (says dataheet)
    and can do a lot more than just oscillate...

    A depletion PHEMT might be good too.

    Temperature range would be interesting.

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  • From Don@21:1/5 to Arie de Muijnck on Thu May 12 15:35:43 2022
    Arie de Muijnck wrote:
    John Larkin wrote:

    I conjecture (ie guess) that base current makes collector current down
    at the single-electron level. 1 pA is just 6 milion electrons per
    second.

    AFAIK, it's not the base current but base voltage that controls the
    collector current. The base current is just an unfortunate side effect.
    The relation between them happens to be rather constant, hence the idea
    that hfe is the main factor. Ideally, the base 'leakage' could be so low
    that base current electrons can be counted. In that case, would the much higher collector current come in packets?

    Good point. You must be within the active region to use the hybrid model
    to ignore transconductance.

    Danke,

    --
    Don, KB7RPU, https://www.qsl.net/kb7rpu
    There was a young lady named Bright Whose speed was far faster than light;
    She set out one day In a relative way And returned on the previous night.

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  • From Phil Hobbs@21:1/5 to Don on Thu May 12 12:41:17 2022
    Don wrote:
    Arie de Muijnck wrote:
    John Larkin wrote:

    I conjecture (ie guess) that base current makes collector current down
    at the single-electron level. 1 pA is just 6 milion electrons per
    second.

    AFAIK, it's not the base current but base voltage that controls the
    collector current. The base current is just an unfortunate side effect.
    The relation between them happens to be rather constant, hence the idea
    that hfe is the main factor. Ideally, the base 'leakage' could be so low
    that base current electrons can be counted. In that case, would the much
    higher collector current come in packets?

    Good point. You must be within the active region to use the hybrid model
    to ignore transconductance.

    Danke,


    Don't ever ignore transconductance.

    Cheers

    Phil Hobbs

    --
    Dr Philip C D Hobbs
    Principal Consultant
    ElectroOptical Innovations LLC / Hobbs ElectroOptics
    Optics, Electro-optics, Photonics, Analog Electronics
    Briarcliff Manor NY 10510

    http://electrooptical.net
    http://hobbs-eo.com

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From John Larkin@21:1/5 to pcdhSpamMeSenseless@electrooptical. on Thu May 12 10:12:52 2022
    On Thu, 12 May 2022 10:43:14 -0400, Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net> wrote:

    Arie de Muijnck wrote:
    On 2022-05-12 00:30, John Larkin wrote:

    I conjecture (ie guess) that base current makes collector current down
    at the single-electron level. 1 pA is just 6 milion electrons per
    second.

    AFAIK, it's not the base current but base voltage that controls the
    collector current. The base current is just an unfortunate side effect.
    The relation between them happens to be rather constant, hence the idea
    that hfe is the main factor. Ideally, the base 'leakage' could be so low
    that base current electrons can be counted. In that case, would the much
    higher collector current come in packets?

    Arie

    Yup, a BJT is a transconductance device with a loss mechanism
    (recombination in the base region) that produces leakage current. IIRC
    Mikko Kiviranta or somebody said that the beta of a BFP650 goes up to
    above 10000 at low temperature.

    Cheers

    Phil Hobbs

    A transistor has c-b leakage, Is of the c-b diode, so turns itself on
    with the base open. Spice at least suggests that any amount of added
    base current increases collector current.

    That said, I don't understand this:

    Version 4
    SHEET 1 880 680
    WIRE 288 80 272 80
    WIRE 304 80 288 80
    WIRE 416 80 384 80
    WIRE 272 128 272 80
    WIRE 416 144 416 80
    WIRE 176 176 144 176
    WIRE 208 176 176 176
    WIRE 144 208 144 176
    WIRE 272 288 272 224
    WIRE 416 288 416 224
    WIRE 144 320 144 288
    FLAG 272 288 0
    FLAG 416 288 0
    FLAG 144 320 0
    FLAG 176 176 B
    FLAG 288 80 C
    SYMBOL npn 208 128 R0
    WINDOW 0 83 28 Left 2
    WINDOW 3 56 54 Left 2
    SYMATTR InstName Q1
    SYMATTR Value 2N5550
    SYMBOL voltage 416 128 R0
    WINDOW 0 49 37 Left 2
    WINDOW 3 54 64 Left 2
    SYMATTR InstName V1
    SYMATTR Value 5
    SYMBOL current 144 288 R180
    WINDOW 0 54 35 Left 2
    WINDOW 3 24 0 Left 2
    WINDOW 123 0 0 Left 0
    WINDOW 39 0 0 Left 0
    SYMATTR InstName I1
    SYMATTR Value SINE(0 100f 1)
    SYMBOL res 400 64 R90
    WINDOW 0 -8 51 VBottom 2
    WINDOW 3 32 56 VTop 2
    SYMATTR InstName R1
    SYMATTR Value 1
    TEXT 56 144 Left 2 !.tran 2
    TEXT 528 184 Left 2 !.op abstol 1e-18
    TEXT 528 216 Left 2 !.op gmin 1e-18
    TEXT 0 56 Left 2 ;Low current NPN test
    TEXT 32 88 Left 2 ;JL May 12 2022


    --

    If a man will begin with certainties, he shall end with doubts,
    but if he will be content to begin with doubts he shall end in certainties. Francis Bacon

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Don@21:1/5 to Phil Hobbs on Thu May 12 17:53:53 2022
    Phil Hobbs wrote:
    Don wrote:
    Arie de Muijnck wrote:
    John Larkin wrote:

    I conjecture (ie guess) that base current makes collector current down >>>> at the single-electron level. 1 pA is just 6 milion electrons per
    second.

    AFAIK, it's not the base current but base voltage that controls the
    collector current. The base current is just an unfortunate side effect.
    The relation between them happens to be rather constant, hence the idea
    that hfe is the main factor. Ideally, the base 'leakage' could be so low >>> that base current electrons can be counted. In that case, would the much >>> higher collector current come in packets?

    Good point. You must be within the active region to use the hybrid model
    to ignore transconductance.

    Don't ever ignore transconductance.

    "Hybrid" (as used by me above) is arguably ambiguous. "Hybrid
    equivalent" puts a finer point on it. And it indeed ignores
    transconductance:

    https://upload.wikimedia.org/wikipedia/commons/9/9f/BJT_h-parameters_(generalised).svg

    Danke,

    --
    Don, KB7RPU, https://www.qsl.net/kb7rpu
    There was a young lady named Bright Whose speed was far faster than light;
    She set out one day In a relative way And returned on the previous night.

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Phil Hobbs@21:1/5 to John Larkin on Thu May 12 15:01:06 2022
    John Larkin wrote:
    On Thu, 12 May 2022 10:43:14 -0400, Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net> wrote:

    Arie de Muijnck wrote:
    On 2022-05-12 00:30, John Larkin wrote:

    I conjecture (ie guess) that base current makes collector current down >>>> at the single-electron level. 1 pA is just 6 milion electrons per
    second.

    AFAIK, it's not the base current but base voltage that controls the
    collector current. The base current is just an unfortunate side effect.
    The relation between them happens to be rather constant, hence the idea
    that hfe is the main factor. Ideally, the base 'leakage' could be so low >>> that base current electrons can be counted. In that case, would the much >>> higher collector current come in packets?

    Arie

    Yup, a BJT is a transconductance device with a loss mechanism
    (recombination in the base region) that produces leakage current. IIRC
    Mikko Kiviranta or somebody said that the beta of a BFP650 goes up to
    above 10000 at low temperature.

    Cheers

    Phil Hobbs

    A transistor has c-b leakage, Is of the c-b diode, so turns itself on
    with the base open. Spice at least suggests that any amount of added
    base current increases collector current.

    That said, I don't understand this:
    <snip>

    I went into the control panel and set chgtol and absolute current
    tolerance to 1E-18, and it works fine.

    Hopefully JT is smiling indulgently somewhere. ;)

    Cheers

    Phil Hobbs

    --
    Dr Philip C D Hobbs
    Principal Consultant
    ElectroOptical Innovations LLC / Hobbs ElectroOptics
    Optics, Electro-optics, Photonics, Analog Electronics
    Briarcliff Manor NY 10510

    http://electrooptical.net
    http://hobbs-eo.com

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Phil Hobbs@21:1/5 to Don on Thu May 12 14:31:00 2022
    Don wrote:
    Phil Hobbs wrote:
    Don wrote:
    Arie de Muijnck wrote:
    John Larkin wrote:

    I conjecture (ie guess) that base current makes collector current down >>>>> at the single-electron level. 1 pA is just 6 milion electrons per
    second.

    AFAIK, it's not the base current but base voltage that controls the
    collector current. The base current is just an unfortunate side effect. >>>> The relation between them happens to be rather constant, hence the idea >>>> that hfe is the main factor. Ideally, the base 'leakage' could be so low >>>> that base current electrons can be counted. In that case, would the much >>>> higher collector current come in packets?

    Good point. You must be within the active region to use the hybrid model >>> to ignore transconductance.

    Don't ever ignore transconductance.

    "Hybrid" (as used by me above) is arguably ambiguous. "Hybrid
    equivalent" puts a finer point on it. And it indeed ignores
    transconductance:

    https://upload.wikimedia.org/wikipedia/commons/9/9f/BJT_h-parameters_(generalised).svg

    Danke,


    Of course it does. That's why nobody ever uses it for anything real
    AFAICT. The only reference I ever make to the h model is the current
    gain, because it's easy to keep the distinction between small-signal
    (h_FE) and large-signal (H_FE) straight.

    One could use upper- and lowercase beta, but uppercase beta is indistinguishable from B.

    You can turn LEDs on and off ignoring g_M, or make a rule-of-thumb
    single-ended CE amplifier with emitter degeneration. For anything differential, you use g_M for the design and beta for the sanity check.

    Beta is a useful number, mostly because it warns you about things you
    can't do, but even in beta-graded parts it varies by a factor of 2,
    whereas the transconductance of any two BJTs at the same collector
    current and same temperature, of whatever size, of whatever make,
    matches to a tiny fraction of 1%, at least at collector currents where
    beta is vaguely reasonable.

    Cheers

    Phil Hobbs

    --
    Dr Philip C D Hobbs
    Principal Consultant
    ElectroOptical Innovations LLC / Hobbs ElectroOptics
    Optics, Electro-optics, Photonics, Analog Electronics
    Briarcliff Manor NY 10510

    http://electrooptical.net
    http://hobbs-eo.com

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From whit3rd@21:1/5 to John Larkin on Thu May 12 13:34:27 2022
    On Thursday, May 12, 2022 at 1:20:11 PM UTC-7, John Larkin wrote:

    John Larkin wrote:

    A transistor has c-b leakage, Is of the c-b diode, so turns itself on
    with the base open. Spice at least suggests that any amount of added
    base current increases collector current.

    What I don't understand is why the sine wave current source doesn't
    make a sine wave of current.

    The base sees leakage plus a sinewave. How could that sum be
    proportional to a sinewave, when your applied signal is a sine,
    but leakage is a non-negligible constant?

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Phil Hobbs@21:1/5 to John Larkin on Thu May 12 16:41:47 2022
    John Larkin wrote:
    On Thu, 12 May 2022 15:01:06 -0400, Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net> wrote:

    John Larkin wrote:
    On Thu, 12 May 2022 10:43:14 -0400, Phil Hobbs
    <pcdhSpamMeSenseless@electrooptical.net> wrote:

    Arie de Muijnck wrote:
    On 2022-05-12 00:30, John Larkin wrote:

    I conjecture (ie guess) that base current makes collector current down >>>>>> at the single-electron level. 1 pA is just 6 milion electrons per
    second.

    AFAIK, it's not the base current but base voltage that controls the
    collector current. The base current is just an unfortunate side effect. >>>>> The relation between them happens to be rather constant, hence the idea >>>>> that hfe is the main factor. Ideally, the base 'leakage' could be so low >>>>> that base current electrons can be counted. In that case, would the much >>>>> higher collector current come in packets?

    Arie

    Yup, a BJT is a transconductance device with a loss mechanism
    (recombination in the base region) that produces leakage current. IIRC >>>> Mikko Kiviranta or somebody said that the beta of a BFP650 goes up to
    above 10000 at low temperature.

    Cheers

    Phil Hobbs

    A transistor has c-b leakage, Is of the c-b diode, so turns itself on
    with the base open. Spice at least suggests that any amount of added
    base current increases collector current.

    That said, I don't understand this:
    <snip>

    I went into the control panel and set chgtol and absolute current
    tolerance to 1E-18, and it works fine.

    Hopefully JT is smiling indulgently somewhere. ;)

    Cheers

    Phil Hobbs

    What I don't understand is why the sine wave current source doesn't
    make a sine wave of current.


    Right, but if you hack at the control panel as above, it does.

    See <https://electrooptical.net/www/sed/JLpuzzle.png>.

    Cheers

    Phil Hobbs

    --
    Dr Philip C D Hobbs
    Principal Consultant
    ElectroOptical Innovations LLC / Hobbs ElectroOptics
    Optics, Electro-optics, Photonics, Analog Electronics
    Briarcliff Manor NY 10510

    http://electrooptical.net
    http://hobbs-eo.com

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From whit3rd@21:1/5 to John Larkin on Thu May 12 13:18:15 2022
    On Wednesday, May 11, 2022 at 3:30:14 PM UTC-7, John Larkin wrote:

    I conjecture (ie guess) that base current makes collector current down
    at the single-electron level. 1 pA is just 6 milion electrons per
    second.

    The other numbers are important. A single-electron level is noise (recombination noise) in a semiconductor of any useful size.
    Transistor base and emitter contacts for most packages are dozens of
    microns, so discrete transistor volumes are on the order of 5E-5 cubic centimeters. At 1.4 x 10E10 charge carriers per cc, for silicon, there's mobile electrons and holes by the thousands in a transistor-size
    piece of nonconducting (undoped) silicon. A doped transistor has... more.

    It takes sizeable base charge to get above the noise.

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From John Larkin@21:1/5 to pcdhSpamMeSenseless@electrooptical. on Thu May 12 13:19:59 2022
    On Thu, 12 May 2022 15:01:06 -0400, Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net> wrote:

    John Larkin wrote:
    On Thu, 12 May 2022 10:43:14 -0400, Phil Hobbs
    <pcdhSpamMeSenseless@electrooptical.net> wrote:

    Arie de Muijnck wrote:
    On 2022-05-12 00:30, John Larkin wrote:

    I conjecture (ie guess) that base current makes collector current down >>>>> at the single-electron level. 1 pA is just 6 milion electrons per
    second.

    AFAIK, it's not the base current but base voltage that controls the
    collector current. The base current is just an unfortunate side effect. >>>> The relation between them happens to be rather constant, hence the idea >>>> that hfe is the main factor. Ideally, the base 'leakage' could be so low >>>> that base current electrons can be counted. In that case, would the much >>>> higher collector current come in packets?

    Arie

    Yup, a BJT is a transconductance device with a loss mechanism
    (recombination in the base region) that produces leakage current. IIRC
    Mikko Kiviranta or somebody said that the beta of a BFP650 goes up to
    above 10000 at low temperature.

    Cheers

    Phil Hobbs

    A transistor has c-b leakage, Is of the c-b diode, so turns itself on
    with the base open. Spice at least suggests that any amount of added
    base current increases collector current.

    That said, I don't understand this:
    <snip>

    I went into the control panel and set chgtol and absolute current
    tolerance to 1E-18, and it works fine.

    Hopefully JT is smiling indulgently somewhere. ;)

    Cheers

    Phil Hobbs

    What I don't understand is why the sine wave current source doesn't
    make a sine wave of current.

    --

    If a man will begin with certainties, he shall end with doubts,
    but if he will be content to begin with doubts he shall end in certainties. Francis Bacon

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From jlarkin@highlandsniptechnology.com@21:1/5 to All on Thu May 12 18:00:59 2022
    On Thu, 12 May 2022 13:34:27 -0700 (PDT), whit3rd <whit3rd@gmail.com>
    wrote:

    On Thursday, May 12, 2022 at 1:20:11 PM UTC-7, John Larkin wrote:

    John Larkin wrote:

    A transistor has c-b leakage, Is of the c-b diode, so turns itself on
    with the base open. Spice at least suggests that any amount of added
    base current increases collector current.

    What I don't understand is why the sine wave current source doesn't
    make a sine wave of current.

    The base sees leakage plus a sinewave. How could that sum be
    proportional to a sinewave, when your applied signal is a sine,
    but leakage is a non-negligible constant?

    A current source shouldn't care about its load. It should make its
    programmed current.



    --

    Anybody can count to one.

    - Robert Widlar

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Phil Hobbs@21:1/5 to jlarkin@highlandsniptechnology.com on Fri May 13 10:38:14 2022
    jlarkin@highlandsniptechnology.com wrote:
    On Thu, 12 May 2022 16:41:47 -0400, Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net> wrote:

    John Larkin wrote:
    On Thu, 12 May 2022 15:01:06 -0400, Phil Hobbs
    <pcdhSpamMeSenseless@electrooptical.net> wrote:

    John Larkin wrote:
    On Thu, 12 May 2022 10:43:14 -0400, Phil Hobbs
    <pcdhSpamMeSenseless@electrooptical.net> wrote:

    Arie de Muijnck wrote:
    On 2022-05-12 00:30, John Larkin wrote:

    I conjecture (ie guess) that base current makes collector current down >>>>>>>> at the single-electron level. 1 pA is just 6 milion electrons per >>>>>>>> second.

    AFAIK, it's not the base current but base voltage that controls the >>>>>>> collector current. The base current is just an unfortunate side effect. >>>>>>> The relation between them happens to be rather constant, hence the idea >>>>>>> that hfe is the main factor. Ideally, the base 'leakage' could be so low
    that base current electrons can be counted. In that case, would the much
    higher collector current come in packets?

    Arie

    Yup, a BJT is a transconductance device with a loss mechanism
    (recombination in the base region) that produces leakage current. IIRC >>>>>> Mikko Kiviranta or somebody said that the beta of a BFP650 goes up to >>>>>> above 10000 at low temperature.

    Cheers

    Phil Hobbs

    A transistor has c-b leakage, Is of the c-b diode, so turns itself on >>>>> with the base open. Spice at least suggests that any amount of added >>>>> base current increases collector current.

    That said, I don't understand this:
    <snip>

    I went into the control panel and set chgtol and absolute current
    tolerance to 1E-18, and it works fine.

    Hopefully JT is smiling indulgently somewhere. ;)


    What I don't understand is why the sine wave current source doesn't
    make a sine wave of current.


    Right, but if you hack at the control panel as above, it does.

    See <https://electrooptical.net/www/sed/JLpuzzle.png>.


    I can get the current source to make a sine wave if I skip the initial operating point solution, uic, with your spice settings, but the
    collector current is goofy, a 250 Hz triangle.

    One issue is maybe the roughly negative 1 gigavolt swing on the base.

    Nice and well-behaved for me, just tightening up all the tolerances
    (including some on the compression page of the control panel, which
    isn't shown on the screen shots).

    <https://electrooptical.net/www/sed/JLpuzzle2.png>

    Cheers

    Phil Hobbs

    --
    Dr Philip C D Hobbs
    Principal Consultant
    ElectroOptical Innovations LLC / Hobbs ElectroOptics
    Optics, Electro-optics, Photonics, Analog Electronics
    Briarcliff Manor NY 10510

    http://electrooptical.net
    http://hobbs-eo.com

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From jlarkin@highlandsniptechnology.com@21:1/5 to pcdhSpamMeSenseless@electrooptical. on Fri May 13 07:26:32 2022
    On Thu, 12 May 2022 16:41:47 -0400, Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net> wrote:

    John Larkin wrote:
    On Thu, 12 May 2022 15:01:06 -0400, Phil Hobbs
    <pcdhSpamMeSenseless@electrooptical.net> wrote:

    John Larkin wrote:
    On Thu, 12 May 2022 10:43:14 -0400, Phil Hobbs
    <pcdhSpamMeSenseless@electrooptical.net> wrote:

    Arie de Muijnck wrote:
    On 2022-05-12 00:30, John Larkin wrote:

    I conjecture (ie guess) that base current makes collector current down >>>>>>> at the single-electron level. 1 pA is just 6 milion electrons per >>>>>>> second.

    AFAIK, it's not the base current but base voltage that controls the >>>>>> collector current. The base current is just an unfortunate side effect. >>>>>> The relation between them happens to be rather constant, hence the idea >>>>>> that hfe is the main factor. Ideally, the base 'leakage' could be so low >>>>>> that base current electrons can be counted. In that case, would the much >>>>>> higher collector current come in packets?

    Arie

    Yup, a BJT is a transconductance device with a loss mechanism
    (recombination in the base region) that produces leakage current. IIRC >>>>> Mikko Kiviranta or somebody said that the beta of a BFP650 goes up to >>>>> above 10000 at low temperature.

    Cheers

    Phil Hobbs

    A transistor has c-b leakage, Is of the c-b diode, so turns itself on
    with the base open. Spice at least suggests that any amount of added
    base current increases collector current.

    That said, I don't understand this:
    <snip>

    I went into the control panel and set chgtol and absolute current
    tolerance to 1E-18, and it works fine.

    Hopefully JT is smiling indulgently somewhere. ;)

    Cheers

    Phil Hobbs

    What I don't understand is why the sine wave current source doesn't
    make a sine wave of current.


    Right, but if you hack at the control panel as above, it does.

    See <https://electrooptical.net/www/sed/JLpuzzle.png>.

    Cheers

    Phil Hobbs

    I can get the current source to make a sine wave if I skip the initial operating point solution, uic, with your spice settings, but the
    collector current is goofy, a 250 Hz triangle.

    One issue is maybe the roughly negative 1 gigavolt swing on the base.



    --

    Anybody can count to one.

    - Robert Widlar

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From John S@21:1/5 to John Larkin on Fri May 13 21:45:10 2022
    On 5/12/2022 3:19 PM, John Larkin wrote:
    On Thu, 12 May 2022 15:01:06 -0400, Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net> wrote:

    John Larkin wrote:
    On Thu, 12 May 2022 10:43:14 -0400, Phil Hobbs
    <pcdhSpamMeSenseless@electrooptical.net> wrote:

    Arie de Muijnck wrote:
    On 2022-05-12 00:30, John Larkin wrote:

    I conjecture (ie guess) that base current makes collector current down >>>>>> at the single-electron level. 1 pA is just 6 milion electrons per
    second.

    AFAIK, it's not the base current but base voltage that controls the
    collector current. The base current is just an unfortunate side effect. >>>>> The relation between them happens to be rather constant, hence the idea >>>>> that hfe is the main factor. Ideally, the base 'leakage' could be so low >>>>> that base current electrons can be counted. In that case, would the much >>>>> higher collector current come in packets?

    Arie

    Yup, a BJT is a transconductance device with a loss mechanism
    (recombination in the base region) that produces leakage current. IIRC >>>> Mikko Kiviranta or somebody said that the beta of a BFP650 goes up to
    above 10000 at low temperature.

    Cheers

    Phil Hobbs

    A transistor has c-b leakage, Is of the c-b diode, so turns itself on
    with the base open. Spice at least suggests that any amount of added
    base current increases collector current.

    That said, I don't understand this:
    <snip>

    I went into the control panel and set chgtol and absolute current
    tolerance to 1E-18, and it works fine.

    Hopefully JT is smiling indulgently somewhere. ;)

    Cheers

    Phil Hobbs

    What I don't understand is why the sine wave current source doesn't
    make a sine wave of current.



    Works great!

    Version 4
    SHEET 1 880 680
    WIRE -96 64 -176 64
    WIRE 288 80 272 80
    WIRE 304 80 288 80
    WIRE 416 80 384 80
    WIRE -176 128 -176 64
    WIRE -96 128 -96 64
    WIRE 272 128 272 80
    WIRE 416 144 416 80
    WIRE 176 176 144 176
    WIRE 208 176 176 176
    WIRE 144 208 144 176
    WIRE -176 224 -176 208
    WIRE -96 224 -96 208
    WIRE 272 288 272 224
    WIRE 416 288 416 224
    WIRE 144 320 144 288
    FLAG 272 288 0
    FLAG 416 288 0
    FLAG 144 320 0
    FLAG 176 176 B
    FLAG 288 80 C
    FLAG -176 224 0
    FLAG -96 224 0
    SYMBOL npn 208 128 R0
    WINDOW 0 83 28 Left 2
    WINDOW 3 56 54 Left 2
    SYMATTR InstName Q1
    SYMATTR Value 2N5550
    SYMBOL voltage 416 128 R0
    WINDOW 0 49 37 Left 2
    WINDOW 3 54 64 Left 2
    SYMATTR InstName V1
    SYMATTR Value 5
    SYMBOL current 144 288 R180
    WINDOW 0 54 35 Left 2
    WINDOW 3 24 0 Left 2
    WINDOW 123 0 0 Left 2
    WINDOW 39 0 0 Left 2
    SYMATTR InstName I1
    SYMATTR Value SINE(0 100f 1)
    SYMBOL res 400 64 R90
    WINDOW 0 -8 51 VBottom 2
    WINDOW 3 32 56 VTop 2
    SYMATTR InstName R1
    SYMATTR Value 1
    SYMBOL current -176 208 R180
    WINDOW 0 54 35 Left 2
    WINDOW 3 24 0 Left 2
    WINDOW 123 0 0 Left 2
    WINDOW 39 0 0 Left 2
    SYMATTR InstName I2
    SYMATTR Value SINE(0 100f 1)
    SYMBOL res -112 112 R0
    SYMATTR InstName R2
    SYMATTR Value 1g
    TEXT 56 144 Left 2 !.tran 2
    TEXT 528 184 Left 2 !.op abstol 1e-18
    TEXT 528 216 Left 2 !.op gmin 1e-18
    TEXT 0 56 Left 2 ;Low current NPN test
    TEXT 32 88 Left 2 ;JL May 12 2022

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Hul Tytus@21:1/5 to Piotr Wyderski on Sat May 14 06:04:39 2022
    Piotr you might look at the hc cmos series. They will operate in
    the 1 volt range with the expected lower current. One maker spoke
    of characterizing their devices at one something volts.
    I experimented with those supply voltages for devices
    working in the 100k cps area and all seemed pheasable.

    Hul


    Piotr Wyderski <bombald@protonmail.com> wrote:
    John Larkin wrote:

    There is a niche of building oscillators that run at very low supply voltages, ballpark 10 mV. I think jfets do pretty good.

    Yes, there are several interesting examples. The lowest voltage I know
    of is 20mV. But in this off-time research application related to the
    recent CeraCharge purchase I am trying to minimize current consumption,
    not voltage. It can stop oscillating at 1.2V, no problem with that. But
    if the current could be as low as 20nA, that would be something.

    Best regards, Piotr

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From jlarkin@highlandsniptechnology.com@21:1/5 to All on Sat May 14 07:22:37 2022
    On Fri, 13 May 2022 21:45:10 -0500, John S <Sophi.2@invalid.org>
    wrote:

    On 5/12/2022 3:19 PM, John Larkin wrote:
    On Thu, 12 May 2022 15:01:06 -0400, Phil Hobbs
    <pcdhSpamMeSenseless@electrooptical.net> wrote:

    John Larkin wrote:
    On Thu, 12 May 2022 10:43:14 -0400, Phil Hobbs
    <pcdhSpamMeSenseless@electrooptical.net> wrote:

    Arie de Muijnck wrote:
    On 2022-05-12 00:30, John Larkin wrote:

    I conjecture (ie guess) that base current makes collector current down >>>>>>> at the single-electron level. 1 pA is just 6 milion electrons per >>>>>>> second.

    AFAIK, it's not the base current but base voltage that controls the >>>>>> collector current. The base current is just an unfortunate side effect. >>>>>> The relation between them happens to be rather constant, hence the idea >>>>>> that hfe is the main factor. Ideally, the base 'leakage' could be so low >>>>>> that base current electrons can be counted. In that case, would the much >>>>>> higher collector current come in packets?

    Arie

    Yup, a BJT is a transconductance device with a loss mechanism
    (recombination in the base region) that produces leakage current. IIRC >>>>> Mikko Kiviranta or somebody said that the beta of a BFP650 goes up to >>>>> above 10000 at low temperature.

    Cheers

    Phil Hobbs

    A transistor has c-b leakage, Is of the c-b diode, so turns itself on
    with the base open. Spice at least suggests that any amount of added
    base current increases collector current.

    That said, I don't understand this:
    <snip>

    I went into the control panel and set chgtol and absolute current
    tolerance to 1E-18, and it works fine.

    Hopefully JT is smiling indulgently somewhere. ;)

    Cheers

    Phil Hobbs

    What I don't understand is why the sine wave current source doesn't
    make a sine wave of current.



    Works great!

    Not really. If yoy disconnect the base, the current source still
    swings +- 100 mv. That depends on some Spice settings.




    Version 4
    SHEET 1 880 680
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    TEXT 528 184 Left 2 !.op abstol 1e-18
    TEXT 528 216 Left 2 !.op gmin 1e-18
    TEXT 0 56 Left 2 ;Low current NPN test
    TEXT 32 88 Left 2 ;JL May 12 2022


    --

    Anybody can count to one.

    - Robert Widlar

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From piglet@21:1/5 to Hul Tytus on Sat May 14 19:03:40 2022
    On 14/05/2022 07:04, Hul Tytus wrote:
    Piotr you might look at the hc cmos series. They will operate in
    the 1 volt range with the expected lower current. One maker spoke
    of characterizing their devices at one something volts.
    I experimented with those supply voltages for devices
    working in the 100k cps area and all seemed pheasable.

    Hul


    Yes, I actually experienced HC cmos retaining stored latch states down
    into tens of millivolts region. However to make any kind of oscillator
    means passing slowly through a linear region and current consumption
    will shoot up. To make an oscillator a discrete design with high value
    series resistors might be better, this draws an average 10nA to make
    narrow pulses every 8-9 secs...

    Version 4
    SHEET 1 1160 680
    WIRE 32 -640 -208 -640
    WIRE 336 -640 32 -640
    WIRE 864 -640 336 -640
    WIRE 336 -592 336 -640
    WIRE 32 -544 32 -640
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    WIRE 336 -432 336 -512
    WIRE 576 -432 336 -432
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    WIRE 272 -320 32 -320
    WIRE 576 -304 576 -432
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    SYMATTR Value 1.3
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    SYMATTR InstName Q1
    SYMATTR Value 2N3906
    SYMBOL npn 272 -368 R0
    SYMATTR InstName Q2
    SYMATTR Value 2N3904
    SYMBOL res 320 -608 R0
    SYMATTR InstName R1
    SYMATTR Value 10Meg
    SYMBOL res 560 -96 R0
    SYMATTR InstName R3
    SYMATTR Value 100Meg
    SYMBOL res 16 -560 R0
    SYMATTR InstName R4
    SYMATTR Value 100Meg
    SYMBOL cap 16 -240 R0
    SYMATTR InstName C1
    SYMATTR Value 100n
    SYMBOL cap 560 -304 R0
    SYMATTR InstName C2
    SYMATTR Value 100n
    SYMBOL npn 800 32 R0
    SYMATTR InstName Q3
    SYMATTR Value 2N3904
    SYMBOL res 848 -480 R0
    SYMATTR InstName R5
    SYMATTR Value 10Meg
    SYMBOL res 320 160 R0
    SYMATTR InstName R6
    SYMATTR Value 10Meg
    SYMBOL res 528 64 R90
    WINDOW 0 0 56 VBottom 2
    WINDOW 3 32 56 VTop 2
    SYMATTR InstName R2
    SYMATTR Value 10Meg
    TEXT -242 360 Left 2 !.tran 100
    TEXT 928 336 Left 2 ;EPW SED MAY 2022
    TEXT 928 288 Left 2 ;Nano power pulser



    piglet

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Hul Tytus@21:1/5 to piglet on Sat May 14 20:47:04 2022
    Good point for an osicilator. The 10's of millivolts range you mention
    is an interesting area.

    Hul


    piglet <erichpwagner@hotmail.com> wrote:
    On 14/05/2022 07:04, Hul Tytus wrote:
    Piotr you might look at the hc cmos series. They will operate in
    the 1 volt range with the expected lower current. One maker spoke
    of characterizing their devices at one something volts.
    I experimented with those supply voltages for devices
    working in the 100k cps area and all seemed pheasable.

    Hul


    Yes, I actually experienced HC cmos retaining stored latch states down
    into tens of millivolts region. However to make any kind of oscillator
    means passing slowly through a linear region and current consumption
    will shoot up. To make an oscillator a discrete design with high value
    series resistors might be better, this draws an average 10nA to make
    narrow pulses every 8-9 secs...

    Version 4
    SHEET 1 1160 680
    WIRE 32 -640 -208 -640
    WIRE 336 -640 32 -640
    WIRE 864 -640 336 -640
    WIRE 336 -592 336 -640
    WIRE 32 -544 32 -640
    WIRE 864 -464 864 -640
    WIRE 336 -432 336 -512
    WIRE 576 -432 336 -432
    WIRE 336 -368 336 -432
    WIRE 32 -320 32 -464
    WIRE 272 -320 32 -320
    WIRE 576 -304 576 -432
    WIRE 32 -240 32 -320
    WIRE 336 -192 336 -272
    WIRE 576 -144 576 -240
    WIRE 576 -144 400 -144
    WIRE 576 -80 576 -144
    WIRE 32 -16 32 -176
    WIRE 336 -16 336 -96
    WIRE 336 -16 32 -16
    WIRE 864 32 864 -384
    WIRE -208 64 -208 -640
    WIRE 336 80 336 -16
    WIRE 432 80 336 80
    WIRE 800 80 512 80
    WIRE 336 176 336 80
    WIRE -208 288 -208 144
    WIRE 336 288 336 256
    WIRE 336 288 -208 288
    WIRE 576 288 576 0
    WIRE 576 288 336 288
    WIRE 864 288 864 128
    WIRE 864 288 576 288
    WIRE -208 320 -208 288
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    SYMBOL voltage -208 48 R0
    WINDOW 123 0 0 Left 0
    WINDOW 39 0 0 Left 0
    SYMATTR InstName V1
    SYMATTR Value 1.3
    SYMBOL pnp 400 -96 R180
    SYMATTR InstName Q1
    SYMATTR Value 2N3906
    SYMBOL npn 272 -368 R0
    SYMATTR InstName Q2
    SYMATTR Value 2N3904
    SYMBOL res 320 -608 R0
    SYMATTR InstName R1
    SYMATTR Value 10Meg
    SYMBOL res 560 -96 R0
    SYMATTR InstName R3
    SYMATTR Value 100Meg
    SYMBOL res 16 -560 R0
    SYMATTR InstName R4
    SYMATTR Value 100Meg
    SYMBOL cap 16 -240 R0
    SYMATTR InstName C1
    SYMATTR Value 100n
    SYMBOL cap 560 -304 R0
    SYMATTR InstName C2
    SYMATTR Value 100n
    SYMBOL npn 800 32 R0
    SYMATTR InstName Q3
    SYMATTR Value 2N3904
    SYMBOL res 848 -480 R0
    SYMATTR InstName R5
    SYMATTR Value 10Meg
    SYMBOL res 320 160 R0
    SYMATTR InstName R6
    SYMATTR Value 10Meg
    SYMBOL res 528 64 R90
    WINDOW 0 0 56 VBottom 2
    WINDOW 3 32 56 VTop 2
    SYMATTR InstName R2
    SYMATTR Value 10Meg
    TEXT -242 360 Left 2 !.tran 100
    TEXT 928 336 Left 2 ;EPW SED MAY 2022
    TEXT 928 288 Left 2 ;Nano power pulser



    piglet

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Piotr Wyderski@21:1/5 to piglet on Sat May 14 23:00:12 2022
    piglet wrote:

    Yes, I actually experienced HC cmos retaining stored latch states down
    into tens of millivolts region. However to make any kind of oscillator
    means passing slowly through a linear region and current consumption
    will shoot up. To make an oscillator a discrete design with high value
    series resistors might be better, this draws an average 10nA to make
    narrow pulses every 8-9 secs...

    Nice, your edges are super sharp. Here is mine, sort of 1us pulses at
    14Hz with 30nA average at 3V. The perhaps interesting part is the narrow
    pulse generator: the pulse duration is limited by the energy stored in
    C2, as the discharging cycle itself is orders of magnitude longer. With
    R7 I can specify any reasonable duration and it comes at no additional
    energy cost, as the energy to be dissipated has already come through R4.

    On the downside, I got stuck here: no idea how to transform the 100mV
    V_OUT pulses into the full VDD swing without a fancy 100mV Vth
    transistor and still keep the average power consumption low. The bias
    network for a differential amplifier or a common base stage will burn
    hundreds of times more power than the oscillator. Inductors don't seem
    to help here.

    Best regards, Piotr


    Version 4
    SHEET 1 880 680
    WIRE -176 -336 -256 -336
    WIRE -48 -336 -96 -336
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    WIRE 192 -336 80 -336
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    WIRE 576 -336 368 -336
    WIRE -48 -320 -48 -336
    WIRE 368 -272 368 -336
    WIRE -48 -240 -48 -256
    WIRE 192 -224 192 -336
    WIRE 576 -192 576 -336
    WIRE 368 -176 368 -192
    WIRE 528 -176 368 -176
    WIRE -256 -160 -256 -336
    WIRE 368 -160 368 -176
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    SYMATTR Value 3v
    SYMBOL res -16 -320 R270
    WINDOW 0 32 56 VTop 2
    WINDOW 3 0 56 VBottom 2
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    SYMATTR Value 1m
    SYMBOL cap -64 -320 R0
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    SYMATTR Value 100n
    SYMBOL res -192 -320 R270
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    WINDOW 3 0 56 VBottom 2
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    SYMATTR Value 47Meg
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    TEXT -280 16 Left 2 !.ic V(V_C2)=0
    TEXT -290 328 Left 2 !.tran 1

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From John S@21:1/5 to piglet on Sun May 15 10:56:16 2022
    On 5/14/2022 1:03 PM, piglet wrote:
    On 14/05/2022 07:04, Hul Tytus wrote:
    Piotr  you might look at the hc cmos series. They will operate in
    the 1 volt range with the expected lower current. One maker spoke
    of characterizing their devices at one something volts.
        I experimented with those supply voltages for devices
    working in the 100k cps area and all seemed pheasable.

    Hul


    Yes, I actually experienced HC cmos retaining stored latch states down
    into tens of millivolts region. However to make any kind of oscillator
    means passing slowly through a linear region and current consumption
    will shoot up. To make an oscillator a discrete design with high value
    series resistors might be better, this draws an average 10nA to make
    narrow pulses every 8-9 secs...

    Version 4
    [Snip SPICE listing]
    piglet

    Keep everything clean while building!

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Piotr Wyderski@21:1/5 to piglet on Sun May 22 20:32:20 2022
    piglet wrote:

    To make an oscillator a discrete design with high value
    series resistors might be better, this draws an average 10nA to make
    narrow pulses every 8-9 secs...

    After some prototyping I can confirm, your UJT-emulating circuit wins
    hands down. I removed R6, R2, Q3 and R5, changed C1 and C2 to 470p and
    coupled to the C2 discharge energy via a small transformer, getting
    beautiful 1us spikes @28Hz. Thank you, Piglet!

    Best regards, Piotr

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From John Larkin@21:1/5 to All on Mon May 23 10:19:18 2022
    On Sat, 14 May 2022 19:03:40 +0100, piglet <erichpwagner@hotmail.com>
    wrote:

    On 14/05/2022 07:04, Hul Tytus wrote:
    Piotr you might look at the hc cmos series. They will operate in
    the 1 volt range with the expected lower current. One maker spoke
    of characterizing their devices at one something volts.
    I experimented with those supply voltages for devices
    working in the 100k cps area and all seemed pheasable.

    Hul


    Yes, I actually experienced HC cmos retaining stored latch states down
    into tens of millivolts region. However to make any kind of oscillator
    means passing slowly through a linear region and current consumption
    will shoot up. To make an oscillator a discrete design with high value
    series resistors might be better, this draws an average 10nA to make
    narrow pulses every 8-9 secs...


    I want an LED blinker to show that a high-voltage power supply is
    still dangerous. It should discharge the supply at some low current
    and blink from, say, 1400 volts down to maybe 40.

    A variant of your circuit might work. Charge a cap through a string of depletion fets and modify your thing with a zener between emitters.

    --

    If a man will begin with certainties, he shall end with doubts,
    but if he will be content to begin with doubts he shall end in certainties. Francis Bacon

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From whit3rd@21:1/5 to John Larkin on Mon May 23 11:06:00 2022
    On Monday, May 23, 2022 at 10:19:30 AM UTC-7, John Larkin wrote:

    I want an LED blinker to show that a high-voltage power supply is
    still dangerous. It should discharge the supply at some low current
    and blink from, say, 1400 volts down to maybe 40.

    So, a series string of fifteen current-limit diodes running a capacitor- diac-LED blinkielight? S-272 seems suitable

    <https://www.mouser.com/datasheet/2/362/P22-23-CRD-1729293.pdf>

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From John Larkin@21:1/5 to All on Mon May 23 15:28:59 2022
    On Mon, 23 May 2022 11:06:00 -0700 (PDT), whit3rd <whit3rd@gmail.com>
    wrote:

    On Monday, May 23, 2022 at 10:19:30 AM UTC-7, John Larkin wrote:

    I want an LED blinker to show that a high-voltage power supply is
    still dangerous. It should discharge the supply at some low current
    and blink from, say, 1400 volts down to maybe 40.

    So, a series string of fifteen current-limit diodes running a capacitor- >diac-LED blinkielight? S-272 seems suitable

    <https://www.mouser.com/datasheet/2/362/P22-23-CRD-1729293.pdf>

    The Supertex LND150 is a 500 volt depletion fet. A source resistor
    will program the current, and they can apparently be strung in series
    without problems.

    Three of them would do. They are around 30 cents each.

    A spin on Piglet's circuit might to the blinker.

    --

    If a man will begin with certainties, he shall end with doubts,
    but if he will be content to begin with doubts he shall end in certainties. Francis Bacon

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Piotr Wyderski@21:1/5 to John Larkin on Tue May 24 06:40:33 2022
    John Larkin wrote:

    A spin on Piglet's circuit might to the blinker.

    It might, but Piglet's circuit excels at low power. This is not what you
    want to discharge a capacitor. Just power a 3V3-12V zener through your
    DMOS at the highest possible current limited by its thermal SOA and
    power any blinker from that zener. Plenty of free milliwatts to burn.

    Best regards, Piotr

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From whit3rd@21:1/5 to John Larkin on Tue May 24 01:08:17 2022
    On Monday, May 23, 2022 at 3:29:10 PM UTC-7, John Larkin wrote:
    On Mon, 23 May 2022 11:06:00 -0700 (PDT), whit3rd <whi...@gmail.com>
    wrote:
    On Monday, May 23, 2022 at 10:19:30 AM UTC-7, John Larkin wrote:

    I want an LED blinker to show that a high-voltage power supply is
    still dangerous. It should discharge the supply at some low current
    and blink from, say, 1400 volts down to maybe 40.

    So, a series string of fifteen current-limit diodes running a capacitor- >diac-LED blinkielight? S-272 seems suitable

    <https://www.mouser.com/datasheet/2/362/P22-23-CRD-1729293.pdf>
    The Supertex LND150 is a 500 volt depletion fet. A source resistor
    will program the current, and they can apparently be strung in series
    without problems.

    Yeah, and a 'current-limit diode' is also a depletion FET. With a zener
    limit specified (I'm not sure about LND150). Multiples only share
    the voltage with such a matching zener specification.

    A resistor would work, too, but the alarm blinkie would change frequency dramatically.

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From John Walliker@21:1/5 to All on Tue May 24 05:53:02 2022
    On Tuesday, 24 May 2022 at 09:08:21 UTC+1, whit3rd wrote:
    On Monday, May 23, 2022 at 3:29:10 PM UTC-7, John Larkin wrote:
    On Mon, 23 May 2022 11:06:00 -0700 (PDT), whit3rd <whi...@gmail.com>
    wrote:
    On Monday, May 23, 2022 at 10:19:30 AM UTC-7, John Larkin wrote:

    I want an LED blinker to show that a high-voltage power supply is
    still dangerous. It should discharge the supply at some low current
    and blink from, say, 1400 volts down to maybe 40.

    So, a series string of fifteen current-limit diodes running a capacitor- >diac-LED blinkielight? S-272 seems suitable

    <https://www.mouser.com/datasheet/2/362/P22-23-CRD-1729293.pdf>
    The Supertex LND150 is a 500 volt depletion fet. A source resistor
    will program the current, and they can apparently be strung in series without problems.
    Yeah, and a 'current-limit diode' is also a depletion FET. With a zener
    limit specified (I'm not sure about LND150). Multiples only share
    the voltage with such a matching zener specification.

    A resistor would work, too, but the alarm blinkie would change frequency dramatically.

    Does anyone actually sell surface mount LND150s at the moment? All
    the usual suppliers seem to be out of stock for at least several months.

    John

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From jlarkin@highlandsniptechnology.com@21:1/5 to jrwalliker@gmail.com on Tue May 24 07:05:19 2022
    On Tue, 24 May 2022 05:53:02 -0700 (PDT), John Walliker
    <jrwalliker@gmail.com> wrote:

    On Tuesday, 24 May 2022 at 09:08:21 UTC+1, whit3rd wrote:
    On Monday, May 23, 2022 at 3:29:10 PM UTC-7, John Larkin wrote:
    On Mon, 23 May 2022 11:06:00 -0700 (PDT), whit3rd <whi...@gmail.com>
    wrote:
    On Monday, May 23, 2022 at 10:19:30 AM UTC-7, John Larkin wrote:

    I want an LED blinker to show that a high-voltage power supply is
    still dangerous. It should discharge the supply at some low current
    and blink from, say, 1400 volts down to maybe 40.

    So, a series string of fifteen current-limit diodes running a capacitor- >> > >diac-LED blinkielight? S-272 seems suitable

    <https://www.mouser.com/datasheet/2/362/P22-23-CRD-1729293.pdf>
    The Supertex LND150 is a 500 volt depletion fet. A source resistor
    will program the current, and they can apparently be strung in series
    without problems.
    Yeah, and a 'current-limit diode' is also a depletion FET. With a zener
    limit specified (I'm not sure about LND150). Multiples only share
    the voltage with such a matching zener specification.

    A resistor would work, too, but the alarm blinkie would change frequency
    dramatically.

    Does anyone actually sell surface mount LND150s at the moment? All
    the usual suppliers seem to be out of stock for at least several months.

    John

    Mouser has LND250s, basically the same part.

    A current sink is a great way to discharge a power supply. No long
    exponential tail.

    In series with an LED, brigntness is constant until it hits bottom and
    winks out. My HV blinker would be similar, constant blink rate all the
    way down.



    --

    Anybody can count to one.

    - Robert Widlar

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Phil Hobbs@21:1/5 to John Larkin on Tue May 24 10:08:29 2022
    John Larkin wrote:
    On Mon, 23 May 2022 11:06:00 -0700 (PDT), whit3rd <whit3rd@gmail.com>
    wrote:

    On Monday, May 23, 2022 at 10:19:30 AM UTC-7, John Larkin wrote:

    I want an LED blinker to show that a high-voltage power supply is
    still dangerous. It should discharge the supply at some low current
    and blink from, say, 1400 volts down to maybe 40.

    So, a series string of fifteen current-limit diodes running a capacitor-
    diac-LED blinkielight? S-272 seems suitable

    <https://www.mouser.com/datasheet/2/362/P22-23-CRD-1729293.pdf>

    The Supertex LND150 is a 500 volt depletion fet. A source resistor
    will program the current, and they can apparently be strung in series
    without problems.

    Three of them would do. They are around 30 cents each.

    A spin on Piglet's circuit might to the blinker.


    I'd probably be happier with a gate bias string to force the voltages to equalize. Of course the resistors would have to be physically quite
    large to take the voltage.

    Cheers

    Phil Hobbs

    --
    Dr Philip C D Hobbs
    Principal Consultant
    ElectroOptical Innovations LLC / Hobbs ElectroOptics
    Optics, Electro-optics, Photonics, Analog Electronics
    Briarcliff Manor NY 10510

    http://electrooptical.net
    http://hobbs-eo.com

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From John Walliker@21:1/5 to jla...@highlandsniptechnology.com on Tue May 24 07:25:20 2022
    On Tuesday, 24 May 2022 at 15:05:31 UTC+1, jla...@highlandsniptechnology.com wrote:
    On Tue, 24 May 2022 05:53:02 -0700 (PDT), John Walliker

    Does anyone actually sell surface mount LND150s at the moment? All
    the usual suppliers seem to be out of stock for at least several months.

    John
    Mouser has LND250s, basically the same part.

    Thank you - John

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Phil Hobbs@21:1/5 to John Walliker on Tue May 24 10:43:08 2022
    John Walliker wrote:
    On Tuesday, 24 May 2022 at 09:08:21 UTC+1, whit3rd wrote:
    On Monday, May 23, 2022 at 3:29:10 PM UTC-7, John Larkin wrote:
    On Mon, 23 May 2022 11:06:00 -0700 (PDT), whit3rd <whi...@gmail.com>
    wrote:
    On Monday, May 23, 2022 at 10:19:30 AM UTC-7, John Larkin wrote:

    I want an LED blinker to show that a high-voltage power supply is
    still dangerous. It should discharge the supply at some low current
    and blink from, say, 1400 volts down to maybe 40.

    So, a series string of fifteen current-limit diodes running a capacitor- >>>> diac-LED blinkielight? S-272 seems suitable

    <https://www.mouser.com/datasheet/2/362/P22-23-CRD-1729293.pdf>
    The Supertex LND150 is a 500 volt depletion fet. A source resistor
    will program the current, and they can apparently be strung in series
    without problems.
    Yeah, and a 'current-limit diode' is also a depletion FET. With a zener
    limit specified (I'm not sure about LND150). Multiples only share
    the voltage with such a matching zener specification.

    A resistor would work, too, but the alarm blinkie would change frequency
    dramatically.

    Does anyone actually sell surface mount LND150s at the moment? All
    the usual suppliers seem to be out of stock for at least several months.

    John

    TO-92s are good for the soul.

    Cheers

    Phil Hobbs

    (Who just designed one into a supply-dictated board spin.) :(

    --
    Dr Philip C D Hobbs
    Principal Consultant
    ElectroOptical Innovations LLC / Hobbs ElectroOptics
    Optics, Electro-optics, Photonics, Analog Electronics
    Briarcliff Manor NY 10510

    http://electrooptical.net
    http://hobbs-eo.com

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From John Walliker@21:1/5 to Phil Hobbs on Tue May 24 09:07:34 2022
    On Tuesday, 24 May 2022 at 15:43:20 UTC+1, Phil Hobbs wrote:
    John Walliker wrote:

    Does anyone actually sell surface mount LND150s at the moment? All
    the usual suppliers seem to be out of stock for at least several months.

    John

    TO-92s are good for the soul.

    Maybe I should create a composite SOT-23/TO-92 footprint "just in case".
    John

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From jlarkin@highlandsniptechnology.com@21:1/5 to pcdhSpamMeSenseless@electrooptical. on Tue May 24 09:16:12 2022
    On Tue, 24 May 2022 10:43:08 -0400, Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net> wrote:

    John Walliker wrote:
    On Tuesday, 24 May 2022 at 09:08:21 UTC+1, whit3rd wrote:
    On Monday, May 23, 2022 at 3:29:10 PM UTC-7, John Larkin wrote:
    On Mon, 23 May 2022 11:06:00 -0700 (PDT), whit3rd <whi...@gmail.com>
    wrote:
    On Monday, May 23, 2022 at 10:19:30 AM UTC-7, John Larkin wrote:

    I want an LED blinker to show that a high-voltage power supply is
    still dangerous. It should discharge the supply at some low current >>>>>> and blink from, say, 1400 volts down to maybe 40.

    So, a series string of fifteen current-limit diodes running a capacitor- >>>>> diac-LED blinkielight? S-272 seems suitable

    <https://www.mouser.com/datasheet/2/362/P22-23-CRD-1729293.pdf>
    The Supertex LND150 is a 500 volt depletion fet. A source resistor
    will program the current, and they can apparently be strung in series
    without problems.
    Yeah, and a 'current-limit diode' is also a depletion FET. With a zener
    limit specified (I'm not sure about LND150). Multiples only share
    the voltage with such a matching zener specification.

    A resistor would work, too, but the alarm blinkie would change frequency >>> dramatically.

    Does anyone actually sell surface mount LND150s at the moment? All
    the usual suppliers seem to be out of stock for at least several months.

    John

    TO-92s are good for the soul.

    Rarely! But we're using a TO-92 LM35 to measure the temp of a CPU
    cooler that we're using as a mosfet heat sink. We'll glue it to the
    side of the cooler and plug it into three little pin sockets.


    Cheers

    Phil Hobbs

    (Who just designed one into a supply-dictated board spin.) :(

    Are TO-92s easier to get than surfmount parts? At least it's an
    option.



    --

    Anybody can count to one.

    - Robert Widlar

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From jlarkin@highlandsniptechnology.com@21:1/5 to pcdhSpamMeSenseless@electrooptical. on Tue May 24 09:18:45 2022
    On Tue, 24 May 2022 10:08:29 -0400, Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net> wrote:

    John Larkin wrote:
    On Mon, 23 May 2022 11:06:00 -0700 (PDT), whit3rd <whit3rd@gmail.com>
    wrote:

    On Monday, May 23, 2022 at 10:19:30 AM UTC-7, John Larkin wrote:

    I want an LED blinker to show that a high-voltage power supply is
    still dangerous. It should discharge the supply at some low current
    and blink from, say, 1400 volts down to maybe 40.

    So, a series string of fifteen current-limit diodes running a capacitor- >>> diac-LED blinkielight? S-272 seems suitable

    <https://www.mouser.com/datasheet/2/362/P22-23-CRD-1729293.pdf>

    The Supertex LND150 is a 500 volt depletion fet. A source resistor
    will program the current, and they can apparently be strung in series
    without problems.

    Three of them would do. They are around 30 cents each.

    A spin on Piglet's circuit might to the blinker.


    I'd probably be happier with a gate bias string to force the voltages to >equalize. Of course the resistors would have to be physically quite
    large to take the voltage.

    Cheers

    Phil Hobbs

    Somebody told me (was it you?) that they are OK in series. One or two
    may avalanche somewhere above 500 volts and one will actually regulate
    the current. I'm talking 50 or 100 uA in my case.



    --

    Anybody can count to one.

    - Robert Widlar

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From John Larkin@21:1/5 to jrwalliker@gmail.com on Tue May 24 09:50:27 2022
    On Tue, 24 May 2022 07:25:20 -0700 (PDT), John Walliker
    <jrwalliker@gmail.com> wrote:

    On Tuesday, 24 May 2022 at 15:05:31 UTC+1, jla...@highlandsniptechnology.com wrote:
    On Tue, 24 May 2022 05:53:02 -0700 (PDT), John Walliker

    Does anyone actually sell surface mount LND150s at the moment? All
    the usual suppliers seem to be out of stock for at least several months.

    John
    Mouser has LND250s, basically the same part.

    Thank you - John

    We have 2500 in stock. I could spare a few to anyone who wants to play
    with them.

    --

    If a man will begin with certainties, he shall end with doubts,
    but if he will be content to begin with doubts he shall end in certainties. Francis Bacon

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From John Larkin@21:1/5 to jrwalliker@gmail.com on Tue May 24 09:51:24 2022
    On Tue, 24 May 2022 09:07:34 -0700 (PDT), John Walliker
    <jrwalliker@gmail.com> wrote:

    On Tuesday, 24 May 2022 at 15:43:20 UTC+1, Phil Hobbs wrote:
    John Walliker wrote:

    Does anyone actually sell surface mount LND150s at the moment? All
    the usual suppliers seem to be out of stock for at least several months. >> >
    John

    TO-92s are good for the soul.

    Maybe I should create a composite SOT-23/TO-92 footprint "just in case".
    John

    Just put them in parallel on the schematic.

    --

    If a man will begin with certainties, he shall end with doubts,
    but if he will be content to begin with doubts he shall end in certainties. Francis Bacon

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Phil Hobbs@21:1/5 to jlarkin@highlandsniptechnology.com on Tue May 24 16:47:30 2022
    jlarkin@highlandsniptechnology.com wrote:
    On Tue, 24 May 2022 10:08:29 -0400, Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net> wrote:

    John Larkin wrote:
    On Mon, 23 May 2022 11:06:00 -0700 (PDT), whit3rd <whit3rd@gmail.com>
    wrote:

    On Monday, May 23, 2022 at 10:19:30 AM UTC-7, John Larkin wrote:

    I want an LED blinker to show that a high-voltage power supply is
    still dangerous. It should discharge the supply at some low current
    and blink from, say, 1400 volts down to maybe 40.

    So, a series string of fifteen current-limit diodes running a capacitor- >>>> diac-LED blinkielight? S-272 seems suitable

    <https://www.mouser.com/datasheet/2/362/P22-23-CRD-1729293.pdf>

    The Supertex LND150 is a 500 volt depletion fet. A source resistor
    will program the current, and they can apparently be strung in series
    without problems.

    Three of them would do. They are around 30 cents each.

    A spin on Piglet's circuit might to the blinker.


    I'd probably be happier with a gate bias string to force the voltages to
    equalize. Of course the resistors would have to be physically quite
    large to take the voltage.



    Somebody told me (was it you?) that they are OK in series. One or two
    may avalanche somewhere above 500 volts and one will actually regulate
    the current. I'm talking 50 or 100 uA in my case.



    I've never used them above about 250V.

    Cheers

    Phil Hobbs

    --
    Dr Philip C D Hobbs
    Principal Consultant
    ElectroOptical Innovations LLC / Hobbs ElectroOptics
    Optics, Electro-optics, Photonics, Analog Electronics
    Briarcliff Manor NY 10510

    http://electrooptical.net
    http://hobbs-eo.com

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Phil Hobbs@21:1/5 to jlarkin@highlandsniptechnology.com on Tue May 24 16:46:22 2022
    jlarkin@highlandsniptechnology.com wrote:
    On Tue, 24 May 2022 10:43:08 -0400, Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net> wrote:

    John Walliker wrote:
    On Tuesday, 24 May 2022 at 09:08:21 UTC+1, whit3rd wrote:
    On Monday, May 23, 2022 at 3:29:10 PM UTC-7, John Larkin wrote:
    On Mon, 23 May 2022 11:06:00 -0700 (PDT), whit3rd <whi...@gmail.com> >>>>> wrote:
    On Monday, May 23, 2022 at 10:19:30 AM UTC-7, John Larkin wrote:

    I want an LED blinker to show that a high-voltage power supply is >>>>>>> still dangerous. It should discharge the supply at some low current >>>>>>> and blink from, say, 1400 volts down to maybe 40.

    So, a series string of fifteen current-limit diodes running a capacitor- >>>>>> diac-LED blinkielight? S-272 seems suitable

    <https://www.mouser.com/datasheet/2/362/P22-23-CRD-1729293.pdf>
    The Supertex LND150 is a 500 volt depletion fet. A source resistor
    will program the current, and they can apparently be strung in series >>>>> without problems.
    Yeah, and a 'current-limit diode' is also a depletion FET. With a zener >>>> limit specified (I'm not sure about LND150). Multiples only share
    the voltage with such a matching zener specification.

    A resistor would work, too, but the alarm blinkie would change frequency >>>> dramatically.

    Does anyone actually sell surface mount LND150s at the moment? All
    the usual suppliers seem to be out of stock for at least several months. >>>
    John

    TO-92s are good for the soul.

    Rarely! But we're using a TO-92 LM35 to measure the temp of a CPU
    cooler that we're using as a mosfet heat sink. We'll glue it to the
    side of the cooler and plug it into three little pin sockets.


    Cheers

    Phil Hobbs

    (Who just designed one into a supply-dictated board spin.) :(

    Are TO-92s easier to get than surfmount parts? At least it's an
    option.

    Some of them.

    Cheers

    Phil Hobbs


    --
    Dr Philip C D Hobbs
    Principal Consultant
    ElectroOptical Innovations LLC / Hobbs ElectroOptics
    Optics, Electro-optics, Photonics, Analog Electronics
    Briarcliff Manor NY 10510

    http://electrooptical.net
    http://hobbs-eo.com

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From jlarkin@highlandsniptechnology.com@21:1/5 to pcdhSpamMeSenseless@electrooptical. on Tue May 24 15:58:53 2022
    On Tue, 24 May 2022 16:47:30 -0400, Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net> wrote:

    jlarkin@highlandsniptechnology.com wrote:
    On Tue, 24 May 2022 10:08:29 -0400, Phil Hobbs
    <pcdhSpamMeSenseless@electrooptical.net> wrote:

    John Larkin wrote:
    On Mon, 23 May 2022 11:06:00 -0700 (PDT), whit3rd <whit3rd@gmail.com>
    wrote:

    On Monday, May 23, 2022 at 10:19:30 AM UTC-7, John Larkin wrote:

    I want an LED blinker to show that a high-voltage power supply is
    still dangerous. It should discharge the supply at some low current >>>>>> and blink from, say, 1400 volts down to maybe 40.

    So, a series string of fifteen current-limit diodes running a capacitor- >>>>> diac-LED blinkielight? S-272 seems suitable

    <https://www.mouser.com/datasheet/2/362/P22-23-CRD-1729293.pdf>

    The Supertex LND150 is a 500 volt depletion fet. A source resistor
    will program the current, and they can apparently be strung in series
    without problems.

    Three of them would do. They are around 30 cents each.

    A spin on Piglet's circuit might to the blinker.


    I'd probably be happier with a gate bias string to force the voltages to >>> equalize. Of course the resistors would have to be physically quite
    large to take the voltage.



    Somebody told me (was it you?) that they are OK in series. One or two
    may avalanche somewhere above 500 volts and one will actually regulate
    the current. I'm talking 50 or 100 uA in my case.



    I've never used them above about 250V.

    Cheers

    Phil Hobbs

    I tested one. It avalanches at 620 volts, no damage at low current.

    The gate zeners at about +-40, again no damage.



    --

    Anybody can count to one.

    - Robert Widlar

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From piglet@21:1/5 to John Larkin on Wed May 25 11:21:22 2022
    On 23/05/2022 11:28 pm, John Larkin wrote:
    On Mon, 23 May 2022 11:06:00 -0700 (PDT), whit3rd <whit3rd@gmail.com>
    wrote:

    On Monday, May 23, 2022 at 10:19:30 AM UTC-7, John Larkin wrote:

    I want an LED blinker to show that a high-voltage power supply is
    still dangerous. It should discharge the supply at some low current
    and blink from, say, 1400 volts down to maybe 40.

    So, a series string of fifteen current-limit diodes running a capacitor-
    diac-LED blinkielight? S-272 seems suitable

    <https://www.mouser.com/datasheet/2/362/P22-23-CRD-1729293.pdf>

    The Supertex LND150 is a 500 volt depletion fet. A source resistor
    will program the current, and they can apparently be strung in series
    without problems.

    Three of them would do. They are around 30 cents each.

    A spin on Piglet's circuit might to the blinker.


    My preference would be to skip the depletion fets and just use dropper resistors - cheaper, more reliable, and best of all the non constant
    blink rate gives a good visual confirmation that the HV capacitor is
    actually discharging.

    Blinking could be as simple as a diac or bjt used as negistor. Spice
    won't model E-B breakdown and reverse beta so can't simulate negistor
    operation but breadboarding would be very quick.

    piglet

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From piglet@21:1/5 to Piotr Wyderski on Wed May 25 11:17:03 2022
    On 22/05/2022 7:32 pm, Piotr Wyderski wrote:
    piglet wrote:

    To make an oscillator a discrete design with high value series
    resistors might be better, this draws an average 10nA to make narrow
    pulses every 8-9 secs...

    After some prototyping I can confirm, your UJT-emulating circuit wins
    hands down. I removed R6, R2, Q3 and R5, changed C1 and C2 to 470p and coupled to the C2 discharge energy via a small transformer, getting
    beautiful 1us spikes @28Hz. Thank you, Piglet!

        Best regards, Piotr



    You are very welcome, always pleased when a dirt cheap descrete circuit
    still beats the world. It is not my design, the complementary series multivibrator has been around since the 1960s.

    piglet

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Piotr Wyderski@21:1/5 to piglet on Wed May 25 14:17:52 2022
    piglet wrote:

    You are very welcome, always pleased when a dirt cheap descrete circuit
    still beats the world. It is not my design, the complementary series multivibrator has been around since the 1960s.

    This is how it looks now. L1 and L3 pump the flyback core, L3 boosts the voltage of the core reset pulse to 600mV+, even at 1.2V_IN, R5 steals
    that pulse (or not), Q3 detects if there was the pulse, C3/Q4 is a
    zero-power monostable (assuming there are no pulses from Q3) and M1
    makes that information accessible to the external world. It is shocking
    how simple it is and how well it works.

    Best regards, Piotr

    Version 4
    SHEET 1 2136 1236
    WIRE 416 -176 176 -176
    WIRE 720 -176 416 -176
    WIRE 1264 -176 720 -176
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    SYMATTR Value 3
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    TEXT 560 -376 Left 2 !.param N_SEC={N_PRI*4}
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    TEXT 560 -320 Left 2 !.param L_PRI={N_PRI*N_PRI*AL}
    TEXT 560 -296 Left 2 !.param L_SEC={N_SEC*N_SEC*AL}
    TEXT 560 -272 Left 2 !.param L_SENSE={N_SENSE*N_SENSE*AL}
    TEXT 240 800 Left 2 !K L1 L2 L3 L4 0.995
    TEXT 144 1048 Left 2 !.tran 1
    TEXT 912 -376 Left 2 ;PRI/SEC: twisted 6x26 DNE0.2mm @ 10mm OD ring F938.
    TEXT 912 -352 Left 2 ;SENSE: TIW!!!
    TEXT 1376 1048 Left 2 !.ic V(V_OUT)=0
    TEXT 1008 1192 Left 2 !.model MYSW SW(Ron=1m Roff=1G Vt=.5 Vh=-.4)

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  • From Piotr Wyderski@21:1/5 to All on Wed May 25 14:41:27 2022
    Piotr Wyderski wrote:

    Just a supplement: the interesting part is IMO discharging the caps
    through the flyback chokes. It makes the pulses at no additional energy
    cost (beyond what has already been transferred through the 100M
    resistors), so they are both signal and power at the same time.
    Unfortunately, the amount of energy stored in that 470p capacitor
    charged to 1V is so tiny that the autotransformer is not able to boost
    the voltage (merely ~150mV at the low V_IN end) to open Q3. This is a
    constant energy regime: if you add more turns to L3, the voltage reaches
    some saturation point and the reset pulses are getting longer instead,
    as L and C both go up. This saturation point is ~400mV, too low for an
    NPN to notice (assuming zero power detection; you can't afford a proper
    PNP long tailed pair). A 400mV EPAD would cut the mustard, but another
    solution is to double the amount of energy deposited to the core. Hence
    the dual-pumping idea utilising L1 and L4. With that it works even down
    to 1.1V V_IN. Balancing these available picojoules is sort of obscene. :)

    Best regards, Piotr

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  • From Phil Hobbs@21:1/5 to jlarkin@highlandsniptechnology.com on Wed May 25 09:40:48 2022
    jlarkin@highlandsniptechnology.com wrote:
    On Tue, 24 May 2022 16:47:30 -0400, Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net> wrote:

    jlarkin@highlandsniptechnology.com wrote:
    On Tue, 24 May 2022 10:08:29 -0400, Phil Hobbs
    <pcdhSpamMeSenseless@electrooptical.net> wrote:

    John Larkin wrote:
    On Mon, 23 May 2022 11:06:00 -0700 (PDT), whit3rd <whit3rd@gmail.com> >>>>> wrote:

    On Monday, May 23, 2022 at 10:19:30 AM UTC-7, John Larkin wrote:

    I want an LED blinker to show that a high-voltage power supply is >>>>>>> still dangerous. It should discharge the supply at some low current >>>>>>> and blink from, say, 1400 volts down to maybe 40.

    So, a series string of fifteen current-limit diodes running a capacitor- >>>>>> diac-LED blinkielight? S-272 seems suitable

    <https://www.mouser.com/datasheet/2/362/P22-23-CRD-1729293.pdf>

    The Supertex LND150 is a 500 volt depletion fet. A source resistor
    will program the current, and they can apparently be strung in series >>>>> without problems.

    Three of them would do. They are around 30 cents each.

    A spin on Piglet's circuit might to the blinker.


    I'd probably be happier with a gate bias string to force the voltages to >>>> equalize. Of course the resistors would have to be physically quite
    large to take the voltage.



    Somebody told me (was it you?) that they are OK in series. One or two
    may avalanche somewhere above 500 volts and one will actually regulate
    the current. I'm talking 50 or 100 uA in my case.



    I've never used them above about 250V.

    I tested one. It avalanches at 620 volts, no damage at low current.

    The gate zeners at about +-40, again no damage.

    Yabbut, at 1400V at least one and probably two of them will be
    continuously avalanching during normal operation, unless the drain
    curves are squishy enough to take up the unit-to-unit spread in I_DSS.
    (Maybe they are.) That would take a lot of testing to confirm as safe.

    The avalanche voltage increases with temperature, so there'd be no
    automatic sharing of dissipation.

    Cheers

    Phil Hobbs

    --
    Dr Philip C D Hobbs
    Principal Consultant
    ElectroOptical Innovations LLC / Hobbs ElectroOptics
    Optics, Electro-optics, Photonics, Analog Electronics
    Briarcliff Manor NY 10510

    http://electrooptical.net
    http://hobbs-eo.com

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  • From jlarkin@highlandsniptechnology.com@21:1/5 to pcdhSpamMeSenseless@electrooptical. on Wed May 25 06:57:40 2022
    On Wed, 25 May 2022 09:40:48 -0400, Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net> wrote:

    jlarkin@highlandsniptechnology.com wrote:
    On Tue, 24 May 2022 16:47:30 -0400, Phil Hobbs
    <pcdhSpamMeSenseless@electrooptical.net> wrote:

    jlarkin@highlandsniptechnology.com wrote:
    On Tue, 24 May 2022 10:08:29 -0400, Phil Hobbs
    <pcdhSpamMeSenseless@electrooptical.net> wrote:

    John Larkin wrote:
    On Mon, 23 May 2022 11:06:00 -0700 (PDT), whit3rd <whit3rd@gmail.com> >>>>>> wrote:

    On Monday, May 23, 2022 at 10:19:30 AM UTC-7, John Larkin wrote: >>>>>>>
    I want an LED blinker to show that a high-voltage power supply is >>>>>>>> still dangerous. It should discharge the supply at some low current >>>>>>>> and blink from, say, 1400 volts down to maybe 40.

    So, a series string of fifteen current-limit diodes running a capacitor-
    diac-LED blinkielight? S-272 seems suitable

    <https://www.mouser.com/datasheet/2/362/P22-23-CRD-1729293.pdf>

    The Supertex LND150 is a 500 volt depletion fet. A source resistor >>>>>> will program the current, and they can apparently be strung in series >>>>>> without problems.

    Three of them would do. They are around 30 cents each.

    A spin on Piglet's circuit might to the blinker.


    I'd probably be happier with a gate bias string to force the voltages to >>>>> equalize. Of course the resistors would have to be physically quite >>>>> large to take the voltage.



    Somebody told me (was it you?) that they are OK in series. One or two
    may avalanche somewhere above 500 volts and one will actually regulate >>>> the current. I'm talking 50 or 100 uA in my case.



    I've never used them above about 250V.

    I tested one. It avalanches at 620 volts, no damage at low current.

    The gate zeners at about +-40, again no damage.

    Yabbut, at 1400V at least one and probably two of them will be
    continuously avalanching during normal operation, unless the drain
    curves are squishy enough to take up the unit-to-unit spread in I_DSS.
    (Maybe they are.) That would take a lot of testing to confirm as safe.

    The avalanche voltage increases with temperature, so there'd be no
    automatic sharing of dissipation.

    Cheers

    Phil Hobbs

    If two avalanche at about 650 volts each, that runs the third one as
    the current limiter, at roughly 100 volts. Seems like it just works.

    At 100 uA, the two that avalanche dissipate maybe 65 mW each. The
    linear one is necessarily less.

    Now I need a good blinker circuit.





    --

    Anybody can count to one.

    - Robert Widlar

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  • From jlarkin@highlandsniptechnology.com@21:1/5 to All on Wed May 25 07:01:15 2022
    On Wed, 25 May 2022 11:21:22 +0100, piglet <erichpwagner@hotmail.com>
    wrote:

    On 23/05/2022 11:28 pm, John Larkin wrote:
    On Mon, 23 May 2022 11:06:00 -0700 (PDT), whit3rd <whit3rd@gmail.com>
    wrote:

    On Monday, May 23, 2022 at 10:19:30 AM UTC-7, John Larkin wrote:

    I want an LED blinker to show that a high-voltage power supply is
    still dangerous. It should discharge the supply at some low current
    and blink from, say, 1400 volts down to maybe 40.

    So, a series string of fifteen current-limit diodes running a capacitor- >>> diac-LED blinkielight? S-272 seems suitable

    <https://www.mouser.com/datasheet/2/362/P22-23-CRD-1729293.pdf>

    The Supertex LND150 is a 500 volt depletion fet. A source resistor
    will program the current, and they can apparently be strung in series
    without problems.

    Three of them would do. They are around 30 cents each.

    A spin on Piglet's circuit might to the blinker.


    My preference would be to skip the depletion fets and just use dropper >resistors - cheaper, more reliable, and best of all the non constant
    blink rate gives a good visual confirmation that the HV capacitor is
    actually discharging.

    The discharge would be a slow exponential and the blink rate would
    approach zero towards the end. Neither sounds good to me.


    Blinking could be as simple as a diac or bjt used as negistor. Spice
    won't model E-B breakdown and reverse beta so can't simulate negistor >operation but breadboarding would be very quick.

    piglet


    --

    Anybody can count to one.

    - Robert Widlar

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  • From Phil Hobbs@21:1/5 to jlarkin@highlandsniptechnology.com on Wed May 25 10:32:49 2022
    jlarkin@highlandsniptechnology.com wrote:
    On Wed, 25 May 2022 09:40:48 -0400, Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net> wrote:

    jlarkin@highlandsniptechnology.com wrote:
    On Tue, 24 May 2022 16:47:30 -0400, Phil Hobbs
    <pcdhSpamMeSenseless@electrooptical.net> wrote:

    jlarkin@highlandsniptechnology.com wrote:
    On Tue, 24 May 2022 10:08:29 -0400, Phil Hobbs
    <pcdhSpamMeSenseless@electrooptical.net> wrote:

    John Larkin wrote:
    On Mon, 23 May 2022 11:06:00 -0700 (PDT), whit3rd <whit3rd@gmail.com> >>>>>>> wrote:

    On Monday, May 23, 2022 at 10:19:30 AM UTC-7, John Larkin wrote: >>>>>>>>
    I want an LED blinker to show that a high-voltage power supply is >>>>>>>>> still dangerous. It should discharge the supply at some low current >>>>>>>>> and blink from, say, 1400 volts down to maybe 40.

    So, a series string of fifteen current-limit diodes running a capacitor-
    diac-LED blinkielight? S-272 seems suitable

    <https://www.mouser.com/datasheet/2/362/P22-23-CRD-1729293.pdf> >>>>>>>
    The Supertex LND150 is a 500 volt depletion fet. A source resistor >>>>>>> will program the current, and they can apparently be strung in series >>>>>>> without problems.

    Three of them would do. They are around 30 cents each.

    A spin on Piglet's circuit might to the blinker.


    I'd probably be happier with a gate bias string to force the voltages to >>>>>> equalize. Of course the resistors would have to be physically quite >>>>>> large to take the voltage.



    Somebody told me (was it you?) that they are OK in series. One or two >>>>> may avalanche somewhere above 500 volts and one will actually regulate >>>>> the current. I'm talking 50 or 100 uA in my case.



    I've never used them above about 250V.

    I tested one. It avalanches at 620 volts, no damage at low current.

    The gate zeners at about +-40, again no damage.

    Yabbut, at 1400V at least one and probably two of them will be
    continuously avalanching during normal operation, unless the drain
    curves are squishy enough to take up the unit-to-unit spread in I_DSS.
    (Maybe they are.) That would take a lot of testing to confirm as safe.

    The avalanche voltage increases with temperature, so there'd be no
    automatic sharing of dissipation.


    If two avalanche at about 650 volts each, that runs the third one as
    the current limiter, at roughly 100 volts. Seems like it just works.

    At 100 uA, the two that avalanche dissipate maybe 65 mW each. The
    linear one is necessarily less.

    Provided that there's no long-term damage mechanism. It's going to be
    in that state for a long long time.

    Now I need a good blinker circuit.

    Cheers

    Phil Hobbs

    --
    Dr Philip C D Hobbs
    Principal Consultant
    ElectroOptical Innovations LLC / Hobbs ElectroOptics
    Optics, Electro-optics, Photonics, Analog Electronics
    Briarcliff Manor NY 10510

    http://electrooptical.net
    http://hobbs-eo.com

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  • From keith@kjwdesigns.com@21:1/5 to Phil Hobbs on Wed May 25 09:22:48 2022
    On Wednesday, 25 May 2022 at 06:41:00 UTC-7, Phil Hobbs wrote:
    ...
    Somebody told me (was it you?) that they are OK in series. One or two
    may avalanche somewhere above 500 volts and one will actually regulate >>> the current. I'm talking 50 or 100 uA in my case.



    I've never used them above about 250V.
    I tested one. It avalanches at 620 volts, no damage at low current.

    The gate zeners at about +-40, again no damage.
    Yabbut, at 1400V at least one and probably two of them will be
    continuously avalanching during normal operation, unless the drain
    curves are squishy enough to take up the unit-to-unit spread in I_DSS.
    (Maybe they are.) That would take a lot of testing to confirm as safe.

    The avalanche voltage increases with temperature, so there'd be no
    automatic sharing of dissipation.
    ...

    The Art of Electronics - The X Chapters. depicts that configuration and variants with a discussion in section 3.x.6.5

    The simple configuration with just source resistors can have steps in the current as the voltage is varied as each device in turn avalanches.

    kw

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  • From John Larkin@21:1/5 to keith@kjwdesigns.com on Wed May 25 11:22:30 2022
    On Wed, 25 May 2022 09:22:48 -0700 (PDT), "ke...@kjwdesigns.com" <keith@kjwdesigns.com> wrote:

    On Wednesday, 25 May 2022 at 06:41:00 UTC-7, Phil Hobbs wrote:
    ...
    Somebody told me (was it you?) that they are OK in series. One or two
    may avalanche somewhere above 500 volts and one will actually regulate >> >>> the current. I'm talking 50 or 100 uA in my case.



    I've never used them above about 250V.
    I tested one. It avalanches at 620 volts, no damage at low current.

    The gate zeners at about +-40, again no damage.
    Yabbut, at 1400V at least one and probably two of them will be
    continuously avalanching during normal operation, unless the drain
    curves are squishy enough to take up the unit-to-unit spread in I_DSS.
    (Maybe they are.) That would take a lot of testing to confirm as safe.

    The avalanche voltage increases with temperature, so there'd be no
    automatic sharing of dissipation.
    ...

    The Art of Electronics - The X Chapters. depicts that configuration and variants with a discussion in section 3.x.6.5

    The simple configuration with just source resistors can have steps in the current as the voltage is varied as each device in turn avalanches.

    kw

    The simple version, 3x57a with LND150s would be fine for a 1400 volt
    LED blinker. And there are some diacs that would work for the periodic
    cap discharge into the LED. 9 or so parts total.

    --

    If a man will begin with certainties, he shall end with doubts,
    but if he will be content to begin with doubts he shall end in certainties. Francis Bacon

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  • From Piotr Wyderski@21:1/5 to John Larkin on Wed May 25 20:31:12 2022
    John Larkin wrote:

    The simple version, 3x57a with LND150s would be fine for a 1400 volt
    LED blinker.

    Why wouldn't you just use a 1.7kV+ rated DMOS?

    Best regards, Piotr

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  • From jlarkin@highlandsniptechnology.com@21:1/5 to bombald@protonmail.com on Wed May 25 19:08:33 2022
    On Wed, 25 May 2022 20:31:12 +0200, Piotr Wyderski
    <bombald@protonmail.com> wrote:

    John Larkin wrote:

    The simple version, 3x57a with LND150s would be fine for a 1400 volt
    LED blinker.

    Why wouldn't you just use a 1.7kV+ rated DMOS?

    Best regards, Piotr

    Had a part in mind? If it's enhancement mode, it will need something
    to bias it up.

    We do have the LND150s in stock, SOT23 package.



    --

    Anybody can count to one.

    - Robert Widlar

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  • From Piotr Wyderski@21:1/5 to jlarkin@highlandsniptechnology.com on Thu May 26 07:51:28 2022
    jlarkin@highlandsniptechnology.com wrote:

    Had a part in mind? If it's enhancement mode, it will need something
    to bias it up.

    We do have the LND150s in stock, SOT23 package.

    Mouser has this IXTA1N170DHV. More expensive that LND150, but I am not
    sure if a safety circuit is the best place for savings and IIRC your
    business is of the high-added-value/low volume profile anyway. Just
    saying, it's your decision.

    I use the IXTA08N100D2HV for the same purpose (have a blinker too, and a
    buzzer specifically tuned to emulate a fighter jet warning system: https://youtu.be/fd50GtnXR7Y?t=1145, just couldn't resist), but my cap
    voltage is under 900V, 650V typical.

    Best regards, Piotr

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  • From jlarkin@highlandsniptechnology.com@21:1/5 to bombald@protonmail.com on Thu May 26 07:46:20 2022
    On Thu, 26 May 2022 07:51:28 +0200, Piotr Wyderski
    <bombald@protonmail.com> wrote:

    jlarkin@highlandsniptechnology.com wrote:

    Had a part in mind? If it's enhancement mode, it will need something
    to bias it up.

    We do have the LND150s in stock, SOT23 package.

    Mouser has this IXTA1N170DHV. More expensive that LND150, but I am not
    sure if a safety circuit is the best place for savings and IIRC your
    business is of the high-added-value/low volume profile anyway. Just
    saying, it's your decision.

    The 1400v supply is low current and doesn't store lethal energy, but
    someone could damage parts by poking around while there's still
    voltage. The linear discharge with blinker helps with that, and is
    cool too. Sometimes we do things just because they are cool.


    I use the IXTA08N100D2HV for the same purpose (have a blinker too, and a >buzzer specifically tuned to emulate a fighter jet warning system: >https://youtu.be/fd50GtnXR7Y?t=1145, just couldn't resist), but my cap >voltage is under 900V, 650V typical.

    Best regards, Piotr

    That is an interesting part, but Mouser has four for $20 each. That's
    another factor these days, availability and price.

    We also use DN2530, a 300 v depl fet in SOT89. It good for discharging
    bigger caps.

    In a couple of boxes with gigantic caps, we used a depletion fet + LED indicator and a discharge resistor + pushbutton inside, so our techs
    are warned and didn't have to wait minutes to poke around.



    --

    Anybody can count to one.

    - Robert Widlar

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  • From Piotr Wyderski@21:1/5 to jlarkin@highlandsniptechnology.com on Thu May 26 18:06:43 2022
    jlarkin@highlandsniptechnology.com wrote:

    The 1400v supply is low current and doesn't store lethal energy

    Oh, in that case never mind. My comment was entirely safety-driven.

    Sometimes we do things just because they are cool.

    So do I. :)

    We also use DN2530, a 300 v depl fet in SOT89. It good for discharging
    bigger caps.

    I use it as a resettable fuse. The short-circit current is limited and
    the part just stops being hot when the short-circuit is removed. The carbon-based PTCs wear off.

    Best regards, Piotr

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  • From jlarkin@highlandsniptechnology.com@21:1/5 to bombald@protonmail.com on Thu May 26 09:24:14 2022
    On Thu, 26 May 2022 18:06:43 +0200, Piotr Wyderski
    <bombald@protonmail.com> wrote:

    jlarkin@highlandsniptechnology.com wrote:

    The 1400v supply is low current and doesn't store lethal energy

    Oh, in that case never mind. My comment was entirely safety-driven.

    Sometimes we do things just because they are cool.

    So do I. :)

    We also use DN2530, a 300 v depl fet in SOT89. It good for discharging
    bigger caps.

    I use it as a resettable fuse. The short-circit current is limited and
    the part just stops being hot when the short-circuit is removed. The >carbon-based PTCs wear off.

    Best regards, Piotr


    Ixys makes a self-protecting SSR, CPC1540. Off leakage is picoamps.

    If you drive the input full-time, it becomes a fuse.



    --

    Anybody can count to one.

    - Robert Widlar

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