• Parasitic capacitance of SMD resistors and their generated noise

    From pavelmargulis@gmail.com@21:1/5 to All on Mon Mar 7 03:10:25 2022
    Hello, colleagues
    My question is about basic component that we all are working with - resistor, actually SMD 0402 type of them.
    There are few technologies on the market to make them - thick film, thin film, metal film, and probably some more.
    Resistors produced by different technologies has different performance. Currently I am interested in three characteristics for 0402 size of resistors - parasitic parallel capacitance, parasitic series inductance, and generated noise, and their repeatability/stability/predictability in production. I am talking about frequency
    range from DC and up to 2 GHz.
    Could you provide/reveal values of these properties of 0402 resistors made by each of above technologies? Any additional information will be appreciated.
    Thank you

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  • From Jeroen Belleman@21:1/5 to pavelm...@gmail.com on Mon Mar 7 12:50:45 2022
    On 2022-03-07 12:10, pavelm...@gmail.com wrote:
    Hello, colleagues

    My question is about basic component that we all
    are working with - resistor, actually SMD 0402 type of them. There
    are few technologies on the market to make them - thick film, thin
    film, metal film, and probably some more. Resistors produced by
    different technologies has different performance. Currently I am
    interested in three characteristics for 0402 size of resistors -
    parasitic parallel capacitance, parasitic series inductance, and
    generated noise, and their repeatability/stability/predictability in production. I am talking about frequency range from DC and up to 2
    GHz. Could you provide/reveal values of these properties of 0402
    resistors made by each of above technologies? Any additional
    information will be appreciated. Thank you



    I measured parasitic capacitance and inductance for 1206 resistors
    and got about 50fF and 500pH. I'd expect about the same for 0402,
    because they have the same shape. Of course, pad layout and trace
    width matters, as does the proximity of other conductors. I only
    measured 1% metal film resistors.

    Common wisdom says that only metal film should be used where noise
    matters. I never made comparative measurements. In my field,
    resistor cost is relatively negligible, so I tend to use metal
    film almost everywhere.

    Jeroen Belleman

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  • From jlarkin@highlandsniptechnology.com@21:1/5 to jeroen@nospam.please on Mon Mar 7 07:31:26 2022
    On Mon, 07 Mar 2022 12:50:45 +0100, Jeroen Belleman
    <jeroen@nospam.please> wrote:

    On 2022-03-07 12:10, pavelm...@gmail.com wrote:
    Hello, colleagues

    My question is about basic component that we all
    are working with - resistor, actually SMD 0402 type of them. There
    are few technologies on the market to make them - thick film, thin
    film, metal film, and probably some more. Resistors produced by
    different technologies has different performance. Currently I am
    interested in three characteristics for 0402 size of resistors -
    parasitic parallel capacitance, parasitic series inductance, and
    generated noise, and their repeatability/stability/predictability in
    production. I am talking about frequency range from DC and up to 2
    GHz. Could you provide/reveal values of these properties of 0402
    resistors made by each of above technologies? Any additional
    information will be appreciated. Thank you



    I measured parasitic capacitance and inductance for 1206 resistors
    and got about 50fF and 500pH. I'd expect about the same for 0402,
    because they have the same shape. Of course, pad layout and trace
    width matters, as does the proximity of other conductors. I only
    measured 1% metal film resistors.

    The parasitics of various resistors are easily googled.


    Common wisdom says that only metal film should be used where noise
    matters. I never made comparative measurements. In my field,
    resistor cost is relatively negligible, so I tend to use metal
    film almost everywhere.

    Jeroen Belleman

    Johnson noise must be the same regardless of the materials.

    Thick-film resistors can have excess noise if there is voltage across
    them, but it's hard to measure. I managed to measure some once, but it
    took very high value resistors and high voltages.

    High tempco resistors in a voltage divider or equivalent can make low
    frequency (subsonic) noise from small temperature fluctuations.



    --

    I yam what I yam - Popeye

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  • From Phil Hobbs@21:1/5 to Jeroen Belleman on Mon Mar 7 11:38:41 2022
    Jeroen Belleman wrote:
    On 2022-03-07 12:10, pavelm...@gmail.com wrote:
    Hello, colleagues

    My question is about basic component that we all
    are working with - resistor, actually SMD 0402 type of them. There
    are few technologies on the market to make them - thick film, thin
    film, metal film, and probably some more. Resistors produced by
    different technologies has different performance. Currently I am
    interested in three characteristics for 0402 size of resistors -
    parasitic parallel capacitance, parasitic series inductance, and
    generated noise, and their repeatability/stability/predictability in
    production. I am talking about frequency range from DC and up to 2
    GHz. Could you provide/reveal values of these properties of 0402
    resistors made by each of above technologies? Any additional
    information will be appreciated. Thank you



    I measured parasitic capacitance and inductance for 1206 resistors
    and got about 50fF and 500pH. I'd expect about the same for 0402,
    because they have the same shape. Of course, pad layout and trace
    width matters, as does the proximity of other conductors. I only
    measured 1% metal film resistors.

    Common wisdom says that only metal film should be used where noise
    matters. I never made comparative measurements. In my field,
    resistor cost is relatively negligible, so I tend to use metal
    film almost everywhere.

    Jeroen Belleman

    Yup. Cermet, thick film, and anything with carbon in it are disastrous
    for 1/f noise. They're all pretty well equivalent at high frequency.
    ("Thin film" is SMT-speak for "metal film".)

    JL made some TDR measurements of (iirc) thin film resistors and showed
    that the inductance was significantly reduced by mounting them upside
    down, so that the resistive track was next to the board.

    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 Rick C@21:1/5 to Phil Hobbs on Mon Mar 7 08:48:12 2022
    On Monday, March 7, 2022 at 11:38:54 AM UTC-5, Phil Hobbs wrote:
    Jeroen Belleman wrote:
    On 2022-03-07 12:10, pavelm...@gmail.com wrote:
    Hello, colleagues

    My question is about basic component that we all
    are working with - resistor, actually SMD 0402 type of them. There
    are few technologies on the market to make them - thick film, thin
    film, metal film, and probably some more. Resistors produced by
    different technologies has different performance. Currently I am
    interested in three characteristics for 0402 size of resistors -
    parasitic parallel capacitance, parasitic series inductance, and
    generated noise, and their repeatability/stability/predictability in
    production. I am talking about frequency range from DC and up to 2
    GHz. Could you provide/reveal values of these properties of 0402
    resistors made by each of above technologies? Any additional
    information will be appreciated. Thank you



    I measured parasitic capacitance and inductance for 1206 resistors
    and got about 50fF and 500pH. I'd expect about the same for 0402,
    because they have the same shape. Of course, pad layout and trace
    width matters, as does the proximity of other conductors. I only
    measured 1% metal film resistors.

    Common wisdom says that only metal film should be used where noise
    matters. I never made comparative measurements. In my field,
    resistor cost is relatively negligible, so I tend to use metal
    film almost everywhere.

    Jeroen Belleman
    Yup. Cermet, thick film, and anything with carbon in it are disastrous
    for 1/f noise. They're all pretty well equivalent at high frequency.
    ("Thin film" is SMT-speak for "metal film".)

    JL made some TDR measurements of (iirc) thin film resistors and showed
    that the inductance was significantly reduced by mounting them upside
    down, so that the resistive track was next to the board.

    The inductance or the impedance? If the resistive layer has a smaller spacing from the board it would also impact the capacitance to the ground layer greatly impacting the impedance, probably much more than just the inductance.

    --

    Rick C.

    - Get 1,000 miles of free Supercharging
    - Tesla referral code - https://ts.la/richard11209

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  • From Phil Hobbs@21:1/5 to jlarkin@highlandsniptechnology.com on Mon Mar 7 12:03:17 2022
    jlarkin@highlandsniptechnology.com wrote:
    On Mon, 07 Mar 2022 12:50:45 +0100, Jeroen Belleman
    <jeroen@nospam.please> wrote:

    On 2022-03-07 12:10, pavelm...@gmail.com wrote:
    Hello, colleagues

    My question is about basic component that we all
    are working with - resistor, actually SMD 0402 type of them. There
    are few technologies on the market to make them - thick film, thin
    film, metal film, and probably some more. Resistors produced by
    different technologies has different performance. Currently I am
    interested in three characteristics for 0402 size of resistors -
    parasitic parallel capacitance, parasitic series inductance, and
    generated noise, and their repeatability/stability/predictability in
    production. I am talking about frequency range from DC and up to 2
    GHz. Could you provide/reveal values of these properties of 0402
    resistors made by each of above technologies? Any additional
    information will be appreciated. Thank you



    I measured parasitic capacitance and inductance for 1206 resistors
    and got about 50fF and 500pH. I'd expect about the same for 0402,
    because they have the same shape. Of course, pad layout and trace
    width matters, as does the proximity of other conductors. I only
    measured 1% metal film resistors.

    The parasitics of various resistors are easily googled.


    Common wisdom says that only metal film should be used where noise
    matters. I never made comparative measurements. In my field,
    resistor cost is relatively negligible, so I tend to use metal
    film almost everywhere.

    Jeroen Belleman

    Johnson noise must be the same regardless of the materials.

    Thick-film resistors can have excess noise if there is voltage across
    them, but it's hard to measure. I managed to measure some once, but it
    took very high value resistors and high voltages.

    As Kipling's Shipwrecked Mariner said to the Whale, "Not so, but far otherwise." (At least in my business, i.e. ultrasensitive measurements,
    that is.)

    One time I was chasing my tail for about a day, trying to figure out why
    my shiny new super low noise laser driver gizmo was exhibiting horrific
    1/f noise on the spectrum analyzer. It turned out to be the classic
    Tektronix 50-ohm 2-W BNC feedthrough terminator I was using--it was made
    of cermet. Switching to metal film dropped the 1/f noise by about two
    orders of magnitude IIRC. Not subtle at all.



    High tempco resistors in a voltage divider or equivalent can make low frequency (subsonic) noise from small temperature fluctuations.

    Yup. Random temperature drift has roughly a 1/f**2 noise PSD.

    The LIGO folks published a study on noise in resistors, IIRC, but I'm
    not laying my hands on it at the moment.

    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 Mon Mar 7 09:21:55 2022
    On Mon, 7 Mar 2022 11:38:41 -0500, Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net> wrote:

    Jeroen Belleman wrote:
    On 2022-03-07 12:10, pavelm...@gmail.com wrote:
    Hello, colleagues

    My question is about basic component that we all
    are working with - resistor, actually SMD 0402 type of them. There
    are few technologies on the market to make them - thick film, thin
    film, metal film, and probably some more. Resistors produced by
    different technologies has different performance. Currently I am
    interested in three characteristics for 0402 size of resistors -
    parasitic parallel capacitance, parasitic series inductance, and
    generated noise, and their repeatability/stability/predictability in
    production. I am talking about frequency range from DC and up to 2
    GHz. Could you provide/reveal values of these properties of 0402
    resistors made by each of above technologies? Any additional
    information will be appreciated. Thank you



    I measured parasitic capacitance and inductance for 1206 resistors
    and got about 50fF and 500pH. I'd expect about the same for 0402,
    because they have the same shape. Of course, pad layout and trace
    width matters, as does the proximity of other conductors. I only
    measured 1% metal film resistors.

    Common wisdom says that only metal film should be used where noise
    matters. I never made comparative measurements. In my field,
    resistor cost is relatively negligible, so I tend to use metal
    film almost everywhere.

    Jeroen Belleman

    Yup. Cermet, thick film, and anything with carbon in it are disastrous
    for 1/f noise. They're all pretty well equivalent at high frequency.
    ("Thin film" is SMT-speak for "metal film".)

    JL made some TDR measurements of (iirc) thin film resistors and showed
    that the inductance was significantly reduced by mounting them upside
    down, so that the resistive track was next to the board.

    Cheers

    Phil Hobbs

    Regular cermets, but the geometric effects are the same.

    You can buy resistors without wrap-around end caps, intended to solder
    element down.



    --

    I yam what I yam - Popeye

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  • From jlarkin@highlandsniptechnology.com@21:1/5 to pcdhSpamMeSenseless@electrooptical. on Mon Mar 7 09:19:21 2022
    On Mon, 7 Mar 2022 12:03:17 -0500, Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net> wrote:

    jlarkin@highlandsniptechnology.com wrote:
    On Mon, 07 Mar 2022 12:50:45 +0100, Jeroen Belleman
    <jeroen@nospam.please> wrote:

    On 2022-03-07 12:10, pavelm...@gmail.com wrote:
    Hello, colleagues

    My question is about basic component that we all
    are working with - resistor, actually SMD 0402 type of them. There
    are few technologies on the market to make them - thick film, thin
    film, metal film, and probably some more. Resistors produced by
    different technologies has different performance. Currently I am
    interested in three characteristics for 0402 size of resistors -
    parasitic parallel capacitance, parasitic series inductance, and
    generated noise, and their repeatability/stability/predictability in
    production. I am talking about frequency range from DC and up to 2
    GHz. Could you provide/reveal values of these properties of 0402
    resistors made by each of above technologies? Any additional
    information will be appreciated. Thank you



    I measured parasitic capacitance and inductance for 1206 resistors
    and got about 50fF and 500pH. I'd expect about the same for 0402,
    because they have the same shape. Of course, pad layout and trace
    width matters, as does the proximity of other conductors. I only
    measured 1% metal film resistors.

    The parasitics of various resistors are easily googled.


    Common wisdom says that only metal film should be used where noise
    matters. I never made comparative measurements. In my field,
    resistor cost is relatively negligible, so I tend to use metal
    film almost everywhere.

    Jeroen Belleman

    Johnson noise must be the same regardless of the materials.

    Thick-film resistors can have excess noise if there is voltage across
    them, but it's hard to measure. I managed to measure some once, but it
    took very high value resistors and high voltages.

    As Kipling's Shipwrecked Mariner said to the Whale, "Not so, but far >otherwise." (At least in my business, i.e. ultrasensitive measurements,
    that is.)

    One time I was chasing my tail for about a day, trying to figure out why
    my shiny new super low noise laser driver gizmo was exhibiting horrific
    1/f noise on the spectrum analyzer. It turned out to be the classic >Tektronix 50-ohm 2-W BNC feedthrough terminator I was using--it was made
    of cermet. Switching to metal film dropped the 1/f noise by about two
    orders of magnitude IIRC. Not subtle at all.


    Was there voltage across that terminator? Was it making unusually
    large amounts of Johnson noise?



    --

    I yam what I yam - Popeye

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  • From Phil Hobbs@21:1/5 to jlarkin@highlandsniptechnology.com on Mon Mar 7 12:35:32 2022
    jlarkin@highlandsniptechnology.com wrote:
    On Mon, 7 Mar 2022 12:03:17 -0500, Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net> wrote:

    jlarkin@highlandsniptechnology.com wrote:
    On Mon, 07 Mar 2022 12:50:45 +0100, Jeroen Belleman
    <jeroen@nospam.please> wrote:

    On 2022-03-07 12:10, pavelm...@gmail.com wrote:
    Hello, colleagues

    My question is about basic component that we all
    are working with - resistor, actually SMD 0402 type of them. There
    are few technologies on the market to make them - thick film, thin
    film, metal film, and probably some more. Resistors produced by
    different technologies has different performance. Currently I am
    interested in three characteristics for 0402 size of resistors -
    parasitic parallel capacitance, parasitic series inductance, and
    generated noise, and their repeatability/stability/predictability in >>>>> production. I am talking about frequency range from DC and up to 2
    GHz. Could you provide/reveal values of these properties of 0402
    resistors made by each of above technologies? Any additional
    information will be appreciated. Thank you



    I measured parasitic capacitance and inductance for 1206 resistors
    and got about 50fF and 500pH. I'd expect about the same for 0402,
    because they have the same shape. Of course, pad layout and trace
    width matters, as does the proximity of other conductors. I only
    measured 1% metal film resistors.

    The parasitics of various resistors are easily googled.


    Common wisdom says that only metal film should be used where noise
    matters. I never made comparative measurements. In my field,
    resistor cost is relatively negligible, so I tend to use metal
    film almost everywhere.

    Jeroen Belleman

    Johnson noise must be the same regardless of the materials.

    Thick-film resistors can have excess noise if there is voltage across
    them, but it's hard to measure. I managed to measure some once, but it
    took very high value resistors and high voltages.

    As Kipling's Shipwrecked Mariner said to the Whale, "Not so, but far
    otherwise." (At least in my business, i.e. ultrasensitive measurements,
    that is.)

    One time I was chasing my tail for about a day, trying to figure out why
    my shiny new super low noise laser driver gizmo was exhibiting horrific
    1/f noise on the spectrum analyzer. It turned out to be the classic
    Tektronix 50-ohm 2-W BNC feedthrough terminator I was using--it was made
    of cermet. Switching to metal film dropped the 1/f noise by about two
    orders of magnitude IIRC. Not subtle at all.


    Was there voltage across that terminator? Was it making unusually
    large amounts of Johnson noise?

    Yes, I was pumping a couple of hundred milliamps into it. 1/f noise
    arises from conductance fluctuations, so it doesn't appear unless
    there's current flowing. As you say, Johnson noise depends only on the resistance and the temperature, but of course it also assumes thermal equilibrium, which stops applying when the power gets turned on.

    Cheers




    --
    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 Gerhard Hoffmann@21:1/5 to All on Mon Mar 7 18:57:00 2022
    Am 07.03.22 um 16:31 schrieb jlarkin@highlandsniptechnology.com:


    Johnson noise must be the same regardless of the materials.

    Thick-film resistors can have excess noise if there is voltage across
    them, but it's hard to measure. I managed to measure some once, but it
    took very high value resistors and high voltages.

    High tempco resistors in a voltage divider or equivalent can make low frequency (subsonic) noise from small temperature fluctuations.

    I have a version of Win's AOE3 ribbon microphone amplifier,
    not differential but only single-ended with an ugly coupling cap
    and 16 transistors instead of 64.

    That has a switchable ~6 Ohm resistor to get "calibration noise".
    It is easy to see.

    < https://www.flickr.com/photos/137684711@N07/44311358915/in/album-72157662535945536/
    > and left / right arrows

    My 10 * 2 * ADA4898 amplifier uses 60R as a 1nV/rtHz normal.


    Cheers, Gerhard

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  • From John Larkin@21:1/5 to pcdhSpamMeSenseless@electrooptical. on Mon Mar 7 10:16:11 2022
    On Mon, 7 Mar 2022 12:35:32 -0500, Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net> wrote:

    jlarkin@highlandsniptechnology.com wrote:
    On Mon, 7 Mar 2022 12:03:17 -0500, Phil Hobbs
    <pcdhSpamMeSenseless@electrooptical.net> wrote:

    jlarkin@highlandsniptechnology.com wrote:
    On Mon, 07 Mar 2022 12:50:45 +0100, Jeroen Belleman
    <jeroen@nospam.please> wrote:

    On 2022-03-07 12:10, pavelm...@gmail.com wrote:
    Hello, colleagues

    My question is about basic component that we all
    are working with - resistor, actually SMD 0402 type of them. There >>>>>> are few technologies on the market to make them - thick film, thin >>>>>> film, metal film, and probably some more. Resistors produced by
    different technologies has different performance. Currently I am
    interested in three characteristics for 0402 size of resistors -
    parasitic parallel capacitance, parasitic series inductance, and
    generated noise, and their repeatability/stability/predictability in >>>>>> production. I am talking about frequency range from DC and up to 2 >>>>>> GHz. Could you provide/reveal values of these properties of 0402
    resistors made by each of above technologies? Any additional
    information will be appreciated. Thank you



    I measured parasitic capacitance and inductance for 1206 resistors
    and got about 50fF and 500pH. I'd expect about the same for 0402,
    because they have the same shape. Of course, pad layout and trace
    width matters, as does the proximity of other conductors. I only
    measured 1% metal film resistors.

    The parasitics of various resistors are easily googled.


    Common wisdom says that only metal film should be used where noise
    matters. I never made comparative measurements. In my field,
    resistor cost is relatively negligible, so I tend to use metal
    film almost everywhere.

    Jeroen Belleman

    Johnson noise must be the same regardless of the materials.

    Thick-film resistors can have excess noise if there is voltage across
    them, but it's hard to measure. I managed to measure some once, but it >>>> took very high value resistors and high voltages.

    As Kipling's Shipwrecked Mariner said to the Whale, "Not so, but far
    otherwise." (At least in my business, i.e. ultrasensitive measurements, >>> that is.)

    One time I was chasing my tail for about a day, trying to figure out why >>> my shiny new super low noise laser driver gizmo was exhibiting horrific >>> 1/f noise on the spectrum analyzer. It turned out to be the classic
    Tektronix 50-ohm 2-W BNC feedthrough terminator I was using--it was made >>> of cermet. Switching to metal film dropped the 1/f noise by about two
    orders of magnitude IIRC. Not subtle at all.


    Was there voltage across that terminator? Was it making unusually
    large amounts of Johnson noise?

    Yes, I was pumping a couple of hundred milliamps into it. 1/f noise
    arises from conductance fluctuations, so it doesn't appear unless
    there's current flowing. As you say, Johnson noise depends only on the >resistance and the temperature, but of course it also assumes thermal >equilibrium, which stops applying when the power gets turned on.

    Cheers

    It's probably too late, but it would be interesting to measure the 1/f
    noise vs current. It might be square law, namely thermal.

    Thinfilms have much lower tempcos than cermets. There could be
    micro/localized thermal effects too, like at grain boundaries. Laser
    trimming can create horrors.

    I found it difficult to measure excess noise in cermets, and it was in
    the ballpark of the Johnson noise. These were megohm range values, so self-heating was negligable.

    Then it was hard to find 10M sorts of thinfilms.

    --

    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 LM@21:1/5 to All on Mon Mar 7 20:41:30 2022
    On Mon, 07 Mar 2022 09:21:55 -0800, jlarkin@highlandsniptechnology.com
    wrote:

    On Mon, 7 Mar 2022 11:38:41 -0500, Phil Hobbs ><pcdhSpamMeSenseless@electrooptical.net> wrote:

    Jeroen Belleman wrote:
    On 2022-03-07 12:10, pavelm...@gmail.com wrote:
    Hello, colleagues

    My question is about basic component that we all
    are working with - resistor, actually SMD 0402 type of them. There
    are few technologies on the market to make them - thick film, thin
    film, metal film, and probably some more. Resistors produced by
    different technologies has different performance. Currently I am
    interested in three characteristics for 0402 size of resistors -
    parasitic parallel capacitance, parasitic series inductance, and
    generated noise, and their repeatability/stability/predictability in
    production. I am talking about frequency range from DC and up to 2
    GHz. Could you provide/reveal values of these properties of 0402
    resistors made by each of above technologies? Any additional
    information will be appreciated. Thank you



    I measured parasitic capacitance and inductance for 1206 resistors
    and got about 50fF and 500pH. I'd expect about the same for 0402,
    because they have the same shape. Of course, pad layout and trace
    width matters, as does the proximity of other conductors. I only
    measured 1% metal film resistors.

    Common wisdom says that only metal film should be used where noise
    matters. I never made comparative measurements. In my field,
    resistor cost is relatively negligible, so I tend to use metal
    film almost everywhere.

    Jeroen Belleman

    Yup. Cermet, thick film, and anything with carbon in it are disastrous
    for 1/f noise. They're all pretty well equivalent at high frequency. >>("Thin film" is SMT-speak for "metal film".)

    JL made some TDR measurements of (iirc) thin film resistors and showed
    that the inductance was significantly reduced by mounting them upside
    down, so that the resistive track was next to the board.

    Cheers

    Phil Hobbs

    Regular cermets, but the geometric effects are the same.

    You can buy resistors without wrap-around end caps, intended to solder >element down.
    Digikey had several types of resistors.

    Carbon combosition
    Carbon film
    Ceramic
    Metal Element
    Metal Film
    Metal Foil
    Thich Film
    Thin Film
    Wirewound

    Last time I checked, there was only thin and thick film. That is not
    much of a choice.

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Phil Hobbs@21:1/5 to John Larkin on Mon Mar 7 14:47:04 2022
    John Larkin wrote:
    On Mon, 7 Mar 2022 12:35:32 -0500, Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net> wrote:

    jlarkin@highlandsniptechnology.com wrote:
    On Mon, 7 Mar 2022 12:03:17 -0500, Phil Hobbs
    <pcdhSpamMeSenseless@electrooptical.net> wrote:

    jlarkin@highlandsniptechnology.com wrote:
    On Mon, 07 Mar 2022 12:50:45 +0100, Jeroen Belleman
    <jeroen@nospam.please> wrote:

    On 2022-03-07 12:10, pavelm...@gmail.com wrote:
    Hello, colleagues

    My question is about basic component that we all
    are working with - resistor, actually SMD 0402 type of them. There >>>>>>> are few technologies on the market to make them - thick film, thin >>>>>>> film, metal film, and probably some more. Resistors produced by
    different technologies has different performance. Currently I am >>>>>>> interested in three characteristics for 0402 size of resistors - >>>>>>> parasitic parallel capacitance, parasitic series inductance, and >>>>>>> generated noise, and their repeatability/stability/predictability in >>>>>>> production. I am talking about frequency range from DC and up to 2 >>>>>>> GHz. Could you provide/reveal values of these properties of 0402 >>>>>>> resistors made by each of above technologies? Any additional
    information will be appreciated. Thank you



    I measured parasitic capacitance and inductance for 1206 resistors >>>>>> and got about 50fF and 500pH. I'd expect about the same for 0402,
    because they have the same shape. Of course, pad layout and trace
    width matters, as does the proximity of other conductors. I only
    measured 1% metal film resistors.

    The parasitics of various resistors are easily googled.


    Common wisdom says that only metal film should be used where noise >>>>>> matters. I never made comparative measurements. In my field,
    resistor cost is relatively negligible, so I tend to use metal
    film almost everywhere.

    Jeroen Belleman

    Johnson noise must be the same regardless of the materials.

    Thick-film resistors can have excess noise if there is voltage across >>>>> them, but it's hard to measure. I managed to measure some once, but it >>>>> took very high value resistors and high voltages.

    As Kipling's Shipwrecked Mariner said to the Whale, "Not so, but far
    otherwise." (At least in my business, i.e. ultrasensitive measurements, >>>> that is.)

    One time I was chasing my tail for about a day, trying to figure out why >>>> my shiny new super low noise laser driver gizmo was exhibiting horrific >>>> 1/f noise on the spectrum analyzer. It turned out to be the classic
    Tektronix 50-ohm 2-W BNC feedthrough terminator I was using--it was made >>>> of cermet. Switching to metal film dropped the 1/f noise by about two >>>> orders of magnitude IIRC. Not subtle at all.


    Was there voltage across that terminator? Was it making unusually
    large amounts of Johnson noise?

    Yes, I was pumping a couple of hundred milliamps into it. 1/f noise
    arises from conductance fluctuations, so it doesn't appear unless
    there's current flowing. As you say, Johnson noise depends only on the
    resistance and the temperature, but of course it also assumes thermal
    equilibrium, which stops applying when the power gets turned on.

    Cheers

    It's probably too late, but it would be interesting to measure the 1/f
    noise vs current. It might be square law, namely thermal.

    Nah, definitely linear, and definitely 1/f not 1/f**2. A constant-rate
    drift notionally has a spectrum that goes as 1/f**4, and a random-walk
    drift ('brown noise') goes as 1/f**2. That's what you usually see go
    away when you put styrofoam on top of the resistor.

    It's quite possible that the conductivity fluctuations depend on
    temperature, but I don't recall hearing that mentioned.


    Thinfilms have much lower tempcos than cermets. There could be micro/localized thermal effects too, like at grain boundaries. Laser
    trimming can create horrors.

    I found it difficult to measure excess noise in cermets, and it was in
    the ballpark of the Johnson noise. These were megohm range values, so self-heating was negligable.

    Then it was hard to find 10M sorts of thinfilms.

    Well, believe me, this example was the very furthest thing from subtle.

    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 All on Mon Mar 7 14:49:06 2022
    LM wrote:
    On Mon, 07 Mar 2022 09:21:55 -0800, jlarkin@highlandsniptechnology.com
    wrote:

    On Mon, 7 Mar 2022 11:38:41 -0500, Phil Hobbs
    <pcdhSpamMeSenseless@electrooptical.net> wrote:

    Jeroen Belleman wrote:
    On 2022-03-07 12:10, pavelm...@gmail.com wrote:
    Hello, colleagues

    My question is about basic component that we all
    are working with - resistor, actually SMD 0402 type of them. There
    are few technologies on the market to make them - thick film, thin
    film, metal film, and probably some more. Resistors produced by
    different technologies has different performance. Currently I am
    interested in three characteristics for 0402 size of resistors -
    parasitic parallel capacitance, parasitic series inductance, and
    generated noise, and their repeatability/stability/predictability in >>>>> production. I am talking about frequency range from DC and up to 2
    GHz. Could you provide/reveal values of these properties of 0402
    resistors made by each of above technologies? Any additional
    information will be appreciated. Thank you



    I measured parasitic capacitance and inductance for 1206 resistors
    and got about 50fF and 500pH. I'd expect about the same for 0402,
    because they have the same shape. Of course, pad layout and trace
    width matters, as does the proximity of other conductors. I only
    measured 1% metal film resistors.

    Common wisdom says that only metal film should be used where noise
    matters. I never made comparative measurements. In my field,
    resistor cost is relatively negligible, so I tend to use metal
    film almost everywhere.

    Jeroen Belleman

    Yup. Cermet, thick film, and anything with carbon in it are disastrous
    for 1/f noise. They're all pretty well equivalent at high frequency.
    ("Thin film" is SMT-speak for "metal film".)

    JL made some TDR measurements of (iirc) thin film resistors and showed
    that the inductance was significantly reduced by mounting them upside
    down, so that the resistive track was next to the board.

    Cheers

    Phil Hobbs

    Regular cermets, but the geometric effects are the same.

    You can buy resistors without wrap-around end caps, intended to solder
    element down.
    Digikey had several types of resistors.

    Carbon combosition
    Carbon film
    Ceramic
    Metal Element
    Metal Film
    Metal Foil
    Thich Film
    Thin Film
    Wirewound

    Last time I checked, there was only thin and thick film. That is not
    much of a choice.


    To an engineering approximation, all metal / 'thin film' resistors
    exhibit only Johnson noise.

    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 whit3rd@21:1/5 to Phil Hobbs on Mon Mar 7 13:09:19 2022
    On Monday, March 7, 2022 at 11:47:16 AM UTC-8, Phil Hobbs wrote:
    John Larkin wrote:
    On Mon, 7 Mar 2022 12:35:32 -0500, Phil Hobbs <pcdhSpamM...@electrooptical.net> wrote:

    jla...@highlandsniptechnology.com wrote:
    On Mon, 7 Mar 2022 12:03:17 -0500, Phil Hobbs
    <pcdhSpamM...@electrooptical.net> wrote:

    ...gizmo was exhibiting horrific
    1/f noise on the spectrum analyzer. It turned out to be the classic
    Tektronix 50-ohm 2-W BNC feedthrough terminator I was using--it was made >>>> of cermet. Switching to metal film dropped the 1/f noise by about two >>>> orders of magnitude IIRC. Not subtle at all.

    It's probably too late, but it would be interesting to measure the 1/f noise vs current. It might be square law, namely thermal.

    Nah, definitely linear, and definitely 1/f not 1/f**2. A constant-rate
    drift notionally has a spectrum that goes as 1/f**4, and a random-walk
    drift ('brown noise') goes as 1/f**2.

    Carbon resistors are semi-metals, so they get recombination noise; probably the 'cermet' is a similar material. For metal film, though, it's terribly difficult to
    get a thin and long continuous metal path for high resistance, AND keep it from oxidizing and changing value. So, carbon (carbon film?) still is the solution for high-ohms
    items.

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  • From pavelmargulis@gmail.com@21:1/5 to pavelm...@gmail.com on Mon Mar 7 12:32:19 2022
    On Monday, March 7, 2022 at 1:10:33 PM UTC+2, pavelm...@gmail.com wrote:
    Hello, colleagues
    My question is about basic component that we all are working with - resistor, actually SMD 0402 type of them.
    There are few technologies on the market to make them - thick film, thin film, metal film, and probably some more.
    Resistors produced by different technologies has different performance. Currently I am interested in three characteristics for 0402 size of resistors - parasitic parallel capacitance, parasitic series inductance, and generated noise, and their repeatability/stability/predictability in production. I am talking about
    frequency range from DC and up to 2 GHz.
    Could you provide/reveal values of these properties of 0402 resistors made by each of above technologies? Any additional information will be appreciated.
    Thank you

    Hello, Everybody
    I am excited to read the discussion about the influence of resistor technology on noise. It is very interesting and helpful.
    Though one of the original questions was about how 0402 resistor's parallel capacitance depends on the resistor's technology. Vishay's application paper (freqresp.pdf) talks about comparison of thin film resistors with different termination styles (wrap,
    flip ship) and their capacitance. But they are all made with thin film technology.
    They mentioned that for thin film "normal" 0402 resistors with wrap termination this C may be expected to be about 40fF. This is, of course, the resistor's own parasitic C, as I would like to believe, without taking into account the PCB and pads.
    Does anybody of you have a similar number for a comparable thick film 0402 resistor with wrap terminals? I couldn't google it, to my surprise.
    Thank you for your responses

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  • From John Larkin@21:1/5 to All on Mon Mar 7 13:26:28 2022
    On Mon, 7 Mar 2022 13:09:19 -0800 (PST), whit3rd <whit3rd@gmail.com>
    wrote:

    On Monday, March 7, 2022 at 11:47:16 AM UTC-8, Phil Hobbs wrote:
    John Larkin wrote:
    On Mon, 7 Mar 2022 12:35:32 -0500, Phil Hobbs
    <pcdhSpamM...@electrooptical.net> wrote:

    jla...@highlandsniptechnology.com wrote:
    On Mon, 7 Mar 2022 12:03:17 -0500, Phil Hobbs
    <pcdhSpamM...@electrooptical.net> wrote:

    ...gizmo was exhibiting horrific
    1/f noise on the spectrum analyzer. It turned out to be the classic
    Tektronix 50-ohm 2-W BNC feedthrough terminator I was using--it was made
    of cermet. Switching to metal film dropped the 1/f noise by about two >> >>>> orders of magnitude IIRC. Not subtle at all.

    It's probably too late, but it would be interesting to measure the 1/f
    noise vs current. It might be square law, namely thermal.

    Nah, definitely linear, and definitely 1/f not 1/f**2. A constant-rate
    drift notionally has a spectrum that goes as 1/f**4, and a random-walk
    drift ('brown noise') goes as 1/f**2.

    Carbon resistors are semi-metals, so they get recombination noise; probably >the 'cermet' is a similar material. For metal film, though, it's terribly difficult to
    get a thin and long continuous metal path for high resistance, AND keep it from
    oxidizing and changing value. So, carbon (carbon film?) still is the solution for high-ohms
    items.

    I have some 1T ohm surface-mount cermet resistors.

    --

    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 All on Mon Mar 7 16:27:20 2022
    whit3rd wrote:
    On Monday, March 7, 2022 at 11:47:16 AM UTC-8, Phil Hobbs wrote:
    John Larkin wrote:
    On Mon, 7 Mar 2022 12:35:32 -0500, Phil Hobbs
    <pcdhSpamM...@electrooptical.net> wrote:

    jla...@highlandsniptechnology.com wrote:
    On Mon, 7 Mar 2022 12:03:17 -0500, Phil Hobbs
    <pcdhSpamM...@electrooptical.net> wrote:

    ...gizmo was exhibiting horrific 1/f noise on the spectrum
    analyzer. It turned out to be the classic Tektronix 50-ohm
    2-W BNC feedthrough terminator I was using--it was made of
    cermet. Switching to metal film dropped the 1/f noise by
    about two orders of magnitude IIRC. Not subtle at all.

    It's probably too late, but it would be interesting to measure
    the 1/f noise vs current. It might be square law, namely
    thermal.

    Nah, definitely linear, and definitely 1/f not 1/f**2. A
    constant-rate drift notionally has a spectrum that goes as 1/f**4,
    and a random-walk drift ('brown noise') goes as 1/f**2.

    Carbon resistors are semi-metals, so they get recombination noise;

    Not sure what you mean by that, exactly. To get recombination noise you
    need minority carriers, no?

    probably the 'cermet' is a similar material.

    Cermets aren't homogeneous--as the name implies, they're ceramic/metal composites.

    For metal film, though, it's terribly difficult to get a thin and
    long continuous metal path for high resistance,

    Why so? I used to make conducting films of 100 angstroms or so. Atoms
    are pretty small, and using sputtering as opposed to directional
    evaporation will make the film follow even rough substrates pretty well.

    AND keep it from oxidizing and changing value. > So, carbon (carbon
    film?) still is the solution for high-ohms items.

    It's certainly true that it's harder to make very high resistances out
    of very low resistance materials, and there are lots of low-precision applications where 1/f noise is not a serious issue--overvoltage
    protection, for instance.

    However, carbon resistors are seriously nonlinear at high voltages--the resistance of old style Allen-Bradley carbon comps was allowed to drop
    by a quarter at their upper voltage limit.

    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 Allison@21:1/5 to jla...@highlandsniptechnology.com on Mon Mar 7 13:56:36 2022
    jla...@highlandsniptechnology.com wrote:
    ================================

    Johnson noise must be the same regardless of the materials.

    ** A simple fact overwhealmed by persistent myth to the contrary.

    Thick-film resistors can have excess noise if there is voltage across
    them, but it's hard to measure.

    ** No it isn't.

    I managed to measure some once, but it
    took very high value resistors and high voltages.

    ** Drivel.

    Easy enough to characterise carbon film, carbon comp, metal glaze & MF types with values of say 100K and few DC volts.
    JL does not underdstand audio.


    ...... Phil

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  • From Phil Allison@21:1/5 to Phil Hobbs on Mon Mar 7 14:06:21 2022
    Phil Hobbs wrote:
    ==============

    However, carbon resistors are seriously nonlinear at high voltages--the resistance of old style Allen-Bradley carbon comps was allowed to drop
    by a quarter at their upper voltage limit.


    ** Really ????
    That is massively ambiguous.

    CC resistors can drop in value if they run hot and over time.
    Mostly they slowly drift high, over a period of decades.

    Crazy to crazy that " non linearity".


    ..... Phil

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  • From John Larkin@21:1/5 to pallison49@gmail.com on Mon Mar 7 14:08:20 2022
    On Mon, 7 Mar 2022 13:56:36 -0800 (PST), Phil Allison
    <pallison49@gmail.com> wrote:

    jla...@highlandsniptechnology.com wrote:
    ================================

    Johnson noise must be the same regardless of the materials.

    ** A simple fact overwhealmed by persistent myth to the contrary.

    Thick-film resistors can have excess noise if there is voltage across
    them, but it's hard to measure.

    ** No it isn't.


    https://tinyurl.com/y89rmtk3

    First paragraph.



    I managed to measure some once, but it
    took very high value resistors and high voltages.

    ** Drivel.

    Easy enough to characterise carbon film, carbon comp, metal glaze & MF types with values of say 100K and few DC volts.

    Got some measurements?

    JL does not underdstand audio.

    Well, my hearing is terrible, especially below 10 Hz.

    --

    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 Allison@21:1/5 to John Larkin on Mon Mar 7 14:53:48 2022
    John Larkin wrote:
    ================

    Johnson noise must be the same regardless of the materials.

    ** A simple fact overwhealmed by persistent myth to the contrary.

    Thick-film resistors can have excess noise if there is voltage across
    them, but it's hard to measure.

    ** No it isn't.

    https://tinyurl.com/y89rmtk3

    First paragraph.

    ** Yawnnnnnnn ....

    How pathetic.

    I managed to measure some once, but it
    took very high value resistors and high voltages.

    ** Drivel.

    Easy enough to characterise carbon film, carbon comp, metal glaze & MF types with values of say 100K and few DC volts.

    Got some measurements?

    ** Published them years ago.

    The excess noise as voltage was applied ( up to 20V) was marked, except for MF types

    JL does not underdstand audio.

    Well, my hearing is terrible,

    ** And all your other senses too.

    especially below 10 Hz.


    ** Not audio.

    Wot a tedious fuckhead.


    ..... Phil

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  • From John Larkin@21:1/5 to pallison49@gmail.com on Mon Mar 7 14:52:10 2022
    On Mon, 7 Mar 2022 14:06:21 -0800 (PST), Phil Allison
    <pallison49@gmail.com> wrote:

    Phil Hobbs wrote:
    ==============

    However, carbon resistors are seriously nonlinear at high voltages--the
    resistance of old style Allen-Bradley carbon comps was allowed to drop
    by a quarter at their upper voltage limit.


    ** Really ????
    That is massively ambiguous.

    CC resistors can drop in value if they run hot and over time.
    Mostly they slowly drift high, over a period of decades.

    Crazy to crazy that " non linearity".


    ..... Phil

    google resistor voltage coefficient

    Carbons can be ballpark 100 PPM/volt.

    --

    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 Allison@21:1/5 to John Larkin bullshitted as usual on Mon Mar 7 15:07:49 2022
    John Larkin bullshitted as usual wrote:
    ================================

    Phil Hobbs wrote:
    ==============

    However, carbon resistors are seriously nonlinear at high voltages--the
    resistance of old style Allen-Bradley carbon comps was allowed to drop
    by a quarter at their upper voltage limit.


    ** Really ????

    That is massively ambiguous.

    CC resistors can drop in value if they run hot and over time.
    Mostly they slowly drift high, over a period of decades.

    Crazy to crazy that " non linearity".


    google resistor voltage coefficient

    ** Google " arrogant fuckwit " - see yourself described.


    Carbons can be ballpark 100 PPM/volt.

    ** But are in fact not.


    ..... Phil

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  • From John Larkin@21:1/5 to pallison49@gmail.com on Mon Mar 7 17:16:50 2022
    On Mon, 7 Mar 2022 15:07:49 -0800 (PST), Phil Allison
    <pallison49@gmail.com> wrote:

    John Larkin bullshitted as usual wrote:
    ================================

    Phil Hobbs wrote:
    ==============

    However, carbon resistors are seriously nonlinear at high voltages--the >> >> resistance of old style Allen-Bradley carbon comps was allowed to drop
    by a quarter at their upper voltage limit.


    ** Really ????

    That is massively ambiguous.

    CC resistors can drop in value if they run hot and over time.
    Mostly they slowly drift high, over a period of decades.

    Crazy to crazy that " non linearity".


    google resistor voltage coefficient

    ** Google " arrogant fuckwit " - see yourself described.


    Carbons can be ballpark 100 PPM/volt.

    ** But are in fact not.


    ..... Phil

    Comps can be 200.

    In a tube amp with, say, a 50 volt p-p swing, that could be 10000 PPM
    gain change, 1% distortion. That's almost enough to hear.

    --

    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 pallison49@gmail.com on Mon Mar 7 17:18:34 2022
    On Mon, 7 Mar 2022 14:53:48 -0800 (PST), Phil Allison
    <pallison49@gmail.com> wrote:

    John Larkin wrote:
    ================

    Johnson noise must be the same regardless of the materials.

    ** A simple fact overwhealmed by persistent myth to the contrary.

    Thick-film resistors can have excess noise if there is voltage across
    them, but it's hard to measure.

    ** No it isn't.

    https://tinyurl.com/y89rmtk3

    First paragraph.

    ** Yawnnnnnnn ....

    How pathetic.

    I managed to measure some once, but it
    took very high value resistors and high voltages.

    ** Drivel.

    Easy enough to characterise carbon film, carbon comp, metal glaze & MF types with values of say 100K and few DC volts.

    Got some measurements?

    ** Published them years ago.

    The excess noise as voltage was applied ( up to 20V) was marked, except for MF types

    JL does not underdstand audio.

    Well, my hearing is terrible,

    ** And all your other senses too.

    especially below 10 Hz.


    ** Not audio.

    Wot a tedious fuckhead.

    I'm having fun. Are you?

    --

    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 whit3rd@21:1/5 to Phil Hobbs on Mon Mar 7 18:34:36 2022
    On Monday, March 7, 2022 at 1:27:34 PM UTC-8, Phil Hobbs wrote:
    whit3rd wrote:

    Carbon resistors are semi-metals, so they get recombination noise;

    Not sure what you mean by that, exactly. To get recombination noise you
    need minority carriers, no?

    probably the 'cermet' is a similar material.

    Cermets aren't homogeneous--as the name implies, they're ceramic/metal composites.

    Semi-metals are semiconductors, but at or near their intrinsic temperatures.
    A bunch of metal shavings in a tube, if shaken, has enough Shottky rectification
    at the contact points to be an RF detector (coherer was the antique radio term).
    Ceramics or metal oxides, with metal, are going to have minority carriers.
    At each metal connection, you get carrier injection.

    For metal film, though, it's terribly difficult to get a thin and
    long continuous metal path for high resistance,

    Why so? I used to make conducting films of 100 angstroms or so. Atoms
    are pretty small, and using sputtering as opposed to directional
    evaporation will make the film follow even rough substrates pretty well.

    AND keep it from oxidizing and changing value. > So, carbon (carbon
    film?) still is the solution for high-ohms items.

    Carbon resistors, especially in presence of ozone, drift to higher values because the carbon slowly turns to CO or CO2. Metals also grow oxide skins (some more quickly than others). Substrate, metal, and glaze (or at least lacquer) plus
    two solderable connections... a complete surface mount resistor packs a lot of engineering into that little package.

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  • From Phil Allison@21:1/5 to John Larkin bullshitted as usual on Mon Mar 7 18:41:01 2022
    John Larkin bullshitted as usual wrote:
    ================================

    Phil Hobbs wrote bullshit too:
    ==================

    However, carbon resistors are seriously nonlinear at high voltages--the >> >> resistance of old style Allen-Bradley carbon comps was allowed to drop >> >> by a quarter at their upper voltage limit.


    ** Really ????

    That is massively ambiguous.

    CC resistors can drop in value if they run hot and over time.
    Mostly they slowly drift high, over a period of decades.

    Crazy to crazy that " non linearity".


    google resistor voltage coefficient

    ** Google " arrogant fuckwit " - see yourself described.


    Carbons can be ballpark 100 PPM/volt.

    ** But are in fact not.


    Comps can be 200.


    ** Bullshit

    In a tube amp with, say, a 50 volt p-p swing, that could be 10000 PPM
    gain change, 1% distortion.

    ** Made up, absolute crap !!!!
    ----------------------------------------------- -----------------------------------------------

    Just to refute JL's rampant insanity - I carried a test:
    With a sine wave at 1KHz feeding a small toroidal supply tranny in reverse.
    Max available = 250Vrms at 0.05% THD.

    A pair of MF resistors ( 100k and 1k ) in series showed only residual THD across the 1k.
    Change the 100k to a ( very old ) 0.5W CC and the THD reading was then 0.33% Drop the input level to 50V rms and the reading was 0.07%.

    250V rms = 705 V p-p.
    50V rms = 141V p-p.

    FYI

    One cannot test the * lineartiy * using DC voltages.
    Cos the damn things heat and drop value by several %.



    ..... Phil

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  • From John S@21:1/5 to Phil Hobbs on Mon Mar 7 21:18:05 2022
    On 3/7/2022 3:27 PM, Phil Hobbs wrote:
    whit3rd wrote:
    On Monday, March 7, 2022 at 11:47:16 AM UTC-8, Phil Hobbs wrote:
    John Larkin wrote:
    On Mon, 7 Mar 2022 12:35:32 -0500, Phil Hobbs
    <pcdhSpamM...@electrooptical.net> wrote:

    jla...@highlandsniptechnology.com wrote:
    On Mon, 7 Mar 2022 12:03:17 -0500, Phil Hobbs
    <pcdhSpamM...@electrooptical.net> wrote:

    ...gizmo was exhibiting horrific 1/f noise on the spectrum
    analyzer. It turned out to be the classic Tektronix 50-ohm 2-W
    BNC feedthrough terminator I was using--it was made of cermet.
    Switching to metal film dropped the 1/f noise by about two orders >>>>>>> of magnitude IIRC. Not subtle at all.

    It's probably too late, but it would be interesting to measure the
    1/f noise vs current. It might be square law, namely thermal.

    Nah, definitely linear, and definitely 1/f not 1/f**2. A
    constant-rate drift notionally has a spectrum that goes as 1/f**4,
    and a random-walk drift ('brown noise') goes as 1/f**2.

    Carbon resistors are semi-metals, so they get recombination  noise;

    Not sure what you mean by that, exactly. To get recombination noise you
    need minority carriers, no?

    probably the 'cermet' is a similar material.

    Cermets aren't homogeneous--as the name implies, they're ceramic/metal composites.

    For  metal film, though, it's terribly difficult to get a thin and
    long continuous metal path for high resistance,

    Why so?  I used to make conducting films of 100 angstroms or so.  Atoms
    are pretty small, and using sputtering as opposed to directional
    evaporation will make the film follow even rough substrates pretty well.

    AND keep it from oxidizing and changing value.    > So, carbon (carbon
    film?) still is the solution for high-ohms items.

    It's certainly true that it's harder to make very high resistances out
    of very low resistance materials, and there are lots of low-precision applications where 1/f noise is not a serious issue--overvoltage
    protection, for instance.

    However, carbon resistors are seriously nonlinear at high voltages--the resistance of old style Allen-Bradley carbon comps was allowed to drop
    by a quarter at their upper voltage limit.

    Cheers

    Phil Hobbs


    Yes! I learned that the hard way. Decided I was gonna make my own HV
    divider from a string of 22meg CC resistors. I was astonished by the
    change in resistance with voltage. So I made a new scale for the meter.

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From jlarkin@highlandsniptechnology.com@21:1/5 to pallison49@gmail.com on Tue Mar 8 02:46:38 2022
    On Mon, 7 Mar 2022 18:41:01 -0800 (PST), Phil Allison
    <pallison49@gmail.com> wrote:

    John Larkin bullshitted as usual wrote:
    ================================

    Phil Hobbs wrote bullshit too:
    ==================

    However, carbon resistors are seriously nonlinear at high voltages--the
    resistance of old style Allen-Bradley carbon comps was allowed to drop >> >> >> by a quarter at their upper voltage limit.


    ** Really ????

    That is massively ambiguous.

    CC resistors can drop in value if they run hot and over time.
    Mostly they slowly drift high, over a period of decades.

    Crazy to crazy that " non linearity".


    google resistor voltage coefficient

    ** Google " arrogant fuckwit " - see yourself described.


    Carbons can be ballpark 100 PPM/volt.

    ** But are in fact not.


    Comps can be 200.


    ** Bullshit

    In a tube amp with, say, a 50 volt p-p swing, that could be 10000 PPM
    gain change, 1% distortion.

    ** Made up, absolute crap !!!! >----------------------------------------------- >-----------------------------------------------

    Just to refute JL's rampant insanity - I carried a test:
    With a sine wave at 1KHz feeding a small toroidal supply tranny in reverse. >Max available = 250Vrms at 0.05% THD.

    A pair of MF resistors ( 100k and 1k ) in series showed only residual THD across the 1k.
    Change the 100k to a ( very old ) 0.5W CC and the THD reading was then 0.33% >Drop the input level to 50V rms and the reading was 0.07%.

    250V rms = 705 V p-p.
    50V rms = 141V p-p.

    FYI

    One cannot test the * lineartiy * using DC voltages.
    Cos the damn things heat and drop value by several %.



    ..... Phil

    I said "comps", meaning carbon composition. We were talking about
    carbon resistors.





    --

    I yam what I yam - Popeye

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From jlarkin@highlandsniptechnology.com@21:1/5 to John S on Tue Mar 8 02:51:09 2022
    On Mon, 7 Mar 2022 21:18:05 -0600, John S <Sophi.2@invalid.org> wrote:

    On 3/7/2022 3:27 PM, Phil Hobbs wrote:
    whit3rd wrote:
    On Monday, March 7, 2022 at 11:47:16 AM UTC-8, Phil Hobbs wrote:
    John Larkin wrote:
    On Mon, 7 Mar 2022 12:35:32 -0500, Phil Hobbs
    <pcdhSpamM...@electrooptical.net> wrote:

    jla...@highlandsniptechnology.com wrote:
    On Mon, 7 Mar 2022 12:03:17 -0500, Phil Hobbs
    <pcdhSpamM...@electrooptical.net> wrote:

    ...gizmo was exhibiting horrific 1/f noise on the spectrum
    analyzer. It turned out to be the classic Tektronix 50-ohm 2-W >>>>>>>> BNC feedthrough terminator I was using--it was made of cermet. >>>>>>>> Switching to metal film dropped the 1/f noise by about two orders >>>>>>>> of magnitude IIRC. Not subtle at all.

    It's probably too late, but it would be interesting to measure the
    1/f noise vs current. It might be square law, namely thermal.

    Nah, definitely linear, and definitely 1/f not 1/f**2. A
    constant-rate drift notionally has a spectrum that goes as 1/f**4,
    and a random-walk drift ('brown noise') goes as 1/f**2.

    Carbon resistors are semi-metals, so they get recombination noise;

    Not sure what you mean by that, exactly. To get recombination noise you
    need minority carriers, no?

    probably the 'cermet' is a similar material.

    Cermets aren't homogeneous--as the name implies, they're ceramic/metal
    composites.

    For metal film, though, it's terribly difficult to get a thin and
    long continuous metal path for high resistance,

    Why so? I used to make conducting films of 100 angstroms or so. Atoms
    are pretty small, and using sputtering as opposed to directional
    evaporation will make the film follow even rough substrates pretty well.

    AND keep it from oxidizing and changing value. > So, carbon (carbon
    film?) still is the solution for high-ohms items.

    It's certainly true that it's harder to make very high resistances out
    of very low resistance materials, and there are lots of low-precision
    applications where 1/f noise is not a serious issue--overvoltage
    protection, for instance.

    However, carbon resistors are seriously nonlinear at high voltages--the
    resistance of old style Allen-Bradley carbon comps was allowed to drop
    by a quarter at their upper voltage limit.

    Cheers

    Phil Hobbs


    Yes! I learned that the hard way. Decided I was gonna make my own HV
    divider from a string of 22meg CC resistors. I was astonished by the
    change in resistance with voltage. So I made a new scale for the meter.

    In a divider made from a string of identical resistors, the
    nonlinearity cancels. That's why the best dividers are all on the same substrate.



    --

    I yam what I yam - Popeye

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From John Walliker@21:1/5 to jla...@highlandsniptechnology.com on Tue Mar 8 03:46:03 2022
    On Tuesday, 8 March 2022 at 10:51:26 UTC, jla...@highlandsniptechnology.com wrote:
    On Mon, 7 Mar 2022 21:18:05 -0600, John S <Sop...@invalid.org> wrote:

    On 3/7/2022 3:27 PM, Phil Hobbs wrote:
    whit3rd wrote:
    On Monday, March 7, 2022 at 11:47:16 AM UTC-8, Phil Hobbs wrote:
    John Larkin wrote:
    On Mon, 7 Mar 2022 12:35:32 -0500, Phil Hobbs
    <pcdhSpamM...@electrooptical.net> wrote:

    jla...@highlandsniptechnology.com wrote:
    On Mon, 7 Mar 2022 12:03:17 -0500, Phil Hobbs
    <pcdhSpamM...@electrooptical.net> wrote:

    ...gizmo was exhibiting horrific 1/f noise on the spectrum
    analyzer. It turned out to be the classic Tektronix 50-ohm 2-W >>>>>>>> BNC feedthrough terminator I was using--it was made of cermet. >>>>>>>> Switching to metal film dropped the 1/f noise by about two orders >>>>>>>> of magnitude IIRC. Not subtle at all.

    It's probably too late, but it would be interesting to measure the >>>>> 1/f noise vs current. It might be square law, namely thermal.

    Nah, definitely linear, and definitely 1/f not 1/f**2. A
    constant-rate drift notionally has a spectrum that goes as 1/f**4,
    and a random-walk drift ('brown noise') goes as 1/f**2.

    Carbon resistors are semi-metals, so they get recombination noise;

    Not sure what you mean by that, exactly. To get recombination noise you
    need minority carriers, no?

    probably the 'cermet' is a similar material.

    Cermets aren't homogeneous--as the name implies, they're ceramic/metal
    composites.

    For metal film, though, it's terribly difficult to get a thin and
    long continuous metal path for high resistance,

    Why so? I used to make conducting films of 100 angstroms or so. Atoms
    are pretty small, and using sputtering as opposed to directional
    evaporation will make the film follow even rough substrates pretty well. >>
    AND keep it from oxidizing and changing value. > So, carbon (carbon >>> film?) still is the solution for high-ohms items.

    It's certainly true that it's harder to make very high resistances out
    of very low resistance materials, and there are lots of low-precision
    applications where 1/f noise is not a serious issue--overvoltage
    protection, for instance.

    However, carbon resistors are seriously nonlinear at high voltages--the
    resistance of old style Allen-Bradley carbon comps was allowed to drop
    by a quarter at their upper voltage limit.

    Cheers

    Phil Hobbs


    Yes! I learned that the hard way. Decided I was gonna make my own HV >divider from a string of 22meg CC resistors. I was astonished by the
    change in resistance with voltage. So I made a new scale for the meter.
    In a divider made from a string of identical resistors, the
    nonlinearity cancels. That's why the best dividers are all on the same substrate.
    --

    I yam what I yam - Popeye

    The long-term resistance shift doesn't behave that way at high voltages, because the ones at the top of the string suffer more corona discharge which can therefore erode them faster. I found this out the hard way.

    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 Mar 8 07:39:29 2022
    On Tue, 8 Mar 2022 03:46:03 -0800 (PST), John Walliker
    <jrwalliker@gmail.com> wrote:

    On Tuesday, 8 March 2022 at 10:51:26 UTC, jla...@highlandsniptechnology.com wrote:
    On Mon, 7 Mar 2022 21:18:05 -0600, John S <Sop...@invalid.org> wrote:

    On 3/7/2022 3:27 PM, Phil Hobbs wrote:
    whit3rd wrote:
    On Monday, March 7, 2022 at 11:47:16 AM UTC-8, Phil Hobbs wrote:
    John Larkin wrote:
    On Mon, 7 Mar 2022 12:35:32 -0500, Phil Hobbs
    <pcdhSpamM...@electrooptical.net> wrote:

    jla...@highlandsniptechnology.com wrote:
    On Mon, 7 Mar 2022 12:03:17 -0500, Phil Hobbs
    <pcdhSpamM...@electrooptical.net> wrote:

    ...gizmo was exhibiting horrific 1/f noise on the spectrum
    analyzer. It turned out to be the classic Tektronix 50-ohm 2-W
    BNC feedthrough terminator I was using--it was made of cermet.
    Switching to metal film dropped the 1/f noise by about two orders >> >>>>>>>> of magnitude IIRC. Not subtle at all.

    It's probably too late, but it would be interesting to measure the
    1/f noise vs current. It might be square law, namely thermal.

    Nah, definitely linear, and definitely 1/f not 1/f**2. A
    constant-rate drift notionally has a spectrum that goes as 1/f**4,
    and a random-walk drift ('brown noise') goes as 1/f**2.

    Carbon resistors are semi-metals, so they get recombination noise;

    Not sure what you mean by that, exactly. To get recombination noise you >> >> need minority carriers, no?

    probably the 'cermet' is a similar material.

    Cermets aren't homogeneous--as the name implies, they're ceramic/metal
    composites.

    For metal film, though, it's terribly difficult to get a thin and
    long continuous metal path for high resistance,

    Why so? I used to make conducting films of 100 angstroms or so. Atoms >> >> are pretty small, and using sputtering as opposed to directional
    evaporation will make the film follow even rough substrates pretty well. >> >>
    AND keep it from oxidizing and changing value. > So, carbon (carbon >> >>> film?) still is the solution for high-ohms items.

    It's certainly true that it's harder to make very high resistances out
    of very low resistance materials, and there are lots of low-precision
    applications where 1/f noise is not a serious issue--overvoltage
    protection, for instance.

    However, carbon resistors are seriously nonlinear at high voltages--the >> >> resistance of old style Allen-Bradley carbon comps was allowed to drop
    by a quarter at their upper voltage limit.

    Cheers

    Phil Hobbs


    Yes! I learned that the hard way. Decided I was gonna make my own HV
    divider from a string of 22meg CC resistors. I was astonished by the
    change in resistance with voltage. So I made a new scale for the meter.
    In a divider made from a string of identical resistors, the
    nonlinearity cancels. That's why the best dividers are all on the same
    substrate.
    --

    I yam what I yam - Popeye

    The long-term resistance shift doesn't behave that way at high voltages, >because the ones at the top of the string suffer more corona discharge which >can therefore erode them faster. I found this out the hard way.

    John

    I guess it should be coated or potted or something.

    Ww have a potential customer who wants a 1500 volt power supply
    programmable and stable to 1 PPM. That could get interesting.

    Some sort of shield could prevent corona. But 1500v isn't bad.





    --

    I yam what I yam - Popeye

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From John S@21:1/5 to jlarkin@highlandsniptechnology.com on Tue Mar 8 09:54:29 2022
    On 3/8/2022 4:51 AM, jlarkin@highlandsniptechnology.com wrote:
    On Mon, 7 Mar 2022 21:18:05 -0600, John S <Sophi.2@invalid.org> wrote:

    On 3/7/2022 3:27 PM, Phil Hobbs wrote:
    whit3rd wrote:
    On Monday, March 7, 2022 at 11:47:16 AM UTC-8, Phil Hobbs wrote:
    John Larkin wrote:
    On Mon, 7 Mar 2022 12:35:32 -0500, Phil Hobbs
    <pcdhSpamM...@electrooptical.net> wrote:

    jla...@highlandsniptechnology.com wrote:
    On Mon, 7 Mar 2022 12:03:17 -0500, Phil Hobbs
    <pcdhSpamM...@electrooptical.net> wrote:

    ...gizmo was exhibiting horrific 1/f noise on the spectrum
    analyzer. It turned out to be the classic Tektronix 50-ohm 2-W >>>>>>>>> BNC feedthrough terminator I was using--it was made of cermet. >>>>>>>>> Switching to metal film dropped the 1/f noise by about two orders >>>>>>>>> of magnitude IIRC. Not subtle at all.

    It's probably too late, but it would be interesting to measure the >>>>>> 1/f noise vs current. It might be square law, namely thermal.

    Nah, definitely linear, and definitely 1/f not 1/f**2. A
    constant-rate drift notionally has a spectrum that goes as 1/f**4,
    and a random-walk drift ('brown noise') goes as 1/f**2.

    Carbon resistors are semi-metals, so they get recombination  noise;

    Not sure what you mean by that, exactly. To get recombination noise you
    need minority carriers, no?

    probably the 'cermet' is a similar material.

    Cermets aren't homogeneous--as the name implies, they're ceramic/metal
    composites.

    For  metal film, though, it's terribly difficult to get a thin and
    long continuous metal path for high resistance,

    Why so?  I used to make conducting films of 100 angstroms or so.  Atoms >>> are pretty small, and using sputtering as opposed to directional
    evaporation will make the film follow even rough substrates pretty well. >>>
    AND keep it from oxidizing and changing value.    > So, carbon (carbon >>>> film?) still is the solution for high-ohms items.

    It's certainly true that it's harder to make very high resistances out
    of very low resistance materials, and there are lots of low-precision
    applications where 1/f noise is not a serious issue--overvoltage
    protection, for instance.

    However, carbon resistors are seriously nonlinear at high voltages--the
    resistance of old style Allen-Bradley carbon comps was allowed to drop
    by a quarter at their upper voltage limit.

    Cheers

    Phil Hobbs


    Yes! I learned that the hard way. Decided I was gonna make my own HV
    divider from a string of 22meg CC resistors. I was astonished by the
    change in resistance with voltage. So I made a new scale for the meter.

    In a divider made from a string of identical resistors, the
    nonlinearity cancels. That's why the best dividers are all on the same substrate.


    No, I don't think so. The resistors all have a negative voltage
    coefficient and they add in a string.

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From jlarkin@highlandsniptechnology.com@21:1/5 to John S on Tue Mar 8 08:04:38 2022
    On Tue, 8 Mar 2022 09:54:29 -0600, John S <Sophi.2@invalid.org> wrote:

    On 3/8/2022 4:51 AM, jlarkin@highlandsniptechnology.com wrote:
    On Mon, 7 Mar 2022 21:18:05 -0600, John S <Sophi.2@invalid.org> wrote:

    On 3/7/2022 3:27 PM, Phil Hobbs wrote:
    whit3rd wrote:
    On Monday, March 7, 2022 at 11:47:16 AM UTC-8, Phil Hobbs wrote:
    John Larkin wrote:
    On Mon, 7 Mar 2022 12:35:32 -0500, Phil Hobbs
    <pcdhSpamM...@electrooptical.net> wrote:

    jla...@highlandsniptechnology.com wrote:
    On Mon, 7 Mar 2022 12:03:17 -0500, Phil Hobbs
    <pcdhSpamM...@electrooptical.net> wrote:

    ...gizmo was exhibiting horrific 1/f noise on the spectrum >>>>>>>>>> analyzer. It turned out to be the classic Tektronix 50-ohm 2-W >>>>>>>>>> BNC feedthrough terminator I was using--it was made of cermet. >>>>>>>>>> Switching to metal film dropped the 1/f noise by about two orders >>>>>>>>>> of magnitude IIRC. Not subtle at all.

    It's probably too late, but it would be interesting to measure the >>>>>>> 1/f noise vs current. It might be square law, namely thermal.

    Nah, definitely linear, and definitely 1/f not 1/f**2. A
    constant-rate drift notionally has a spectrum that goes as 1/f**4, >>>>>> and a random-walk drift ('brown noise') goes as 1/f**2.

    Carbon resistors are semi-metals, so they get recombination noise;

    Not sure what you mean by that, exactly. To get recombination noise you >>>> need minority carriers, no?

    probably the 'cermet' is a similar material.

    Cermets aren't homogeneous--as the name implies, they're ceramic/metal >>>> composites.

    For metal film, though, it's terribly difficult to get a thin and
    long continuous metal path for high resistance,

    Why so? I used to make conducting films of 100 angstroms or so. Atoms >>>> are pretty small, and using sputtering as opposed to directional
    evaporation will make the film follow even rough substrates pretty well. >>>>
    AND keep it from oxidizing and changing value. > So, carbon (carbon >>>>> film?) still is the solution for high-ohms items.

    It's certainly true that it's harder to make very high resistances out >>>> of very low resistance materials, and there are lots of low-precision
    applications where 1/f noise is not a serious issue--overvoltage
    protection, for instance.

    However, carbon resistors are seriously nonlinear at high voltages--the >>>> resistance of old style Allen-Bradley carbon comps was allowed to drop >>>> by a quarter at their upper voltage limit.

    Cheers

    Phil Hobbs


    Yes! I learned that the hard way. Decided I was gonna make my own HV
    divider from a string of 22meg CC resistors. I was astonished by the
    change in resistance with voltage. So I made a new scale for the meter.

    In a divider made from a string of identical resistors, the
    nonlinearity cancels. That's why the best dividers are all on the same
    substrate.


    No, I don't think so. The resistors all have a negative voltage
    coefficient and they add in a string.

    Given 10 identical resistors in series, each drops 1/10 of the total
    voltage.



    --

    I yam what I yam - Popeye

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From John S@21:1/5 to jlarkin@highlandsniptechnology.com on Tue Mar 8 10:09:13 2022
    On 3/8/2022 10:04 AM, jlarkin@highlandsniptechnology.com wrote:
    On Tue, 8 Mar 2022 09:54:29 -0600, John S <Sophi.2@invalid.org> wrote:

    On 3/8/2022 4:51 AM, jlarkin@highlandsniptechnology.com wrote:
    On Mon, 7 Mar 2022 21:18:05 -0600, John S <Sophi.2@invalid.org> wrote:

    On 3/7/2022 3:27 PM, Phil Hobbs wrote:
    whit3rd wrote:
    On Monday, March 7, 2022 at 11:47:16 AM UTC-8, Phil Hobbs wrote:
    John Larkin wrote:
    On Mon, 7 Mar 2022 12:35:32 -0500, Phil Hobbs
    <pcdhSpamM...@electrooptical.net> wrote:

    jla...@highlandsniptechnology.com wrote:
    On Mon, 7 Mar 2022 12:03:17 -0500, Phil Hobbs
    <pcdhSpamM...@electrooptical.net> wrote:

    ...gizmo was exhibiting horrific 1/f noise on the spectrum >>>>>>>>>>> analyzer. It turned out to be the classic Tektronix 50-ohm 2-W >>>>>>>>>>> BNC feedthrough terminator I was using--it was made of cermet. >>>>>>>>>>> Switching to metal film dropped the 1/f noise by about two orders >>>>>>>>>>> of magnitude IIRC. Not subtle at all.

    It's probably too late, but it would be interesting to measure the >>>>>>>> 1/f noise vs current. It might be square law, namely thermal.

    Nah, definitely linear, and definitely 1/f not 1/f**2. A
    constant-rate drift notionally has a spectrum that goes as 1/f**4, >>>>>>> and a random-walk drift ('brown noise') goes as 1/f**2.

    Carbon resistors are semi-metals, so they get recombination  noise; >>>>>
    Not sure what you mean by that, exactly. To get recombination noise you >>>>> need minority carriers, no?

    probably the 'cermet' is a similar material.

    Cermets aren't homogeneous--as the name implies, they're ceramic/metal >>>>> composites.

    For  metal film, though, it's terribly difficult to get a thin and >>>>>> long continuous metal path for high resistance,

    Why so?  I used to make conducting films of 100 angstroms or so.  Atoms >>>>> are pretty small, and using sputtering as opposed to directional
    evaporation will make the film follow even rough substrates pretty well. >>>>>
    AND keep it from oxidizing and changing value.    > So, carbon (carbon
    film?) still is the solution for high-ohms items.

    It's certainly true that it's harder to make very high resistances out >>>>> of very low resistance materials, and there are lots of low-precision >>>>> applications where 1/f noise is not a serious issue--overvoltage
    protection, for instance.

    However, carbon resistors are seriously nonlinear at high voltages--the >>>>> resistance of old style Allen-Bradley carbon comps was allowed to drop >>>>> by a quarter at their upper voltage limit.

    Cheers

    Phil Hobbs


    Yes! I learned that the hard way. Decided I was gonna make my own HV
    divider from a string of 22meg CC resistors. I was astonished by the
    change in resistance with voltage. So I made a new scale for the meter. >>>
    In a divider made from a string of identical resistors, the
    nonlinearity cancels. That's why the best dividers are all on the same
    substrate.


    No, I don't think so. The resistors all have a negative voltage
    coefficient and they add in a string.

    Given 10 identical resistors in series, each drops 1/10 of the total
    voltage.


    Yes. But the resistance at rated voltage is much lower than it is at a
    couple of volts.

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Phil Hobbs@21:1/5 to John S on Tue Mar 8 11:31:42 2022
    John S wrote:
    On 3/8/2022 4:51 AM, jlarkin@highlandsniptechnology.com wrote:
    On Mon, 7 Mar 2022 21:18:05 -0600, John S <Sophi.2@invalid.org> wrote:

    On 3/7/2022 3:27 PM, Phil Hobbs wrote:
    whit3rd wrote:
    On Monday, March 7, 2022 at 11:47:16 AM UTC-8, Phil Hobbs wrote:
    John Larkin wrote:
    On Mon, 7 Mar 2022 12:35:32 -0500, Phil Hobbs
    <pcdhSpamM...@electrooptical.net> wrote:

    jla...@highlandsniptechnology.com wrote:
    On Mon, 7 Mar 2022 12:03:17 -0500, Phil Hobbs
    <pcdhSpamM...@electrooptical.net> wrote:

    ...gizmo was exhibiting horrific 1/f noise on the spectrum >>>>>>>>>> analyzer. It turned out to be the classic Tektronix 50-ohm 2-W >>>>>>>>>> BNC feedthrough terminator I was using--it was made of cermet. >>>>>>>>>> Switching to metal film dropped the 1/f noise by about two orders >>>>>>>>>> of magnitude IIRC. Not subtle at all.

    It's probably too late, but it would be interesting to measure the >>>>>>> 1/f noise vs current. It might be square law, namely thermal.

    Nah, definitely linear, and definitely 1/f not 1/f**2. A
    constant-rate drift notionally has a spectrum that goes as 1/f**4, >>>>>> and a random-walk drift ('brown noise') goes as 1/f**2.

    Carbon resistors are semi-metals, so they get recombination  noise;

    Not sure what you mean by that, exactly. To get recombination noise you >>>> need minority carriers, no?

    probably the 'cermet' is a similar material.

    Cermets aren't homogeneous--as the name implies, they're ceramic/metal >>>> composites.

    For  metal film, though, it's terribly difficult to get a thin and
    long continuous metal path for high resistance,

    Why so?  I used to make conducting films of 100 angstroms or so.  Atoms >>>> are pretty small, and using sputtering as opposed to directional
    evaporation will make the film follow even rough substrates pretty
    well.

    AND keep it from oxidizing and changing value.    > So, carbon (carbon >>>>> film?) still is the solution for high-ohms items.

    It's certainly true that it's harder to make very high resistances out >>>> of very low resistance materials, and there are lots of low-precision
    applications where 1/f noise is not a serious issue--overvoltage
    protection, for instance.

    However, carbon resistors are seriously nonlinear at high voltages--the >>>> resistance of old style Allen-Bradley carbon comps was allowed to drop >>>> by a quarter at their upper voltage limit.

    Cheers

    Phil Hobbs


    Yes! I learned that the hard way. Decided I was gonna make my own HV
    divider from a string of 22meg CC resistors. I was astonished by the
    change in resistance with voltage. So I made a new scale for the meter.

    In a divider made from a string of identical resistors, the
    nonlinearity cancels. That's why the best dividers are all on the same
    substrate.


    No, I don't think so. The resistors all have a negative voltage
    coefficient and they add in a string.


    But in a divider with 25% matched nonlinearity, you'd have
    1*0.75 / N*0.75 = 1 / N regardless.

    Of course since the nonlinearity is caused by hot filaments beginning to
    form inside the resistive element, one wouldn't expect them to be
    particularly repeatable or time-invariant.

    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@highlandsniptechnology.com on Tue Mar 8 19:47:38 2022
    On a sunny day (Tue, 08 Mar 2022 07:39:29 -0800) it happened jlarkin@highlandsniptechnology.com wrote in <5ute2hlgqblmtf9l7nf3kc8tasr8hooafq@4ax.com>:

    I guess it should be coated or potted or something.

    Ww have a potential customer who wants a 1500 volt power supply
    programmable and stable to 1 PPM. That could get interesting.

    Some sort of shield could prevent corona. But 1500v isn't bad.

    Not just corona, any moisure in the air would screw things up, condensation on your PCB too.
    Done a lot of HV CRT stuff, foucus was for example about 4 kV, done with a large carbon
    wound resistor in the antique sets,,,
    1 ppm is pushing it.
    https://www.wagneronline.com.au/high-voltage-tv-focus-resistors/television-parts/service-repair-parts/1fcr150k-3714/679/pd/

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  • From whit3rd@21:1/5 to jla...@highlandsniptechnology.com on Tue Mar 8 12:56:46 2022
    On Tuesday, March 8, 2022 at 7:39:44 AM UTC-8, jla...@highlandsniptechnology.com wrote:
    On Tue, 8 Mar 2022 03:46:03 -0800 (PST), John Walliker
    <jrwal...@gmail.com> wrote:

    [about carbon resistors]
    The long-term resistance shift doesn't behave that way at high voltages, >because the ones at the top of the string suffer more corona discharge which >can therefore erode them faster. I found this out the hard way.

    I guess it should be coated or potted or something.

    Ww have a potential customer who wants a 1500 volt power supply
    programmable and stable to 1 PPM. That could get interesting.

    Some sort of shield could prevent corona. But 1500v isn't bad.

    It's about the same as focus voltages in old CRT displays; I've replaced
    a lot of focus resistors.

    To prevent corona around a carbon resistor, you might consider getting the resistor sealed in vacuum (glass tube package). At 45 kV auto ignition wiring just had to go to 8mm diameter silicone insulation: the corona in silicone is harder to start than corona in air, so... you build up the insulator to fill the high-field volume entirely.

    Victoreen and Ohmite make vacuum packages : <https://www.ebay.com/itm/123046764521>

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  • From Phil Allison@21:1/5 to John Shithead on Tue Mar 8 13:51:56 2022
    John Shithead wrote:

    ==================

    In a divider made from a string of identical resistors, the
    nonlinearity cancels. That's why the best dividers are all on the same >>> substrate.


    No, I don't think so. The resistors all have a negative voltage
    coefficient and they add in a string.

    Given 10 identical resistors in series, each drops 1/10 of the total voltage.

    Yes.

    ** Game ove.,


    But the resistance at rated voltage is much lower than it is at a
    couple of volts.

    ** You awake ?

    At any applied voltage, all the series Rs have the *same* voltage drop.
    The 10:1 ratio is unchanging it they all have the same deviations.


    ...... Phil

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  • From John Doe@21:1/5 to John S on Wed Mar 9 03:18:17 2022
    John S wrote:

    jlarkin@highlandsniptechnology.com wrote:

    Given 10 identical resistors in series, each drops 1/10 of the total
    voltage.

    Yes. But the resistance at rated voltage is much lower than it is at a
    couple of volts.

    Weird... The current is the same. But as the voltage drops, the total
    remaining resistance decreases too, moving through the divider. Should be simple but... That's why we depend on rules.

    --- SoupGate-Win32 v1.05
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  • From Anthony William Sloman@21:1/5 to Phil Hobbs on Tue Mar 8 19:34:25 2022
    On Wednesday, March 9, 2022 at 3:31:54 AM UTC+11, Phil Hobbs wrote:
    John S wrote:
    On 3/8/2022 4:51 AM, jla...@highlandsniptechnology.com wrote:
    On Mon, 7 Mar 2022 21:18:05 -0600, John S <Sop...@invalid.org> wrote:

    On 3/7/2022 3:27 PM, Phil Hobbs wrote:
    whit3rd wrote:
    On Monday, March 7, 2022 at 11:47:16 AM UTC-8, Phil Hobbs wrote: >>>>>> John Larkin wrote:
    On Mon, 7 Mar 2022 12:35:32 -0500, Phil Hobbs
    <pcdhSpamM...@electrooptical.net> wrote:

    jla...@highlandsniptechnology.com wrote:
    On Mon, 7 Mar 2022 12:03:17 -0500, Phil Hobbs
    <pcdhSpamM...@electrooptical.net> wrote:

    ...gizmo was exhibiting horrific 1/f noise on the spectrum >>>>>>>>>> analyzer. It turned out to be the classic Tektronix 50-ohm 2-W >>>>>>>>>> BNC feedthrough terminator I was using--it was made of cermet. >>>>>>>>>> Switching to metal film dropped the 1/f noise by about two orders >>>>>>>>>> of magnitude IIRC. Not subtle at all.

    It's probably too late, but it would be interesting to measure the >>>>>>> 1/f noise vs current. It might be square law, namely thermal.

    Nah, definitely linear, and definitely 1/f not 1/f**2. A
    constant-rate drift notionally has a spectrum that goes as 1/f**4, >>>>>> and a random-walk drift ('brown noise') goes as 1/f**2.

    Carbon resistors are semi-metals, so they get recombination noise; >>>>
    Not sure what you mean by that, exactly. To get recombination noise you >>>> need minority carriers, no?

    probably the 'cermet' is a similar material.

    Cermets aren't homogeneous--as the name implies, they're ceramic/metal >>>> composites.

    For metal film, though, it's terribly difficult to get a thin and >>>>> long continuous metal path for high resistance,

    Why so? I used to make conducting films of 100 angstroms or so. Atoms >>>> are pretty small, and using sputtering as opposed to directional
    evaporation will make the film follow even rough substrates pretty
    well.

    AND keep it from oxidizing and changing value. > So, carbon (carbon >>>>> film?) still is the solution for high-ohms items.

    It's certainly true that it's harder to make very high resistances out >>>> of very low resistance materials, and there are lots of low-precision >>>> applications where 1/f noise is not a serious issue--overvoltage
    protection, for instance.

    However, carbon resistors are seriously nonlinear at high voltages--the >>>> resistance of old style Allen-Bradley carbon comps was allowed to drop >>>> by a quarter at their upper voltage limit.

    Yes! I learned that the hard way. Decided I was gonna make my own HV
    divider from a string of 22meg CC resistors. I was astonished by the
    change in resistance with voltage. So I made a new scale for the meter. >>
    In a divider made from a string of identical resistors, the
    nonlinearity cancels. That's why the best dividers are all on the same
    substrate.

    No, I don't think so. The resistors all have a negative voltage coefficient and they add in a string.

    But in a divider with 25% matched nonlinearity, you'd have
    1*0.75 / N*0.75 = 1 / N regardless.

    Of course since the nonlinearity is caused by hot filaments beginning to form inside the resistive element, one wouldn't expect them to be particularly repeatable or time-invariant.

    Actually, once a hot channel has formed it can be pretty stable.

    When there is just enough channeling to cause temperate gradients across the current path, these can move the current path around and can give you an unstable resistance. We saw this with NTC thermistors at one place where I worked - when the automated
    test gear tried to dissipate about a milliwatt in the thermistor the resistance - displayed to six significant figures - never showed the same last two digits for any length of time.

    Measuring the resistance on a higher resistance range (with less power dissipated in the thermistor) gave a stable result, but at lower resolution.

    --
    Bill Sloman, Sydney

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  • From Jan Panteltje@21:1/5 to whit3rd@gmail.com on Wed Mar 9 07:45:27 2022
    On a sunny day (Tue, 8 Mar 2022 12:56:46 -0800 (PST)) it happened whit3rd <whit3rd@gmail.com> wrote in <9168331e-8253-4e0a-b06a-a31309a07da3n@googlegroups.com>:

    To prevent corona around a carbon resistor, you might consider getting the >resistor sealed in vacuum (glass tube package). At 45 kV auto ignition >wiring just had to go to 8mm diameter silicone insulation: the corona in >silicone is harder to start than corona in air, so... you build up the >insulator to fill the high-field volume entirely.

    Victoreen and Ohmite make vacuum packages : <https://www.ebay.com/itm/123046764521>

    Very nice
    This morning i ws tinking abiut different physics to measue g=high voltages Icame upo (in my mind that is( with a varant f teh elctrometer

    2 charged plates, on on ground the other on the HV,
    and then the ground one mounted on a piezo like weight sensor
    The attraction between the plates would perhaps be measurable, and no current load

    --------- HV plate

    ---------- GND plate
    ///////// -> weight sensor
    ============= PCB (or whatever

    Accuracy. probably bad


    For my small PMT this setup works fine up to a kV or so:
    http://panteltje.com/pub/PMT_HV_supply_componet_side_img_3180.jpg
    HV resistor divider is on the far left.

    http://panteltje.com/pub/PMT_HV_supply_with_regulator_img_3175.jpg

    is stabilized of course:
    http://www.panteltje.com/pub/PMT_regulated_power_supply_diagram_img_3182.jpg
    filtered PWM rom a PIC micro controls it.
    Been working fine for 11 years now. no idea how accurate, few volt perhaps.
    use a precision opamp?

    I have an other one for a bigger PMT with a lot more voltage:
    http://panteltje.com/panteltje/pic/sc_pic/
    also PIC controlled

    1 ppm ..no but shoud be possible? 1kV 1mV sigh.. ripple.... ?
    LOL

    Do not move near it!

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From jlarkin@highlandsniptechnology.com@21:1/5 to pNaonStpealmtje@yahoo.com on Wed Mar 9 07:26:16 2022
    On Wed, 09 Mar 2022 07:45:27 GMT, Jan Panteltje
    <pNaonStpealmtje@yahoo.com> wrote:

    On a sunny day (Tue, 8 Mar 2022 12:56:46 -0800 (PST)) it happened whit3rd ><whit3rd@gmail.com> wrote in ><9168331e-8253-4e0a-b06a-a31309a07da3n@googlegroups.com>:

    To prevent corona around a carbon resistor, you might consider getting the >>resistor sealed in vacuum (glass tube package). At 45 kV auto ignition >>wiring just had to go to 8mm diameter silicone insulation: the corona in >>silicone is harder to start than corona in air, so... you build up the >>insulator to fill the high-field volume entirely.

    Victoreen and Ohmite make vacuum packages : <https://www.ebay.com/itm/123046764521>

    Very nice
    This morning i ws tinking abiut different physics to measue g=high voltages >Icame upo (in my mind that is( with a varant f teh elctrometer

    2 charged plates, on on ground the other on the HV,
    and then the ground one mounted on a piezo like weight sensor
    The attraction between the plates would perhaps be measurable, and no current load

    --------- HV plate

    ---------- GND plate
    ///////// -> weight sensor
    ============= PCB (or whatever

    Accuracy. probably bad


    For my small PMT this setup works fine up to a kV or so:
    http://panteltje.com/pub/PMT_HV_supply_componet_side_img_3180.jpg
    HV resistor divider is on the far left.

    http://panteltje.com/pub/PMT_HV_supply_with_regulator_img_3175.jpg

    is stabilized of course:
    http://www.panteltje.com/pub/PMT_regulated_power_supply_diagram_img_3182.jpg
    filtered PWM rom a PIC micro controls it.
    Been working fine for 11 years now. no idea how accurate, few volt perhaps. >use a precision opamp?

    I have an other one for a bigger PMT with a lot more voltage:
    http://panteltje.com/panteltje/pic/sc_pic/
    also PIC controlled

    1 ppm ..no but shoud be possible? 1kV 1mV sigh.. ripple.... ?
    LOL

    It might get expensive.


    Do not move near it!





    Nice stuff. MMBD5004S/1SS398TE85LF is a dual 400v diode in SOT23,
    which can shorten a C-W multiplier string.

    https://www.dropbox.com/s/jfx8it5acjwg4je/Z206_CWmult.JPG?raw=1

    https://www.dropbox.com/s/2pgawxq6a0xnqxz/DRQ_11.asc?dl=0



    --

    I yam what I yam - Popeye

    --- SoupGate-Win32 v1.05
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  • From whit3rd@21:1/5 to Jan Panteltje on Wed Mar 9 10:23:22 2022
    On Tuesday, March 8, 2022 at 11:45:48 PM UTC-8, Jan Panteltje wrote:

    This morning i ws tinking abiut different physics to measue g=high voltages Icame upo (in my mind that is( with a varant f teh elctrometer

    2 charged plates, on on ground the other on the HV,
    and then the ground one mounted on a piezo like weight sensor
    The attraction between the plates would perhaps be measurable, and no current load

    --------- HV plate

    ---------- GND plate
    ///////// -> weight sensor
    ============= PCB (or whatever

    Accuracy. probably bad

    That's a variant of traditional electrostatic voltmeter design with a vane
    and plates, which typically is done in rotary fashion with a hairspring for return force... and requires jeweled bearings and level adjustment...
    it's a fiddly nuisance of an instrument, but does pretty well at
    sorting out kilovolts without many picoamps of leakage.
    I suspect the weight sensor will respond to every bit of building shake
    in the wind...


    For my small PMT this setup works fine up to a kV or so: http://panteltje.com/pub/PMT_HV_supply_componet_side_img_3180.jpg

    Yow. So many parts just to replace a single vacuum tube rectifier...

    HV resistor divider is on the far left.

    And then the long string of low-V resistors...

    It'd almost be easier to meter with a field mill (motorized vane
    changing capacitance-to-electrode, and AC amplification
    of the resulting current). An interesting variant would be
    to program a second electrode with some smart PWM
    and balance the pulses from the known-voltage electrode
    and the unknown-voltage electrode.

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Phil Hobbs@21:1/5 to Jan Panteltje on Wed Mar 9 13:35:31 2022
    Jan Panteltje wrote:
    On a sunny day (Tue, 8 Mar 2022 12:56:46 -0800 (PST)) it happened whit3rd <whit3rd@gmail.com> wrote in <9168331e-8253-4e0a-b06a-a31309a07da3n@googlegroups.com>:

    To prevent corona around a carbon resistor, you might consider getting the >> resistor sealed in vacuum (glass tube package). At 45 kV auto ignition
    wiring just had to go to 8mm diameter silicone insulation: the corona in
    silicone is harder to start than corona in air, so... you build up the
    insulator to fill the high-field volume entirely.

    Victoreen and Ohmite make vacuum packages : <https://www.ebay.com/itm/123046764521>

    Very nice
    This morning i ws tinking abiut different physics to measue g=high voltages Icame upo (in my mind that is( with a varant f teh elctrometer

    2 charged plates, on on ground the other on the HV,
    and then the ground one mounted on a piezo like weight sensor
    The attraction between the plates would perhaps be measurable, and no current load

    --------- HV plate

    ---------- GND plate
    ///////// -> weight sensor
    ============= PCB (or whatever

    Accuracy. probably bad


    For my small PMT this setup works fine up to a kV or so:
    http://panteltje.com/pub/PMT_HV_supply_componet_side_img_3180.jpg
    HV resistor divider is on the far left.

    http://panteltje.com/pub/PMT_HV_supply_with_regulator_img_3175.jpg

    is stabilized of course:
    http://www.panteltje.com/pub/PMT_regulated_power_supply_diagram_img_3182.jpg
    filtered PWM rom a PIC micro controls it.
    Been working fine for 11 years now. no idea how accurate, few volt perhaps. use a precision opamp?

    I have an other one for a bigger PMT with a lot more voltage:
    http://panteltje.com/panteltje/pic/sc_pic/
    also PIC controlled

    1 ppm ..no but shoud be possible? 1kV 1mV sigh.. ripple.... ?
    LOL

    Do not move near it!






    The classical method is the vibrating-reed electrometer.

    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 Jan Panteltje@21:1/5 to pcdhSpamMeSenseless@electrooptical. on Wed Mar 9 20:21:52 2022
    On a sunny day (Wed, 9 Mar 2022 13:35:31 -0500) it happened Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net> wrote in <dc533e1c-b0f1-5bca-1a91-f9e9d1fdaa5f@electrooptical.net>:

    Jan Panteltje wrote:
    On a sunny day (Tue, 8 Mar 2022 12:56:46 -0800 (PST)) it happened whit3rd
    <whit3rd@gmail.com> wrote in
    <9168331e-8253-4e0a-b06a-a31309a07da3n@googlegroups.com>:

    To prevent corona around a carbon resistor, you might consider getting the >>> resistor sealed in vacuum (glass tube package). At 45 kV auto ignition >>> wiring just had to go to 8mm diameter silicone insulation: the corona in >>> silicone is harder to start than corona in air, so... you build up the
    insulator to fill the high-field volume entirely.

    Victoreen and Ohmite make vacuum packages : <https://www.ebay.com/itm/123046764521>

    Very nice
    This morning i ws tinking abiut different physics to measue g=high voltages >> Icame upo (in my mind that is( with a varant f teh elctrometer

    2 charged plates, on on ground the other on the HV,
    and then the ground one mounted on a piezo like weight sensor
    The attraction between the plates would perhaps be measurable, and no current load

    --------- HV plate

    ---------- GND plate
    ///////// -> weight sensor
    ============= PCB (or whatever

    Accuracy. probably bad


    For my small PMT this setup works fine up to a kV or so:
    http://panteltje.com/pub/PMT_HV_supply_componet_side_img_3180.jpg
    HV resistor divider is on the far left.

    http://panteltje.com/pub/PMT_HV_supply_with_regulator_img_3175.jpg

    is stabilized of course:
    http://www.panteltje.com/pub/PMT_regulated_power_supply_diagram_img_3182.jpg
    filtered PWM rom a PIC micro controls it.
    Been working fine for 11 years now. no idea how accurate, few volt perhaps. >> use a precision opamp?

    I have an other one for a bigger PMT with a lot more voltage:
    http://panteltje.com/panteltje/pic/sc_pic/
    also PIC controlled

    1 ppm ..no but shoud be possible? 1kV 1mV sigh.. ripple.... ?
    LOL

    Do not move near it!






    The classical method is the vibrating-reed electrometer.

    Thanks, bit of googling found a nice wikipedia article:
    https://en.wikipedia.org/wiki/Electrometer

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From whit3rd@21:1/5 to Phil Hobbs on Wed Mar 9 21:44:03 2022
    On Wednesday, March 9, 2022 at 10:35:47 AM UTC-8, Phil Hobbs wrote:
    Jan Panteltje wrote:

    This morning i ws tinking abiut different physics to measue g=high voltages Icame upo (in my mind that is( with a varant f teh elctrometer

    2 charged plates, on on ground the other on the HV,
    and then the ground one mounted on a piezo like weight sensor
    The attraction between the plates would perhaps be measurable, and no current load

    --------- HV plate

    ---------- GND plate
    ///////// -> weight sensor
    ============= PCB (or whatever

    Accuracy. probably bad


    1 ppm ..no but shoud be possible? 1kV 1mV sigh.. ripple.... ?
    LOL

    Do not move near it!

    The classical method is the vibrating-reed electrometer.

    That's also a 'do not move near it' solution. I scavenged a head unit
    from an old Cary 31 vibrating-reed electrometer, and it's got 10lbs of cast iron to
    keep acoustic input to a minimum; there were selected tubes
    inside to deal with the microphonic feedback, and anyone who
    could afford it (circa 1970) was swapping in new sockets and nuvistor
    tubes, 'cuz microphonics.

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Phil Hobbs@21:1/5 to All on Thu Mar 10 09:23:36 2022
    whit3rd wrote:
    On Wednesday, March 9, 2022 at 10:35:47 AM UTC-8, Phil Hobbs wrote:
    Jan Panteltje wrote:

    This morning i ws tinking abiut different physics to measue g=high voltages >>> Icame upo (in my mind that is( with a varant f teh elctrometer

    2 charged plates, on on ground the other on the HV,
    and then the ground one mounted on a piezo like weight sensor
    The attraction between the plates would perhaps be measurable, and no current load

    --------- HV plate

    ---------- GND plate
    ///////// -> weight sensor
    ============= PCB (or whatever

    Accuracy. probably bad


    1 ppm ..no but shoud be possible? 1kV 1mV sigh.. ripple.... ?
    LOL

    Do not move near it!

    The classical method is the vibrating-reed electrometer.

    That's also a 'do not move near it' solution. I scavenged a head unit
    from an old Cary 31 vibrating-reed electrometer, and it's got 10lbs of cast iron to
    keep acoustic input to a minimum; there were selected tubes
    inside to deal with the microphonic feedback, and anyone who
    could afford it (circa 1970) was swapping in new sockets and nuvistor
    tubes, 'cuz microphonics.


    "Doctor, doctor, it hurts when I go like this!"

    "So don't go like that."

    I used to have a handheld electrometer with an analog dial. It looked a
    bit like an old CdS photographic light meter, and worked fine.

    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)