• Re: HP 8012a

    From bitrex@21:1/5 to bitrex on Tue Apr 26 11:28:55 2022
    On 4/26/2022 11:18 AM, bitrex wrote:
    The HP 8082 uses ECL you can't get no mo, and looks like a PITA to repair:

    <https://youtu.be/09zhUbJl37w>

    Far as I can tell its slower smaller cousin the 8012a is all
    discrete-on-card though, yeah? It looks that way from the service manual
    but I haven't checked every thing.

    <https://www.keysight.com/us/en/assets/9018-03164/user-manuals/9018-03164.pdf>


    A 5ns rise time is still useful for a number of jobs, and I can get a
    dodgy unit for next to nothing locally. I figure if I use it once a year
    it might be worth trying to fix up if it doesn't require exotic parts.

    I don't think I own equipment fast enough to calibrate a refurbed 8082
    anyway, even if it's not the ECL that's the problem

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From jlarkin@highlandsniptechnology.com@21:1/5 to bitrex on Tue Apr 26 08:58:36 2022
    On Tue, 26 Apr 2022 11:28:55 -0400, bitrex <user@example.net> wrote:

    On 4/26/2022 11:18 AM, bitrex wrote:
    The HP 8082 uses ECL you can't get no mo, and looks like a PITA to repair: >>
    <https://youtu.be/09zhUbJl37w>

    Far as I can tell its slower smaller cousin the 8012a is all
    discrete-on-card though, yeah? It looks that way from the service manual
    but I haven't checked every thing.

    <https://www.keysight.com/us/en/assets/9018-03164/user-manuals/9018-03164.pdf>


    A 5ns rise time is still useful for a number of jobs, and I can get a
    dodgy unit for next to nothing locally. I figure if I use it once a year
    it might be worth trying to fix up if it doesn't require exotic parts.

    I don't think I own equipment fast enough to calibrate a refurbed 8082 >anyway, even if it's not the ECL that's the problem

    I'm thinking of doing a pulse generator. There are tons of cheap
    TTL-type ones around, so it would have to be multi-channel and fast.



    --

    Anybody can count to one.

    - Robert Widlar

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From bitrex@21:1/5 to All on Tue Apr 26 11:18:50 2022
    The HP 8082 uses ECL you can't get no mo, and looks like a PITA to repair:

    <https://youtu.be/09zhUbJl37w>

    Far as I can tell its slower smaller cousin the 8012a is all
    discrete-on-card though, yeah? It looks that way from the service manual
    but I haven't checked every thing.

    <https://www.keysight.com/us/en/assets/9018-03164/user-manuals/9018-03164.pdf>

    A 5ns rise time is still useful for a number of jobs, and I can get a
    dodgy unit for next to nothing locally. I figure if I use it once a year
    it might be worth trying to fix up if it doesn't require exotic parts.

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Phil Hobbs@21:1/5 to jlarkin@highlandsniptechnology.com on Tue Apr 26 12:47:15 2022
    jlarkin@highlandsniptechnology.com wrote:
    On Tue, 26 Apr 2022 11:28:55 -0400, bitrex <user@example.net> wrote:

    On 4/26/2022 11:18 AM, bitrex wrote:
    The HP 8082 uses ECL you can't get no mo, and looks like a PITA to repair: >>>
    <https://youtu.be/09zhUbJl37w>

    Far as I can tell its slower smaller cousin the 8012a is all
    discrete-on-card though, yeah? It looks that way from the service manual >>> but I haven't checked every thing.

    <https://www.keysight.com/us/en/assets/9018-03164/user-manuals/9018-03164.pdf>


    A 5ns rise time is still useful for a number of jobs, and I can get a
    dodgy unit for next to nothing locally. I figure if I use it once a year >>> it might be worth trying to fix up if it doesn't require exotic parts.

    I don't think I own equipment fast enough to calibrate a refurbed 8082
    anyway, even if it's not the ECL that's the problem

    I'm thinking of doing a pulse generator. There are tons of cheap
    TTL-type ones around, so it would have to be multi-channel and fast.


    I generally use my P400 for that. Of course it's all synchronous to a
    single T0 channel, so it's completely useless for building the
    asynchronous chain-of-monostable hairballs so beloved of grad students
    of yore. ;)

    I have an HP 8013B, which more or less works but is nothing special.

    Cheers

    Phil Hobbs

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

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

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Phil Hobbs@21:1/5 to bitrex on Tue Apr 26 12:50:16 2022
    bitrex wrote:
    On 4/26/2022 11:18 AM, bitrex wrote:
    The HP 8082 uses ECL you can't get no mo, and looks like a PITA to
    repair:

    <https://youtu.be/09zhUbJl37w>

    Far as I can tell its slower smaller cousin the 8012a is all
    discrete-on-card though, yeah? It looks that way from the service
    manual but I haven't checked every thing.

    <https://www.keysight.com/us/en/assets/9018-03164/user-manuals/9018-03164.pdf>


    A 5ns rise time is still useful for a number of jobs, and I can get a
    dodgy unit for next to nothing locally. I figure if I use it once a
    year it might be worth trying to fix up if it doesn't require exotic
    parts.

    I don't think I own equipment fast enough to calibrate a refurbed 8082 anyway, even if it's not the ECL that's the problem

    Well, there's your problem. You can get a TDS 694C for a couple of
    grand, and I might even kick in a trigger ASIC from my secret stash.

    Cheers

    Phil Hobbs

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

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

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Phil Hobbs@21:1/5 to Phil Hobbs on Tue Apr 26 14:04:52 2022
    Phil Hobbs wrote:
    jlarkin@highlandsniptechnology.com wrote:
    On Tue, 26 Apr 2022 11:28:55 -0400, bitrex <user@example.net> wrote:

    On 4/26/2022 11:18 AM, bitrex wrote:
    The HP 8082 uses ECL you can't get no mo, and looks like a PITA to
    repair:

    <https://youtu.be/09zhUbJl37w>

    Far as I can tell its slower smaller cousin the 8012a is all
    discrete-on-card though, yeah? It looks that way from the service
    manual
    but I haven't checked every thing.

    <https://www.keysight.com/us/en/assets/9018-03164/user-manuals/9018-03164.pdf>



    A 5ns rise time is still useful for a number of jobs, and I can get a
    dodgy unit for next to nothing locally. I figure if I use it once a
    year
    it might be worth trying to fix up if it doesn't require exotic parts.

    I don't think I own equipment fast enough to calibrate a refurbed 8082
    anyway, even if it's not the ECL that's the problem

    I'm thinking of doing a pulse generator. There are tons of cheap
    TTL-type ones around, so it would have to be multi-channel and fast.


    I generally use my P400 for that.  Of course it's all synchronous to a single T0 channel, so it's completely useless for building the
    asynchronous chain-of-monostable hairballs so beloved of grad students
    of yore. ;)

    I should add that one proposal for our snazzy new time stretcher APD
    array chip was to use a 64 x 64 array of linear-mode APDs, with 25 T/Hs
    each, with the track-holds timed using a half-monostable each.

    IOW, as I pointed out, our chip would have had _over a hundred thousand one-shots_ doing the timing. (O tempora! O mores!)

    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 bitrex@21:1/5 to Phil Hobbs on Tue Apr 26 15:10:14 2022
    On 4/26/2022 12:50 PM, Phil Hobbs wrote:
    bitrex wrote:
    On 4/26/2022 11:18 AM, bitrex wrote:
    The HP 8082 uses ECL you can't get no mo, and looks like a PITA to
    repair:

    <https://youtu.be/09zhUbJl37w>

    Far as I can tell its slower smaller cousin the 8012a is all
    discrete-on-card though, yeah? It looks that way from the service
    manual but I haven't checked every thing.

    <https://www.keysight.com/us/en/assets/9018-03164/user-manuals/9018-03164.pdf>


    A 5ns rise time is still useful for a number of jobs, and I can get a
    dodgy unit for next to nothing locally. I figure if I use it once a
    year it might be worth trying to fix up if it doesn't require exotic
    parts.

    I don't think I own equipment fast enough to calibrate a refurbed 8082
    anyway, even if it's not the ECL that's the problem

    Well, there's your problem.  You can get a TDS 694C for a couple of
    grand, and I might even kick in a trigger ASIC from my secret stash.

    Cheers

    Phil Hobbs


    It's a lovely scope but a few other items are going to take priority
    this spring (cleaning) like an Agilent or similar multi-output PSU,
    bench DMM, and LCR meter/impedance analyzer-thing (not quite sure what
    to pick there and am open to suggestions), I've solidly outgrown my
    hand-held DMMs and China-special bench PSUs.

    But a 8012a in unknown condition for $25 sure is tempting.

    My girlfriend picked me up a nice present while she was looking for
    thrift store clothing bargains, a 1987 hardbound HP product lineup guide
    in mint condition, $3.99. Odd thing to find at a thrift store maybe but
    this is the heart of what used to be DEC & Wang etc. country near Rte
    128, maybe someone was cleaning out their closet also.

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From bitrex@21:1/5 to bitrex on Tue Apr 26 15:19:18 2022
    On 4/26/2022 3:16 PM, bitrex wrote:
    On 4/26/2022 12:50 PM, Phil Hobbs wrote:
    bitrex wrote:
    On 4/26/2022 11:18 AM, bitrex wrote:
    The HP 8082 uses ECL you can't get no mo, and looks like a PITA to
    repair:

    <https://youtu.be/09zhUbJl37w>

    Far as I can tell its slower smaller cousin the 8012a is all
    discrete-on-card though, yeah? It looks that way from the service
    manual but I haven't checked every thing.

    <https://www.keysight.com/us/en/assets/9018-03164/user-manuals/9018-03164.pdf>


    A 5ns rise time is still useful for a number of jobs, and I can get
    a dodgy unit for next to nothing locally. I figure if I use it once
    a year it might be worth trying to fix up if it doesn't require
    exotic parts.

    I don't think I own equipment fast enough to calibrate a refurbed
    8082 anyway, even if it's not the ECL that's the problem

    Well, there's your problem.  You can get a TDS 694C for a couple of
    grand, and I might even kick in a trigger ASIC from my secret stash.

    Cheers

    Phil Hobbs


    The service manual seems to say you need a 100 MHz pulse generator like
    the 8007a to calibrate an 8082a. Seems like a Dear Liza kind of situation

    Er, to calibrate the 8012a, rather

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From bitrex@21:1/5 to Phil Hobbs on Tue Apr 26 15:16:37 2022
    On 4/26/2022 12:50 PM, Phil Hobbs wrote:
    bitrex wrote:
    On 4/26/2022 11:18 AM, bitrex wrote:
    The HP 8082 uses ECL you can't get no mo, and looks like a PITA to
    repair:

    <https://youtu.be/09zhUbJl37w>

    Far as I can tell its slower smaller cousin the 8012a is all
    discrete-on-card though, yeah? It looks that way from the service
    manual but I haven't checked every thing.

    <https://www.keysight.com/us/en/assets/9018-03164/user-manuals/9018-03164.pdf>


    A 5ns rise time is still useful for a number of jobs, and I can get a
    dodgy unit for next to nothing locally. I figure if I use it once a
    year it might be worth trying to fix up if it doesn't require exotic
    parts.

    I don't think I own equipment fast enough to calibrate a refurbed 8082
    anyway, even if it's not the ECL that's the problem

    Well, there's your problem.  You can get a TDS 694C for a couple of
    grand, and I might even kick in a trigger ASIC from my secret stash.

    Cheers

    Phil Hobbs


    The service manual seems to say you need a 100 MHz pulse generator like
    the 8007a to calibrate an 8082a. Seems like a Dear Liza kind of situation

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From jlarkin@highlandsniptechnology.com@21:1/5 to pcdhSpamMeSenseless@electrooptical. on Tue Apr 26 19:15:15 2022
    On Tue, 26 Apr 2022 12:47:15 -0400, Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net> wrote:

    jlarkin@highlandsniptechnology.com wrote:
    On Tue, 26 Apr 2022 11:28:55 -0400, bitrex <user@example.net> wrote:

    On 4/26/2022 11:18 AM, bitrex wrote:
    The HP 8082 uses ECL you can't get no mo, and looks like a PITA to repair: >>>>
    <https://youtu.be/09zhUbJl37w>

    Far as I can tell its slower smaller cousin the 8012a is all
    discrete-on-card though, yeah? It looks that way from the service manual >>>> but I haven't checked every thing.

    <https://www.keysight.com/us/en/assets/9018-03164/user-manuals/9018-03164.pdf>


    A 5ns rise time is still useful for a number of jobs, and I can get a
    dodgy unit for next to nothing locally. I figure if I use it once a year >>>> it might be worth trying to fix up if it doesn't require exotic parts.

    I don't think I own equipment fast enough to calibrate a refurbed 8082
    anyway, even if it's not the ECL that's the problem

    I'm thinking of doing a pulse generator. There are tons of cheap
    TTL-type ones around, so it would have to be multi-channel and fast.


    I generally use my P400 for that. Of course it's all synchronous to a
    single T0 channel, so it's completely useless for building the
    asynchronous chain-of-monostable hairballs so beloved of grad students
    of yore. ;)


    Reminds me, I should send you a P500 when we have some to spare. It
    has the 25 v p-p GaN output stage, super-clean.



    --

    Anybody can count to one.

    - Robert Widlar

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Don Y@21:1/5 to bitrex on Tue Apr 26 18:49:11 2022
    On 4/26/2022 8:28 AM, bitrex wrote:
    On 4/26/2022 11:18 AM, bitrex wrote:
    The HP 8082 uses ECL you can't get no mo, and looks like a PITA to repair: >>
    <https://youtu.be/09zhUbJl37w>

    Far as I can tell its slower smaller cousin the 8012a is all discrete-on-card
    though, yeah? It looks that way from the service manual but I haven't checked
    every thing.

    <https://www.keysight.com/us/en/assets/9018-03164/user-manuals/9018-03164.pdf>

    A 5ns rise time is still useful for a number of jobs, and I can get a dodgy >> unit for next to nothing locally. I figure if I use it once a year it might >> be worth trying to fix up if it doesn't require exotic parts.

    You can often pick up used kit from local tech firms, universities (excellent source of kit as they often dump everything they purchased for a GRANT project when the grant is over), etc. Some firms just contract disposal of their kit to a firm; others sell at auction (which may or may not be "public"). Knowing folks at these places is a great way to get the inside track...

    I don't think I own equipment fast enough to calibrate a refurbed 8082 anyway,
    even if it's not the ECL that's the problem

    Yeah, I rescued an HP 3458A many years ago. After the initial "pride of rescueship" (v "ownership") wore off, I realized it was just an oversized
    *4* digit DVM given that I never needed more accuracy/precision than that!
    And, surely wasn't going to PAY to have it calibrated to 8+ digits!

    (here, bench space is far more precious than quality of kit!)

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Anthony William Sloman@21:1/5 to jla...@highlandsniptechnology.com on Tue Apr 26 19:20:30 2022
    On Wednesday, April 27, 2022 at 1:58:48 AM UTC+10, jla...@highlandsniptechnology.com wrote:
    On Tue, 26 Apr 2022 11:28:55 -0400, bitrex <us...@example.net> wrote:

    On 4/26/2022 11:18 AM, bitrex wrote:
    The HP 8082 uses ECL you can't get no mo, and looks like a PITA to repair:

    <https://youtu.be/09zhUbJl37w>

    Far as I can tell its slower smaller cousin the 8012a is all
    discrete-on-card though, yeah? It looks that way from the service manual >> but I haven't checked every thing.

    <https://www.keysight.com/us/en/assets/9018-03164/user-manuals/9018-03164.pdf>


    A 5ns rise time is still useful for a number of jobs, and I can get a
    dodgy unit for next to nothing locally. I figure if I use it once a year >> it might be worth trying to fix up if it doesn't require exotic parts.

    I don't think I own equipment fast enough to calibrate a refurbed 8082 >anyway, even if it's not the ECL that's the problem
    I'm thinking of doing a pulse generator. There are tons of cheap
    TTL-type ones around, so it would have to be multi-channel and fast.

    Do it with ECLinPs which is still around, and a whole lot faster than the old ECL which has now gone obsolescent.

    https://www.onsemi.com/pdf/datasheet/mc100ep195b-d.pdf

    is a nice part - the delay is programable up to 10nsec in roughly 10psec increments, but the actual delay is temperature dependent.

    My solution to the problem (back around 1998) was to measure all the delays every ten minutes of so - I'd worked out a scheme for doing it in a few milliseconds - but the project got binned before we could turn it into working hardware. Not because it
    wouldn't have worked, but because the customer got his grant money cut off.

    Regular applications would probably have to ping-pong between two output stages and recalibrate one while the other one was serving the customer, but an ingenious designer like John Larkin should be able to come up with something even better.

    --
    Bill Sloman, Sydney

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From bitrex@21:1/5 to Don Y on Tue Apr 26 22:59:24 2022
    On 4/26/2022 9:49 PM, Don Y wrote:
    On 4/26/2022 8:28 AM, bitrex wrote:
    On 4/26/2022 11:18 AM, bitrex wrote:
    The HP 8082 uses ECL you can't get no mo, and looks like a PITA to
    repair:

    <https://youtu.be/09zhUbJl37w>

    Far as I can tell its slower smaller cousin the 8012a is all
    discrete-on-card though, yeah? It looks that way from the service
    manual but I haven't checked every thing.

    <https://www.keysight.com/us/en/assets/9018-03164/user-manuals/9018-03164.pdf>


    A 5ns rise time is still useful for a number of jobs, and I can get a
    dodgy unit for next to nothing locally. I figure if I use it once a
    year it might be worth trying to fix up if it doesn't require exotic
    parts.

    You can often pick up used kit from local tech firms, universities
    (excellent
    source of kit as they often dump everything they purchased for a GRANT project
    when the grant is over), etc.  Some firms just contract disposal of
    their kit
    to a firm; others sell at auction (which may or may not be "public").
    Knowing
    folks at these places is a great way to get the inside track...


    There is a re-seller like that near me with several dozen "tested"
    3478As bench DMMs available for $150 per (better test the AC section
    though as it uses an unobtaninum part) and another place will calibrate
    it for $50.

    <https://youtu.be/9v6OksEFqpA>

    I think I'll pick up a couple I used them in college & they're still
    nice meters.


    I don't think I own equipment fast enough to calibrate a refurbed 8082
    anyway, even if it's not the ECL that's the problem

    Yeah, I rescued an HP 3458A many years ago.  After the initial "pride of rescueship" (v "ownership") wore off, I realized it was just an oversized
    *4* digit DVM given that I never needed more accuracy/precision than that! And, surely wasn't going to PAY to have it calibrated to 8+ digits!

    (here, bench space is far more precious than quality of kit!)

    Going off BW * tr = 0.34 as the fastest edge a DSO can even assign a
    sample to, much less measure the rise time of accurately, I figure a 100
    MHz scope is too sluggish to calibrate a 5ns pulser on its fastest
    setting. /shrug

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Don Y@21:1/5 to bitrex on Tue Apr 26 20:44:13 2022
    On 4/26/2022 7:59 PM, bitrex wrote:
    You can often pick up used kit from local tech firms, universities (excellent
    source of kit as they often dump everything they purchased for a GRANT project
    when the grant is over), etc. Some firms just contract disposal of their kit
    to a firm; others sell at auction (which may or may not be "public"). Knowing
    folks at these places is a great way to get the inside track...

    There is a re-seller like that near me with several dozen "tested" 3478As bench
    DMMs available for $150 per (better test the AC section though as it uses an unobtaninum part) and another place will calibrate it for $50.

    Resellers increase the price but usually don't add much "value". You want
    to find the guy *he* buys from (usually someone at ABC Tech Corporation).

    I think I'll pick up a couple I used them in college & they're still nice meters.

    I don't think I own equipment fast enough to calibrate a refurbed 8082
    anyway, even if it's not the ECL that's the problem

    Yeah, I rescued an HP 3458A many years ago. After the initial "pride of
    rescueship" (v "ownership") wore off, I realized it was just an oversized
    *4* digit DVM given that I never needed more accuracy/precision than that! >> And, surely wasn't going to PAY to have it calibrated to 8+ digits!

    (here, bench space is far more precious than quality of kit!)

    Going off BW * tr = 0.34 as the fastest edge a DSO can even assign a sample to,
    much less measure the rise time of accurately, I figure a 100 MHz scope is too
    sluggish to calibrate a 5ns pulser on its fastest setting. /shrug

    Most of the products I've designed have intentionally NOT required close tolerances on anything. That adds cost -- in parts or calibration labor.
    So, we design products that rely on other means to make sense of their observations (ratiometric or other "self calibration" tricks).

    [It's not uncommon to have manufacturing tolerances of -60%, +300%. Easy to accommodate if you are smart about it.]

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Anthony William Sloman@21:1/5 to Don Y on Tue Apr 26 21:53:53 2022
    On Wednesday, April 27, 2022 at 1:44:33 PM UTC+10, Don Y wrote:
    On 4/26/2022 7:59 PM, bitrex wrote:
    You can often pick up used kit from local tech firms, universities (excellent
    source of kit as they often dump everything they purchased for a GRANT project
    when the grant is over), etc. Some firms just contract disposal of their kit
    to a firm; others sell at auction (which may or may not be "public"). Knowing
    folks at these places is a great way to get the inside track...

    There is a re-seller like that near me with several dozen "tested" 3478As bench
    DMMs available for $150 per (better test the AC section though as it uses an
    unobtaninum part) and another place will calibrate it for $50.
    Resellers increase the price but usually don't add much "value". You want
    to find the guy *he* buys from (usually someone at ABC Tech Corporation).
    I think I'll pick up a couple I used them in college & they're still nice meters.

    I don't think I own equipment fast enough to calibrate a refurbed 8082 >>> anyway, even if it's not the ECL that's the problem

    Yeah, I rescued an HP 3458A many years ago. After the initial "pride of
    rescueship" (v "ownership") wore off, I realized it was just an oversized >> *4* digit DVM given that I never needed more accuracy/precision than that! >> And, surely wasn't going to PAY to have it calibrated to 8+ digits!

    (here, bench space is far more precious than quality of kit!)

    Going off BW * tr = 0.34 as the fastest edge a DSO can even assign a sample to,
    much less measure the rise time of accurately, I figure a 100 MHz scope is too
    sluggish to calibrate a 5ns pulser on its fastest setting. /shrug
    Most of the products I've designed have intentionally NOT required close tolerances on anything. That adds cost -- in parts or calibration labor.
    So, we design products that rely on other means to make sense of their observations (ratiometric or other "self calibration" tricks).

    [It's not uncommon to have manufacturing tolerances of -60%, +300%. Easy to accommodate if you are smart about it.]

    There are precise parts around, and some that can be made very precise with nothing more than careful assembly.

    The Thompson-Lampard calculable capacitor is the poster-child for that approach.

    https://aapt.scitation.org/doi/10.1119/1.19203

    It's usually used with a laser interferometer to get the length exactly right.

    At a more mundane level, a ratio transformer can be wound by hand to give 0.1ppm ratio accuracy. A 1:1 bifilar wound inductive divider can be accurate to one part per billion.

    I've not seen anybody use Litz wire to make a ratio transformer, which would probably work better than the merely twisted bundles of wire use in regular ration transformers.

    It's never all that easy to get rid of all the potential errors, and it's lot safer to just buy precise parts when you can.

    --
    Bill Sloman, Sydney

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Chris Jones@21:1/5 to bitrex on Wed Apr 27 14:35:51 2022
    On 27/04/2022 12:59, bitrex wrote:
    On 4/26/2022 9:49 PM, Don Y wrote:
    On 4/26/2022 8:28 AM, bitrex wrote:
    On 4/26/2022 11:18 AM, bitrex wrote:
    The HP 8082 uses ECL you can't get no mo, and looks like a PITA to
    repair:

    <https://youtu.be/09zhUbJl37w>

    Far as I can tell its slower smaller cousin the 8012a is all
    discrete-on-card though, yeah? It looks that way from the service
    manual but I haven't checked every thing.

    <https://www.keysight.com/us/en/assets/9018-03164/user-manuals/9018-03164.pdf>


    A 5ns rise time is still useful for a number of jobs, and I can get
    a dodgy unit for next to nothing locally. I figure if I use it once
    a year it might be worth trying to fix up if it doesn't require
    exotic parts.

    You can often pick up used kit from local tech firms, universities
    (excellent
    source of kit as they often dump everything they purchased for a GRANT
    project
    when the grant is over), etc.  Some firms just contract disposal of
    their kit
    to a firm; others sell at auction (which may or may not be "public").

    Around here it goes in a dumpster. Recently found a working TEK468 in
    nearly perfect condition, with probes and everything. I don't see a lot
    of it because it gets covered by the next layer, or it gets rained on,
    or smashed by the next thing chucked in, or I just don't have the space.

    Knowing
    folks at these places is a great way to get the inside track...


    There is a re-seller like that near me with several dozen "tested"
    3478As bench DMMs available for $150 per (better test the AC section
    though as it uses an unobtaninum part) and another place will calibrate
    it for $50.

    <https://youtu.be/9v6OksEFqpA>

    I think I'll pick up a couple I used them in college & they're still
    nice meters.

    If you want to back up the SRAM calibration constants from a HP3478A
    before the battery goes flat and loses it, there is now a project to
    make a USB-GPIB interface with an Arduino:

    https://github.com/Twilight-Logic/AR488

    PCB to go with it:
    https://oshpark.com/shared_projects/yfUOmUzA

    Arduino clone that fits the PCB: https://core-electronics.com.au/pro-micro-5v-16mhz.html

    Needed drivers from the sparkfun website to suit that board:

    https://learn.sparkfun.com/tutorials/pro-micro--fio-v3-hookup-guide/installing-windows

    I don't normally use arduino stuff so that took a while to get working,
    and only recent versions of the arduino IDE would compile it.

    This software makes it easy to backup the SRAM contents using the AR488
    GPIB adapter, and it allows you to tweak the offsets and gains and
    re-generate a good checksum too, though I haven't tried it yet:

    https://mesterhome.com/gpibsw/hp3478a/index.html

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Don Y@21:1/5 to Chris Jones on Tue Apr 26 22:18:52 2022
    On 4/26/2022 9:35 PM, Chris Jones wrote:
    On 27/04/2022 12:59, bitrex wrote:
    On 4/26/2022 9:49 PM, Don Y wrote:
    On 4/26/2022 8:28 AM, bitrex wrote:
    On 4/26/2022 11:18 AM, bitrex wrote:
    The HP 8082 uses ECL you can't get no mo, and looks like a PITA to repair:

    <https://youtu.be/09zhUbJl37w>

    Far as I can tell its slower smaller cousin the 8012a is all
    discrete-on-card though, yeah? It looks that way from the service manual >>>>> but I haven't checked every thing.

    <https://www.keysight.com/us/en/assets/9018-03164/user-manuals/9018-03164.pdf>


    A 5ns rise time is still useful for a number of jobs, and I can get a >>>>> dodgy unit for next to nothing locally. I figure if I use it once a year >>>>> it might be worth trying to fix up if it doesn't require exotic parts. >>>
    You can often pick up used kit from local tech firms, universities (excellent
    source of kit as they often dump everything they purchased for a GRANT project
    when the grant is over), etc. Some firms just contract disposal of their kit
    to a firm; others sell at auction (which may or may not be "public").

    Around here it goes in a dumpster. Recently found a working TEK468 in nearly perfect condition, with probes and everything. I don't see a lot of it because
    it gets covered by the next layer, or it gets rained on, or smashed by the next
    thing chucked in, or I just don't have the space.

    This -------------------------^^^^^^^^^^^^^^^^^^^^^ It's amazing how easily you can accumulate "stuph"! Then, look back and say "Why the hell do I
    HAVE all of these things?? When was the last time I actually *used* them??!"

    Here, it is considered hazardous waste (eWaste). A private individual can likely get away with tossing the occasional piece into their "weekly trash pickup". The "trash-man" watches the contents of your barrel as it is
    emptied into the truck (hydraulic lift). So, you hope he's not a stickler
    *or* hope he can't recognize certain bits of kit. CRTs are almost impossible to sneak past them!

    But, businesses face more scrutiny -- and have larger volumes involved (and usually contract out their trash removal so the trash guy would potentially be screwed if found "misbehaving")

    If you can claim them to be reused/refurbished/repurposed/recycled, then
    there are many nonprofit groups who will accept them as donations (i.e.,
    tax write-off to donor) and dispose of them more suitably (refurbish
    and find them new homes or dismantle and recycle for component parts).
    Groups, here, probably process ~5000+ PCs annually from such corporate
    donors. (I triage ~2000 units in a normal year)

    There is often some risk with this approach as the donor may want to
    slip some "hard to recycle" items in with the "donation" (I've had
    to deal with medical devices using "odd"/dubious solutions, narcotics
    like morphine sulphate, hypodermics, *used* suture kits, etc.).

    Universities tend to opt for auctions to dispose of their "trash" (a
    friend is fond of pointing out "You're PAYING for their TRASH!!!").
    The same sort of issues can apply (I once was interested in a very nice
    "lot" -- only to notice a 10 pound jar of mercury buried in the pile: "Responsibility for proper disposal of the items lies entirely with the purchaser")

    OTOH, you can often find NIB items that simply didn't get unpacked or
    used, as intended, before being discarded. (most of my larger UPSs
    came to me via this route... 2KVA-5KVA with functional batteries!)

    Knowing
    folks at these places is a great way to get the inside track...

    There is a re-seller like that near me with several dozen "tested" 3478As
    bench DMMs available for $150 per (better test the AC section though as it >> uses an unobtaninum part) and another place will calibrate it for $50.

    <https://youtu.be/9v6OksEFqpA>

    I think I'll pick up a couple I used them in college & they're still nice
    meters.

    If you want to back up the SRAM calibration constants from a HP3478A before the
    battery goes flat and loses it, there is now a project to make a USB-GPIB interface with an Arduino:

    If it's an integrated "BBSRAM module", you can likely just remove it and
    read it as a ROM (I have had to do this on many old bits of Sun kit).

    https://github.com/Twilight-Logic/AR488

    PCB to go with it:
    https://oshpark.com/shared_projects/yfUOmUzA

    Arduino clone that fits the PCB: https://core-electronics.com.au/pro-micro-5v-16mhz.html

    Needed drivers from the sparkfun website to suit that board:

    https://learn.sparkfun.com/tutorials/pro-micro--fio-v3-hookup-guide/installing-windows

    I don't normally use arduino stuff so that took a while to get working, and only recent versions of the arduino IDE would compile it.

    This software makes it easy to backup the SRAM contents using the AR488 GPIB adapter, and it allows you to tweak the offsets and gains and re-generate a good checksum too, though I haven't tried it yet:

    https://mesterhome.com/gpibsw/hp3478a/index.html

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Phil Hobbs@21:1/5 to Don Y on Wed Apr 27 04:15:50 2022
    Don Y wrote:
    On 4/26/2022 7:59 PM, bitrex wrote:
    You can often pick up used kit from local tech firms, universities
    (excellent
    source of kit as they often dump everything they purchased for a
    GRANT project
    when the grant is over), etc.  Some firms just contract disposal of
    their kit
    to a firm; others sell at auction (which may or may not be "public").
    Knowing
    folks at these places is a great way to get the inside track...

    There is a re-seller like that near me with several dozen "tested"
    3478As bench DMMs available for $150 per (better test the AC section
    though as it uses an unobtaninum part) and another place will
    calibrate it for $50.

    Resellers increase the price but usually don't add much "value".  You want to find the guy *he* buys from (usually someone at ABC Tech Corporation).

    I think I'll pick up a couple I used them in college & they're still
    nice meters.

    I don't think I own equipment fast enough to calibrate a refurbed
    8082 anyway, even if it's not the ECL that's the problem

    Yeah, I rescued an HP 3458A many years ago.  After the initial "pride of >>> rescueship" (v "ownership") wore off, I realized it was just an
    oversized
    *4* digit DVM given that I never needed more accuracy/precision than
    that!
    And, surely wasn't going to PAY to have it calibrated to 8+ digits!

    (here, bench space is far more precious than quality of kit!)

    Going off BW * tr = 0.34 as the fastest edge a DSO can even assign a
    sample to, much less measure the rise time of accurately, I figure a
    100 MHz scope is too sluggish to calibrate a 5ns pulser on its fastest
    setting. /shrug

    Most of the products I've designed have intentionally NOT required close tolerances on anything.  That adds cost -- in parts or calibration labor. So, we design products that rely on other means to make sense of their observations (ratiometric or other "self calibration" tricks).

    [It's not uncommon to have manufacturing tolerances of -60%, +300%.
    Easy to
    accommodate if you are smart about it.]

    A pity you didn't just replace NIST. ;)

    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 Don Y@21:1/5 to Phil Hobbs on Wed Apr 27 02:50:36 2022
    On 4/27/2022 1:15 AM, Phil Hobbs wrote:
    Don Y wrote:

    [It's not uncommon to have manufacturing tolerances of -60%, +300%. Easy to >> accommodate if you are smart about it.]

    A pity you didn't just replace NIST. ;)

    Lots of things don't need to be qualified in "engineering units".

    How do you test that the *hammer* you are building, today, is as good
    as the hammers you've built in the past? Or, a screwdriver? Just
    how "durable" should the finish on a tape rule be?

    [who, besides the manufacturer, would know how to interpret those data?
    What units? How to evaluate relative to other vendors' products?]

    How do you verify that the (pharmaceutical) tablet that you produced NOW
    is as good as the one you produced 5 milliseconds earlier?

    [Does the consumer care if a particular batch of tablets have a friability
    of 1.2%? Or, variations of hardness on the order of 2KP? Or, a dissolution time that varies by 4% in a particular sample of tablets?]

    In many cases, you rely on some other (external) determinant of "acceptable quality" and the goal is just to ensure repeatability of process. E.g.,
    those "good" tablets were produced with 4.5 bogounits of force exerted during the compression phase; make sure all of them experience a similar force. Or,
    a sample of those hammers struck the test anvil 1825 times, on average, before the handle snapped; the competitor's hammers broke at 1615 strikes, on average. Etc.

    Statistical Process Control becomes more important than traditional control theory (use a conventional control loop and wrap SPC around that)

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Anthony William Sloman@21:1/5 to Don Y on Wed Apr 27 06:47:50 2022
    On Wednesday, April 27, 2022 at 7:50:56 PM UTC+10, Don Y wrote:
    On 4/27/2022 1:15 AM, Phil Hobbs wrote:
    Don Y wrote:

    [It's not uncommon to have manufacturing tolerances of -60%, +300%. Easy to
    accommodate if you are smart about it.]

    A pity you didn't just replace NIST. ;)
    Lots of things don't need to be qualified in "engineering units".

    How do you test that the *hammer* you are building, today, is as good
    as the hammers you've built in the past? Or, a screwdriver? Just
    how "durable" should the finish on a tape rule be?

    [who, besides the manufacturer, would know how to interpret those data?
    What units? How to evaluate relative to other vendors' products?]

    How do you verify that the (pharmaceutical) tablet that you produced NOW
    is as good as the one you produced 5 milliseconds earlier?

    If it contains the same amount of the specific chemical compound that constitutes it active ingredient, it is pretty much certain to be just as good.

    [Does the consumer care if a particular batch of tablets have a friability
    of 1.2%? Or, variations of hardness on the order of 2KP? Or, a dissolution time that varies by 4% in a particular sample of tablets?]

    As long as the active dose gets into their body, they couldn't care less.

    In many cases, you rely on some other (external) determinant of "acceptable quality" and the goal is just to ensure repeatability of process. E.g.,
    those "good" tablets were produced with 4.5 bogounits of force exerted during the compression phase; make sure all of them experience a similar force.

    Nobody could care less how tightly squeezed the tablets were as long as they dissolved in the right bit of the digestive system.

    Or, a sample of those hammers struck the test anvil 1825 times, on average, before
    the handle snapped; the competitor's hammers broke at 1615 strikes, on average.

    The time it takes to break the handle of a hammer is worth worrying about, but it shouldn't ever break at all.

    Statistical Process Control becomes more important than traditional control theory (use a conventional control loop and wrap SPC around that).

    No amount of statistical process control can compensate fro somebody who won't think about what they are measuring, and why it matters.
    You just scored a massive fail on that.

    --
    Bill Sloman, Sydney

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From jlarkin@highlandsniptechnology.com@21:1/5 to pcdhSpamMeSenseless@electrooptical. on Wed Apr 27 07:27:23 2022
    On Wed, 27 Apr 2022 04:15:50 -0400, Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net> wrote:

    Don Y wrote:
    On 4/26/2022 7:59 PM, bitrex wrote:
    You can often pick up used kit from local tech firms, universities
    (excellent
    source of kit as they often dump everything they purchased for a
    GRANT project
    when the grant is over), etc. Some firms just contract disposal of
    their kit
    to a firm; others sell at auction (which may or may not be "public").
    Knowing
    folks at these places is a great way to get the inside track...

    There is a re-seller like that near me with several dozen "tested"
    3478As bench DMMs available for $150 per (better test the AC section
    though as it uses an unobtaninum part) and another place will
    calibrate it for $50.

    Resellers increase the price but usually don't add much "value". You want >> to find the guy *he* buys from (usually someone at ABC Tech Corporation).

    I think I'll pick up a couple I used them in college & they're still
    nice meters.

    I don't think I own equipment fast enough to calibrate a refurbed
    8082 anyway, even if it's not the ECL that's the problem

    Yeah, I rescued an HP 3458A many years ago. After the initial "pride of >>>> rescueship" (v "ownership") wore off, I realized it was just an
    oversized
    *4* digit DVM given that I never needed more accuracy/precision than
    that!
    And, surely wasn't going to PAY to have it calibrated to 8+ digits!

    (here, bench space is far more precious than quality of kit!)

    Going off BW * tr = 0.34 as the fastest edge a DSO can even assign a
    sample to, much less measure the rise time of accurately, I figure a
    100 MHz scope is too sluggish to calibrate a 5ns pulser on its fastest
    setting. /shrug

    Most of the products I've designed have intentionally NOT required close
    tolerances on anything. That adds cost -- in parts or calibration labor.
    So, we design products that rely on other means to make sense of their
    observations (ratiometric or other "self calibration" tricks).

    [It's not uncommon to have manufacturing tolerances of -60%, +300%.
    Easy to
    accommodate if you are smart about it.]

    A pity you didn't just replace NIST. ;)

    Cheers

    Phil Hobbs

    Another NOLA story: we'd send drawings out to machine shops and get
    stuff that didn't fit. They responded that we should send them
    drawings with tolerances, and circle some in red with the note HOLD.

    Life's too short to worry about the small stuff, I guess.

    The Silicon Bayou and similar plans never seemed to work out. That's
    one reason why I left.





    --

    Anybody can count to one.

    - Robert Widlar

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From jlarkin@highlandsniptechnology.com@21:1/5 to bitrex on Wed Apr 27 07:31:40 2022
    On Tue, 26 Apr 2022 22:59:24 -0400, bitrex <user@example.net> wrote:

    On 4/26/2022 9:49 PM, Don Y wrote:
    On 4/26/2022 8:28 AM, bitrex wrote:
    On 4/26/2022 11:18 AM, bitrex wrote:
    The HP 8082 uses ECL you can't get no mo, and looks like a PITA to
    repair:

    <https://youtu.be/09zhUbJl37w>

    Far as I can tell its slower smaller cousin the 8012a is all
    discrete-on-card though, yeah? It looks that way from the service
    manual but I haven't checked every thing.

    <https://www.keysight.com/us/en/assets/9018-03164/user-manuals/9018-03164.pdf>


    A 5ns rise time is still useful for a number of jobs, and I can get a
    dodgy unit for next to nothing locally. I figure if I use it once a
    year it might be worth trying to fix up if it doesn't require exotic
    parts.

    You can often pick up used kit from local tech firms, universities
    (excellent
    source of kit as they often dump everything they purchased for a GRANT
    project
    when the grant is over), etc. Some firms just contract disposal of
    their kit
    to a firm; others sell at auction (which may or may not be "public").
    Knowing
    folks at these places is a great way to get the inside track...


    There is a re-seller like that near me with several dozen "tested"
    3478As bench DMMs available for $150 per (better test the AC section
    though as it uses an unobtaninum part) and another place will calibrate
    it for $50.

    <https://youtu.be/9v6OksEFqpA>

    I think I'll pick up a couple I used them in college & they're still
    nice meters.


    I don't think I own equipment fast enough to calibrate a refurbed 8082
    anyway, even if it's not the ECL that's the problem

    Yeah, I rescued an HP 3458A many years ago. After the initial "pride of
    rescueship" (v "ownership") wore off, I realized it was just an oversized
    *4* digit DVM given that I never needed more accuracy/precision than that! >> And, surely wasn't going to PAY to have it calibrated to 8+ digits!

    (here, bench space is far more precious than quality of kit!)

    Going off BW * tr = 0.34 as the fastest edge a DSO can even assign a
    sample to, much less measure the rise time of accurately, I figure a 100
    MHz scope is too sluggish to calibrate a 5ns pulser on its fastest
    setting. /shrug

    The 0.34 is a relic of the past, when scopes were gaussian. Most
    scopes these days are peaked to meet their bandwidth claim, so even if
    they do make their -3 dB spec they ring like bells.

    If a scope is an honest 100 MHz, with a 3.5 ns Trr, it should be OK to
    measure a 5 ns edge; just math it.

    Or get an old Tek 20 GHz sampler.



    --

    Anybody can count to one.

    - Robert Widlar

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From bitrex@21:1/5 to bitrex on Wed Apr 27 13:21:45 2022
    On 4/27/2022 1:17 PM, bitrex wrote:
    On 4/27/2022 10:31 AM, jlarkin@highlandsniptechnology.com wrote:
    On Tue, 26 Apr 2022 22:59:24 -0400, bitrex <user@example.net> wrote:

    On 4/26/2022 9:49 PM, Don Y wrote:
    On 4/26/2022 8:28 AM, bitrex wrote:
    On 4/26/2022 11:18 AM, bitrex wrote:
    The HP 8082 uses ECL you can't get no mo, and looks like a PITA to >>>>>> repair:

    <https://youtu.be/09zhUbJl37w>

    Far as I can tell its slower smaller cousin the 8012a is all
    discrete-on-card though, yeah? It looks that way from the service
    manual but I haven't checked every thing.

    <https://www.keysight.com/us/en/assets/9018-03164/user-manuals/9018-03164.pdf>



    A 5ns rise time is still useful for a number of jobs, and I can get a >>>>>> dodgy unit for next to nothing locally. I figure if I use it once a >>>>>> year it might be worth trying to fix up if it doesn't require exotic >>>>>> parts.

    You can often pick up used kit from local tech firms, universities
    (excellent
    source of kit as they often dump everything they purchased for a GRANT >>>> project
    when the grant is over), etc.  Some firms just contract disposal of
    their kit
    to a firm; others sell at auction (which may or may not be "public").
    Knowing
    folks at these places is a great way to get the inside track...


    There is a re-seller like that near me with several dozen "tested"
    3478As bench DMMs available for $150 per (better test the AC section
    though as it uses an unobtaninum part) and another place will calibrate
    it for $50.

    <https://youtu.be/9v6OksEFqpA>

    I think I'll pick up a couple I used them in college & they're still
    nice meters.


    I don't think I own equipment fast enough to calibrate a refurbed 8082 >>>>> anyway, even if it's not the ECL that's the problem

    Yeah, I rescued an HP 3458A many years ago.  After the initial
    "pride of
    rescueship" (v "ownership") wore off, I realized it was just an
    oversized
    *4* digit DVM given that I never needed more accuracy/precision than
    that!
    And, surely wasn't going to PAY to have it calibrated to 8+ digits!

    (here, bench space is far more precious than quality of kit!)

    Going off BW * tr = 0.34 as the fastest edge a DSO can even assign a
    sample to, much less measure the rise time of accurately, I figure a 100 >>> MHz scope is too sluggish to calibrate a 5ns pulser on its fastest
    setting. /shrug

    The 0.34 is a relic of the past, when scopes were gaussian. Most
    scopes these days are peaked to meet their bandwidth claim, so even if
    they do make their -3 dB spec they ring like bells.

    If a scope is an honest 100 MHz, with a 3.5 ns Trr, it should be OK to
    measure a 5 ns edge; just math it.

    Or get an old Tek 20 GHz sampler.




    Keysight claims DSOs with BW < 1 GHz tend to have Gaussian responses and
    BW > 1 Ghz are maximally flat, but this may only apply for Keysight scopes:

    <https://f.hubspotusercontent40.net/hubfs/281197/Keysight_Evaluating_Oscilloscopes_AppNote_CControls.pdf>


    I don't know if anyone's evaluated what the response of the inexpensive
    Rigol scopes that are my work horses are, it's probably not particularly anything but the captures here don't make it seem like it's very peaked,
    at least:

    <https://www.eevblog.com/forum/testgear/rigol-ds1054z-bandwidth/50/>

    For 10% accuracy the difference between a maximally flat and Gaussian response don't matter much according to the first reference, for 3%
    quite a bit more.

    A pulser is a nice thing to have if just for checking loop stability
    sometimes, it don't have to be perfect

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From bitrex@21:1/5 to jlarkin@highlandsniptechnology.com on Wed Apr 27 13:17:24 2022
    On 4/27/2022 10:31 AM, jlarkin@highlandsniptechnology.com wrote:
    On Tue, 26 Apr 2022 22:59:24 -0400, bitrex <user@example.net> wrote:

    On 4/26/2022 9:49 PM, Don Y wrote:
    On 4/26/2022 8:28 AM, bitrex wrote:
    On 4/26/2022 11:18 AM, bitrex wrote:
    The HP 8082 uses ECL you can't get no mo, and looks like a PITA to
    repair:

    <https://youtu.be/09zhUbJl37w>

    Far as I can tell its slower smaller cousin the 8012a is all
    discrete-on-card though, yeah? It looks that way from the service
    manual but I haven't checked every thing.

    <https://www.keysight.com/us/en/assets/9018-03164/user-manuals/9018-03164.pdf>


    A 5ns rise time is still useful for a number of jobs, and I can get a >>>>> dodgy unit for next to nothing locally. I figure if I use it once a
    year it might be worth trying to fix up if it doesn't require exotic >>>>> parts.

    You can often pick up used kit from local tech firms, universities
    (excellent
    source of kit as they often dump everything they purchased for a GRANT
    project
    when the grant is over), etc.  Some firms just contract disposal of
    their kit
    to a firm; others sell at auction (which may or may not be "public").
    Knowing
    folks at these places is a great way to get the inside track...


    There is a re-seller like that near me with several dozen "tested"
    3478As bench DMMs available for $150 per (better test the AC section
    though as it uses an unobtaninum part) and another place will calibrate
    it for $50.

    <https://youtu.be/9v6OksEFqpA>

    I think I'll pick up a couple I used them in college & they're still
    nice meters.


    I don't think I own equipment fast enough to calibrate a refurbed 8082 >>>> anyway, even if it's not the ECL that's the problem

    Yeah, I rescued an HP 3458A many years ago.  After the initial "pride of >>> rescueship" (v "ownership") wore off, I realized it was just an oversized >>> *4* digit DVM given that I never needed more accuracy/precision than that! >>> And, surely wasn't going to PAY to have it calibrated to 8+ digits!

    (here, bench space is far more precious than quality of kit!)

    Going off BW * tr = 0.34 as the fastest edge a DSO can even assign a
    sample to, much less measure the rise time of accurately, I figure a 100
    MHz scope is too sluggish to calibrate a 5ns pulser on its fastest
    setting. /shrug

    The 0.34 is a relic of the past, when scopes were gaussian. Most
    scopes these days are peaked to meet their bandwidth claim, so even if
    they do make their -3 dB spec they ring like bells.

    If a scope is an honest 100 MHz, with a 3.5 ns Trr, it should be OK to measure a 5 ns edge; just math it.

    Or get an old Tek 20 GHz sampler.




    Keysight claims DSOs with BW < 1 GHz tend to have Gaussian responses and
    BW > 1 Ghz are maximally flat, but this may only apply for Keysight scopes:

    <https://f.hubspotusercontent40.net/hubfs/281197/Keysight_Evaluating_Oscilloscopes_AppNote_CControls.pdf>

    I don't know if anyone's evaluated what the response of the inexpensive
    Rigol scopes that are my work horses are, it's probably not particularly anything but the captures here don't make it seem like it's very peaked,
    at least:

    <https://www.eevblog.com/forum/testgear/rigol-ds1054z-bandwidth/50/>

    For 10% accuracy the difference between a maximally flat and Gaussian
    response don't matter much according to the first reference, for 3%
    quite a bit more.

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Phil Hobbs@21:1/5 to jlarkin@highlandsniptechnology.com on Wed Apr 27 14:14:00 2022
    jlarkin@highlandsniptechnology.com wrote:
    On Wed, 27 Apr 2022 04:15:50 -0400, Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net> wrote:

    Don Y wrote:
    On 4/26/2022 7:59 PM, bitrex wrote:
    You can often pick up used kit from local tech firms, universities
    (excellent
    source of kit as they often dump everything they purchased for a
    GRANT project
    when the grant is over), etc.  Some firms just contract disposal of >>>>> their kit
    to a firm; others sell at auction (which may or may not be "public"). >>>>> Knowing
    folks at these places is a great way to get the inside track...

    There is a re-seller like that near me with several dozen "tested"
    3478As bench DMMs available for $150 per (better test the AC section
    though as it uses an unobtaninum part) and another place will
    calibrate it for $50.

    Resellers increase the price but usually don't add much "value".  You want >>> to find the guy *he* buys from (usually someone at ABC Tech Corporation). >>>
    I think I'll pick up a couple I used them in college & they're still
    nice meters.

    I don't think I own equipment fast enough to calibrate a refurbed
    8082 anyway, even if it's not the ECL that's the problem

    Yeah, I rescued an HP 3458A many years ago.  After the initial "pride of >>>>> rescueship" (v "ownership") wore off, I realized it was just an
    oversized
    *4* digit DVM given that I never needed more accuracy/precision than >>>>> that!
    And, surely wasn't going to PAY to have it calibrated to 8+ digits!

    (here, bench space is far more precious than quality of kit!)

    Going off BW * tr = 0.34 as the fastest edge a DSO can even assign a
    sample to, much less measure the rise time of accurately, I figure a
    100 MHz scope is too sluggish to calibrate a 5ns pulser on its fastest >>>> setting. /shrug

    Most of the products I've designed have intentionally NOT required close >>> tolerances on anything.  That adds cost -- in parts or calibration labor. >>> So, we design products that rely on other means to make sense of their
    observations (ratiometric or other "self calibration" tricks).

    [It's not uncommon to have manufacturing tolerances of -60%, +300%.
    Easy to
    accommodate if you are smart about it.]

    A pity you didn't just replace NIST. ;)


    Another NOLA story: we'd send drawings out to machine shops and get
    stuff that didn't fit. They responded that we should send them
    drawings with tolerances, and circle some in red with the note HOLD.

    Sounds like my approach to modelmaking.

    Life's too short to worry about the small stuff, I guess.

    The Silicon Bayou and similar plans never seemed to work out. That's
    one reason why I left.

    Yeah, things don't go as well when the clean room guys are sneaking into
    the tool core for a smoke. ;)

    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 Don Y@21:1/5 to Don Y on Sat Apr 30 02:44:10 2022
    On 4/27/2022 2:50 AM, Don Y wrote:
    On 4/27/2022 1:15 AM, Phil Hobbs wrote:
    Don Y wrote:

    [It's not uncommon to have manufacturing tolerances of -60%, +300%. Easy to >>> accommodate if you are smart about it.]

    A pity you didn't just replace NIST. ;)

    Lots of things don't need to be qualified in "engineering units".

    How do you test that the *hammer* you are building, today, is as good
    as the hammers you've built in the past? Or, a screwdriver? Just
    how "durable" should the finish on a tape rule be?

    "Quest" (TV Network) just aired a show, "Modern Marvels", in which
    such a device was shown in use. Apparently it's a rerun of a show from
    ~6 mos ago. I can't seem to find it online (in a free venue).

    <https://www.stanleyblackanddecker.com/article/stanley-black-decker-featured-upcoming-modern-marvels-machines-episode-airing-history>

    It would have been more interesting if they'd shown how tape rules are "exercised", hammer handles broken, screwdriver tips sheared off,
    tool finishes abraded, etc.

    For folks used to seeing things done with "conventional" units of measure,
    it would be eye-opening!

    They *do* use some "laboratory" tools to augment their collected data.
    E.g., rockwell hardness tester to determine the hardness of the steel
    used in the tool, etc. And, the fixtures are calibrated to produce reproducible tests -- so 1135 hammer strikes today represents the
    same amount of wear that it did 30 years ago, and a tape rule dropped
    from 50 inches experiences the same sort of impact shock that it did
    30 years ago, and...

    What's particularly interesting is how many tools are easily broken by
    careless users. A "nominal" male can easily tear the tip off a #0
    Philips screwdriver. And, most can do that on a #1 tip as well!
    But, at #2 and larger, you really need to be a bit of a gorilla...
    (and capable of holding the screwdriver's tip *in* the screwhead
    lest it "cam out")

    And, I suspect everyone has a cabinet tip screwdriver whose blade is
    no longer flat (overtorqued, bending the ends out of the plane of the
    flats). Or, a handle that "spins" on the shaft (cuz you tried to
    apply excessive torque with a pair of vice grips)? Or, a wood
    chisel that seemed like it would be a great tool for cutting
    aluminum gutters? Or, a screwdriver handle that has been cracked because someone thought it would make a good *chisel*?

    [who, besides the manufacturer, would know how to interpret those data?
    What units? How to evaluate relative to other vendors' products?]

    How do you verify that the (pharmaceutical) tablet that you produced NOW
    is as good as the one you produced 5 milliseconds earlier?

    Ans: you monitor something that correlates well with the parameters
    of the tablet that are important to the regulators AND your own QC.

    In addition to being concerned with the amount of actives in the tablet, regulators are concerned primarily with *consistency* (!) of actives in
    a tablet, overall weight, dissolution time and disintegration time.
    They're not going to let you sell a bottle with 300mg tablets and
    100mg tablets on the argument that the 300mg tablet just has 200 extra
    mg of binders and lubricants in its excipients!

    [Your QC will step in before the regulator ever sees such an abomination]

    Actives can only be determined by assay -- which is destructive in nature.
    As are dissolution and disintegration tests.

    All of these tests are far too slow to keep up with the production rate
    of a high speed tablet press (1M+ tablets/hour). But, you can get an
    insight into some of them -- weight, disintegration time (and other
    attributes that may be of interest in certain products -- like
    hardness for effervescents) -- by monitoring the *forces* encountered
    by the tablet at various stages of its formation and production.

    [There's no need to express forces in engineering units -- as long as the calibration is consistent from press to press, lab to production, etc.
    Early controllers had an analog meter that showed the current state
    of the process -- with "percent deviation" labels (percent of WHAT?)]

    As you are dealing with a constant geometry (the cavity in which the
    tablet is formed), higher forces indicate more material (granulation)
    must be present in that cavity. Lower forces correspond with lower
    amounts of material. I.e., you have a good predictor of *weight*
    (part of the scale up process is characterizing the relationship
    of force to tablet weight in the lab, before releasing to manufacturing).
    And, as such, you can put limits on measured forces to determine which
    tablets are likely over/underweight. And, can do this at production speeds, dispatching "bad" tablets on the fly while keeping good tablets ("swatting"
    the bad ones off to the side).

    You can also learn a lot about the condition of the tooling that you are
    using (each product has a different set of tools) to determine wear
    and other "maintenance" issues (e.g., a broken punch tip is bad news
    as it means there's likely a tablet with a shard of metal in it!).

    [There's a second school of thought that applies a constant force to
    the tablet during formation and monitors the resulting thickness, in
    real time -- by monitoring the motion of the compression rollers
    as the tablet's tooling passes between them (not using engineering
    units but, rather, fixed thresholds determined in the lab, at scale up).

    But, these require significant mechanisms to move at reasonably high
    rates... I seriously wonder if they can be as sensitive as simply monitoring forces.

    They also suffer from not being able to address all issues that
    force monitoring can detect -- like the force required to eject
    a formed tablet from its die (to detect barreling of dies and
    a crude indication of capping).]

    [Does the consumer care if a particular batch of tablets have a friability
    of 1.2%? Or, variations of hardness on the order of 2KP? Or, a dissolution time that varies by 4% in a particular sample of tablets?]

    If the tablets are going to be *coated*, then friability is hugely important (as a coating pan subjects the tablets to high abrasive forces). So, while
    not directly controlled for regulators, it eventually factors into the
    quality of the tablet (if regulator notices your coated tablets are "all coating" and "little tablet"!)

    In many cases, you rely on some other (external) determinant of "acceptable quality" and the goal is just to ensure repeatability of process. E.g., those "good" tablets were produced with 4.5 bogounits of force exerted during the compression phase; make sure all of them experience a similar force. Or, a sample of those hammers struck the test anvil 1825 times, on average, before
    the handle snapped; the competitor's hammers broke at 1615 strikes, on average.
    Etc.

    Statistical Process Control becomes more important than traditional control theory (use a conventional control loop and wrap SPC around that)

    Because you are dealing with repetitive processes, you're concerned with
    how repeatable/consistent that process is. Is swaging station #7 producing
    a wider distribution of tip shear strengths than station #2? Why??

    This is particularly important for a tablet press which can actually be ~100+ presses rolled into one! A 75 station press has 75 sets of tools -- upper, lower punches and a die per station. Each has manufacturing tolerances and experiences wear at different rates (based on its "tableting history").

    So, a manufacturer makes sure he keeps each upper, lower, die together -- along with noting which station they occupied -- so their results are more repeatable on the next run (imagine the number of mix-and-match combinations possible!).

    But, each station is measurably different in terms of physical characteristics. So, any information you observe about the production of a tablet on station #1 doesn't directly translate to the production of a tablet on station #2 -- just a few ms later! A longer punch can make the force higher (or lower -- depends on which punch) for the same amount of "fill"

    So, ANY CONTROL ACTIONS that you take to keep the tablet weight (as expressed by compression force) based on observations of the formation event for station #1 can be "wrong" for the tablet being formed by station #2! Repeat...

    [We've actually had customers disable the control system to determine if
    it might be INCREASING variability in tablets! In practical terms, you end
    up severely overdamping the loops to ensure the process doesn't oscillate purely as a consequence of the variations in *tooling*! Hence the value of looking at the distributions of forces (weights) per-tooling-station and
    using THAT information to decide when the process is stable.]

    A tablet press is often double-sided -- meaning a tablet is formed on the
    front side of the machine while another is being formed on the back side.
    So, stations #1 and 38 are each in the same state of tablet formation;
    ditto #2 & 39...

    But, the front and back sides of the machine have different cam profiles,
    wear patterns, etc. -- due to mechanical tolerances. And, different
    feeders, control loops, etc. So, a tablet formed by the punches in station
    #1 on the FRONT side of the press can have different characteristics than a tablet formed in that station when it's on the BACK side of the press.

    And, if you're using a two (or three!) sided press to make a bi-layer (tri-layer) tablet, the observations of one "side" of the tablet's
    production directly factor into the observations of the second (third)
    side!

    It is a **delightful** control system problem! Someday, they'll be able
    to weigh individual tablets at the 2M/hr rate and much of this will be unnecessary (though likely retained as an inner control loop).

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)