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Re: about electronics

From Bill Sloman <bill.sloman@ieee.org>
Newsgroups sci.electronics.design
Subject Re: about electronics
Date 2026-04-29 14:27 +1000
Organization A noiseless patient Spider
Message-ID <10ss1c9$3l5f0$1@dont-email.me> (permalink)
References (8 earlier) <bqgvukdpqav7gpado09tg5g7lsh455q8ob@4ax.com> <10spohh$2vate$2@dont-email.me> <osm1vkljfruma48ancfu6o719gjblhbot4@4ax.com> <10sqqgs$3a6h3$1@dont-email.me> <e7p2vktan5glu99odc76c4bi3pj0veo1rh@4ax.com>

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On 29/04/2026 11:58 am, john larkin wrote:
> On Wed, 29 Apr 2026 03:24:41 +1000, Bill Sloman <bill.sloman@ieee.org>
> wrote:
> 
>> On 29/04/2026 2:22 am, john larkin wrote:
>>> On Tue, 28 Apr 2026 17:44:47 +1000, Bill Sloman <bill.sloman@ieee.org>
>>> wrote:
>>>
>>>> On 28/04/2026 6:24 am, john larkin wrote:
>>>>> On Sun, 26 Apr 2026 21:34:01 +1000, Bill Sloman <bill.sloman@ieee.org>
>>>>> wrote:
>>>>>
>>>>>> On 26/04/2026 4:08 am, john larkin wrote:
>>>>>>> On Sun, 26 Apr 2026 02:20:43 +1000, Bill Sloman <bill.sloman@ieee.org>
>>>>>>> wrote:
>>>>>>>
>>>>>>>> On 26/04/2026 1:14 am, john larkin wrote:
>>>>>>>>> On Sat, 25 Apr 2026 15:07:29 +1000, Bill Sloman <bill.sloman@ieee.org>
>>>>>>>>> wrote:
>>>>>>>>>
>>>>>>>>>> On 25/04/2026 3:38 am, john larkin wrote:
>>>>>>>>>>> On Fri, 24 Apr 2026 10:10:53 -0700, Buzz McCool
>>>>>>>>>>> <buzz_mccool@yahoo.com> wrote:
>>>>>>>>>>>
>>>>>>>>>>>> On 4/24/2026 8:55 AM, john larkin wrote:
>>>>>>>>>>>>> Summary: very few people understand electronics.
>>>>>>>>>>>>
>>>>>>>>>>>> Edit: Very few people understand electronics as well as you.
>>>>>>>>>>>>
>>>>>>>>>>>> A few years ago you had some posts with typical interview questions you used.
>>>>>>>>>>>> I collected these and sent them to my now freshly minted EE child who will
>>>>>>>>>>>> be starting work next month. So don't think that people aren't listening.
>>>>>>>>>>>
>>>>>>>>>>> I hope your kid understands electricity. Most ce/ee grads don't, and
>>>>>>>>>>> AI may make them into grocery store clerks.
>>>>>>>>>>
>>>>>>>>>> Probably not. AI is essentially mindless plagiarism.
>>>>>>>>>> It gets stuff right about 90% of the time, rather like junior engineers,
>>>>>>>>>> but needs to be backed up by people with deeper understanding
>>>>>>>>>>
>>>>>>>>>>>> If you have more pearls of wisdom to share, please do. Years ago Phil shared
>>>>>>>>>>>> an article about how the front page of ceramic cap datasheets are a pack of
>>>>>>>>>>>> lies, which was very revealing to me. Even now in the 4th quarter of my career
>>>>>>>>>>>> I want to understand more about electronics.
>>>>>>>>>>>>        
>>>>>>>>>>> Ceramic caps are awful. Buy a 22uF 10v cap and you might get 3 uF at
>>>>>>>>>>> 10v.
>>>>>>>>>>
>>>>>>>>>> Ceramic caps can be voltage dependent - but it does depend a lot on the
>>>>>>>>>> actual ceramic. Reading the data sheet carefully can be informative.
>>>>>>>>>
>>>>>>>>> It's rare for a ceramic cap data sheet to even mention the cap fallout
>>>>>>>>> with voltage, much less quantify it.
>>>>>>>>>
>>>>>>>>>> NPO ceramics are about as good as it gets. Ceramics with higher
>>>>>>>>>> dielectric constants offer more - but less predictable - capacitance.
>>>>>>>>>
>>>>>>>>> NPOs are great, but only come in small values.
>>>>>>>>
>>>>>>>> That's what I just said.
>>>>>>>>
>>>>>>>>>> https://en.wikipedia.org/wiki/Ceramic_capacitor
>>>>>>>>>>
>>>>>>>>>> does talk about this. Class 1 ceramic capacitors can be very stable.
>>>>>>>>>> Class 2 offers more capacitance but less stability, and Class 3 offers
>>>>>>>>>> loads of capacitance in a small package but it can vary a great deal.
>>>>>>>>>> John Larkin doesn't seem to read data sheets in detail, and he may have
>>>>>>>>>> bought a class 3 capacitor for a Class 2 application.
>>>>>>>>>
>>>>>>>>> Classes, and categories like Z5U, are very crude. One has to test caps
>>>>>>>>> when it matters, and then hope one can buy consistent parts.
>>>>>>>>
>>>>>>>> Crude they may be, but you didn't even mention that they existed.
>>>>>>>>
>>>>>>>>> We do buy big reels of custom-mixed caps with defined behaviors and
>>>>>>>>> tempcos. I had Capax make us 5000 pieces of 3.3 pF 0805's, with -4700
>>>>>>>>> ppm/degC tempco. They came out close. We have a lifetime supply.
>>>>>>>>
>>>>>>>> That implies more technical expertise than you exhibited above. Did one
>>>>>>>> of your customers spell out the details, or that pesky Ph.D. that you fired?
>>>>>>>
>>>>>>> Neither. I use the NTCs to temperature compensate my instant-start LC
>>>>>>> oscillators. FR4 has a radical positive TC. I typically wind up with a
>>>>>>> parabolic frequency tempco, flat around 35c.
>>>>>>>
>>>>>>> Most things work like that. Compensate the first-order term, and
>>>>>>> what's left is mostly second-order.
>>>>>>
>>>>>> The instant start LC oscillators are a bad idea. You can get much better
>>>>>> timing out of a continuously running oscillator - you need two
>>>>>> interpolation circuits rather than just one to find out where your
>>>>>> interval started as well as where you want it to end, but the lower
>>>>>> jitter on the continuously running oscillator makes that a better choice.
>>>>
>>>> <snipped self-advertising>
>>>>
>>>>
>>>>> There are lots of ways to make a triggered delay with XO accuracy and
>>>>> jitter. Most involve a lot of insertion delay, and some have analog
>>>>> s/h drift that is work to correct for.
>>>>
>>>> The ones that involve less insertion delay are more interesting.
>>>>
>>>>> Many users want minimal insertion delay.
>>>>
>>>> Most of them want the timing ramp to start a few nanoseconds before they
>>>> know they need to start it. Thiotimoline would solve that problem, if it
>>>> existed.
>>>>
>>>> https://en.wikipedia.org/wiki/Thiotimoline
>>>>
>>>> It can make more sense to redesign the experiment so that you can
>>>> control when it starts, but customers don't want to do that - they do
>>>> try to buy their way out of bad system design choices.
>>>>
>>>>> The instant-start oscillator is great in that respect.
>>>>
>>>> But not in others.
>>>>
>>>>> After it starts, we observe it for a while
>>>>> and phase-lock it to a good OCXO but keep the timing based on the
>>>>> trigger.
>>>>
>>>> Which inserts a delay.
>>>
>>> About 3 nanoseconds. If the triggered oscillator is accurate and
>>> low-jitter on its own, we can observe it and phase lock it at leisure.
>>> No rush.
>>
>> If you need to adjust the frequency, there's an accumulating phase error
>> until you have got the frequency right. You can't get the frequency
>> right in 3 nanoseconds.
> 
> Sure. It might take 10 usec or so to observe and lock. If the LC is
> very good, it doesn't drift much meanwhile.
> 
> I think the HP took much longer to close the loop.
> 
> 
> 
>>
>>> The HP 5359A time synthesizer used a triggered delay-line oscillator
>>> and used a slow complex heterodyne system to phase-lock it to an OCXO.
>>> Similar idea. But they didn't have access to fast ADCs and DACs like
>>> we do now.
>>>
>>> My favorite triggered oscillator uses a coaxial ceramic resonator, but
>>> that has lots of real-world problems.
>>>
>>>>>> You can't make a silk purse out of a sow's ear.
>>>>>
>>>>> That's clever. Did you make that up?
>>>>
>>>> Like the emitter-coupled monostable, it isn't original.
>>>>
>>>>> Here's our benchtop DDG.
>>>>>
>>>>> https://highlandtechnology.com/Product/P500
>>>>>
>>>>> One nice feature is the GaN output stages that make super fast clean
>>>>> pulses over a wide voltage range.
>>>>
>>>> Pity about the instant-start timing oscillator.
>>>
>>> OK, you design a DDG and show me how.
>>
>> One designs a digital delay generator for a particular customer - if you
>> are lucky, a group of customers. I haven't got the customers for whom
>> I'd generate the system design. The one I did build was for the
>> Cambridge Instruments stroboscopic electron microscope.
> 
> How did that work?

800MHz local oscillator phase locked to a good 1OMHz crystal oscillator.

We worked out when the start pulse had come in w.r.t. the local 
oscillator to about about 5psec (which took about 20nsec) and generated 
an output from the appropriate output from the 800MHz edge one cycle 
before the right time and generated a fine delay (to about 5psec).

The first try at the 800MHz oscillator didn't work and it's quick and 
dirty replacement had 60osec of jitter. We could have done better if 
we'd had to but our sampling pulse was 500psec wide and the 10pec was 
just the boss indulging in specmanship, and we had  more urgent problems 
to deal with.

-- 
Bill Sloman, Sydney

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about electronics john larkin <jl@glen--canyon.com> - 2026-04-24 08:55 -0700
  Re: about electronics Bill Sloman <bill.sloman@ieee.org> - 2026-04-25 02:14 +1000
    Re: about electronics john larkin <jl@glen--canyon.com> - 2026-04-24 09:39 -0700
      Re: about electronics Bill Sloman <bill.sloman@ieee.org> - 2026-04-25 03:32 +1000
        Re: about electronics john larkin <jl@glen--canyon.com> - 2026-04-24 10:46 -0700
          Re: about electronics Bill Sloman <bill.sloman@ieee.org> - 2026-04-25 14:44 +1000
            Re: about electronics john larkin <jl@glen--canyon.com> - 2026-04-25 08:03 -0700
              Re: about electronics Bill Sloman <bill.sloman@ieee.org> - 2026-04-26 02:28 +1000
                Re: about electronics john larkin <jl@glen--canyon.com> - 2026-04-25 10:56 -0700
                Re: about electronics Bill Sloman <bill.sloman@ieee.org> - 2026-04-26 21:27 +1000
              Re: about electronics Bill Sloman <bill.sloman@ieee.org> - 2026-04-26 21:11 +1000
              Re: about electronics Bill Sloman <bill.sloman@ieee.org> - 2026-04-26 21:16 +1000
              Re: about electronics Bill Sloman <bill.sloman@ieee.org> - 2026-04-26 21:50 +1000
          Re: about electronics Nioclás Pól Caileán de Ghloucester <thanks-to@Taf.com> - 2026-04-25 17:52 +0000
            Re: about electronics john larkin <jl@glen--canyon.com> - 2026-04-25 11:17 -0700
              Re: about electronics Nioclás Pól Caileán de Ghloucester <thanks-to@Taf.com> - 2026-04-26 17:12 +0000
        Re: about electronics someone <2a59d59e3809f827ce709d3815e3950eef4a6a93af5557a93a7fdfba71460843@example.com> - 2026-04-26 05:45 +0000
          Re: about electronics john larkin <jl@glen--canyon.com> - 2026-04-26 03:29 -0700
          Re: about electronics Bill Sloman <bill.sloman@ieee.org> - 2026-04-26 20:55 +1000
            Re: about electronics Someone <864c855e3d64399dc06fa30ebb75526c2c2e73db7216b16a3d4cf03e8a52ec3b@example.com> - 2026-04-28 20:15 +0000
              Re: about electronics Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net> - 2026-04-28 16:39 -0400
                Re: about electronics someone <2a59d59e3809f827ce709d3815e3950eef4a6a93af5557a93a7fdfba71460843@example.com> - 2026-04-30 05:30 +0000
                Re: about electronics Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net> - 2026-04-30 11:19 +0000
                Re: about electronics someone <2a59d59e3809f827ce709d3815e3950eef4a6a93af5557a93a7fdfba71460843@example.com> - 2026-05-05 18:15 +0000
                Re: about electronics Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net> - 2026-05-05 19:10 +0000
          Re: about electronics Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net> - 2026-04-26 12:53 +0000
          Re: about electronics john larkin <jl@glen--canyon.com> - 2026-04-26 07:57 -0700
            Re: about electronics Bill Sloman <bill.sloman@ieee.org> - 2026-04-27 01:33 +1000
      Re: about electronics Someone <864c855e3d64399dc06fa30ebb75526c2c2e73db7216b16a3d4cf03e8a52ec3b@example.com> - 2026-04-28 20:15 +0000
        Re: about electronics Bill Sloman <bill.sloman@ieee.org> - 2026-04-29 14:36 +1000
  Re: about electronics Buzz McCool <buzz_mccool@yahoo.com> - 2026-04-24 10:10 -0700
    Re: about electronics john larkin <jl@glen--canyon.com> - 2026-04-24 10:38 -0700
      Re: about electronics Buzz McCool <buzz_mccool@yahoo.com> - 2026-04-24 11:22 -0700
      Re: about electronics Bill Sloman <bill.sloman@ieee.org> - 2026-04-25 15:07 +1000
        Re: about electronics john larkin <jl@glen--canyon.com> - 2026-04-25 08:14 -0700
          Re: about electronics Bill Sloman <bill.sloman@ieee.org> - 2026-04-26 02:20 +1000
            Re: about electronics john larkin <jl@glen--canyon.com> - 2026-04-25 11:08 -0700
              Re: about electronics Bill Sloman <bill.sloman@ieee.org> - 2026-04-26 21:34 +1000
                Re: about electronics john larkin <jl@glen--canyon.com> - 2026-04-27 13:24 -0700
                Re: about electronics Bill Sloman <bill.sloman@ieee.org> - 2026-04-28 17:44 +1000
                Re: about electronics john larkin <jl@glen--canyon.com> - 2026-04-28 09:22 -0700
                Re: about electronics Bill Sloman <bill.sloman@ieee.org> - 2026-04-29 03:24 +1000
                Re: about electronics john larkin <jl@glen--canyon.com> - 2026-04-28 18:58 -0700
                Re: about electronics Bill Sloman <bill.sloman@ieee.org> - 2026-04-29 14:27 +1000
  Re: about electronics bitrex <user@example.net> - 2026-04-24 23:20 -0400
    Re: about electronics Don Y <blockedofcourse@foo.invalid> - 2026-04-24 21:50 -0700
      Re: about electronics john larkin <jl@glen--canyon.com> - 2026-04-25 08:26 -0700
      Re: about electronics Nioclás Pól Caileán de Ghloucester <thanks-to@Taf.com> - 2026-04-25 17:53 +0000
        Re: about electronics Don Y <blockedofcourse@foo.invalid> - 2026-04-25 11:34 -0700
          Re: about electronics Nioclás Pól Caileán de Ghloucester <thanks-to@Taf.com> - 2026-04-26 16:51 +0000
  Re: about electronics someone <2a59d59e3809f827ce709d3815e3950eef4a6a93af5557a93a7fdfba71460843@example.com> - 2026-04-26 05:45 +0000
    Re: about electronics john larkin <jl@glen--canyon.com> - 2026-04-26 03:39 -0700
      Re: about electronics Buzz McCool <buzz_mccool@yahoo.com> - 2026-04-28 15:38 -0700
        Re: about electronics Don Y <blockedofcourse@foo.invalid> - 2026-04-28 15:57 -0700
          Re: about electronics john larkin <jl@glen--canyon.com> - 2026-04-28 19:07 -0700
          Re: about electronics john larkin <jl@glen--canyon.com> - 2026-04-29 10:39 -0700
            Re: about electronics Bill Sloman <bill.sloman@ieee.org> - 2026-04-30 22:43 +1000
              Re: about electronics john larkin <jl@glen--canyon.com> - 2026-04-30 07:19 -0700
                Re: about electronics Bill Sloman <bill.sloman@ieee.org> - 2026-05-01 00:41 +1000
            Re: about electronics JM <sunaecoNoChoppedPork@gmail.com> - 2026-04-30 15:54 +0100
              Re: about electronics john larkin <jl@glen--canyon.com> - 2026-04-30 09:27 -0700
                Re: about electronics Bill Sloman <bill.sloman@ieee.org> - 2026-05-01 03:26 +1000
                Re: about electronics john larkin <jl@glen--canyon.com> - 2026-04-30 11:38 -0700
                Re: about electronics JM <sunaecoNoChoppedPork@gmail.com> - 2026-04-30 18:45 +0100
                Re: about electronics Don Y <blockedofcourse@foo.invalid> - 2026-04-30 13:00 -0700
                Re: about electronics Nioclás Pól Caileán de Ghloucester <thanks-to@Taf.com> - 2026-05-01 21:24 +0000
                Re: about electronics Bill Sloman <bill.sloman@ieee.org> - 2026-05-02 16:27 +1000
                Re: about electronics john larkin <jl@glen--canyon.com> - 2026-04-30 11:40 -0700
          Re: about electronics Don Y <blockedofcourse@foo.invalid> - 2026-05-03 14:35 -0700
            Re: about electronics john larkin <jl@glen--canyon.com> - 2026-05-03 14:41 -0700
            Re: about electronics joegwinn@comcast.net - 2026-05-03 19:54 -0400
              Re: about electronics Don Y <blockedofcourse@foo.invalid> - 2026-05-03 17:53 -0700
                Re: about electronics joegwinn@comcast.net - 2026-05-04 19:54 -0400
                Re: about electronics Don Y <blockedofcourse@foo.invalid> - 2026-05-04 17:33 -0700
                Re: about electronics joegwinn@comcast.net - 2026-05-05 13:35 -0400
                Re: about electronics Don Y <blockedofcourse@foo.invalid> - 2026-05-05 14:08 -0700
                Re: about electronics Nioclás Pól Caileán de Ghloucester <thanks-to@Taf.com> - 2026-05-05 21:29 +0000
                Re: about electronics Don Y <blockedofcourse@foo.invalid> - 2026-05-05 14:43 -0700
                Re: about electronics Bill Sloman <bill.sloman@ieee.org> - 2026-05-06 15:58 +1000

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