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From: Bill Sloman <bill.sloman@ieee.org>
Newsgroups: sci.electronics.design
Subject: Re: CO2 Funny
Date: Mon, 27 May 2024 15:05:14 +1000
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On 27/05/2024 4:22 am, Edward Rawde wrote:
> "Bill Sloman" <bill.sloman@ieee.org> wrote in message news:v2uhs7$39s6m$1@dont-email.me...
>> On 26/05/2024 4:38 am, Edward Rawde wrote:
>>> "Bill Sloman" <bill.sloman@ieee.org> wrote in message news:v2na16$1nvei$1@dont-email.me...
>>>> On 23/05/2024 3:52 am, john larkin wrote:
>>>>> On Wed, 22 May 2024 18:10:58 +0100, Pomegranate Bastard <pommyB@aol.com> wrote:

<snip>

>> It usually takes a while to work out why they did it that way, and it's pretty much essential to spend that time before you start
>> fiddling with the circuit. That wasn't true of the guy who'd put in the 741. He was very much in the John Larkin "if it sort of
>> works, ship it" camp.
> 
> Which of John Larkin's products have you purchased and tested and what improvement
> do you think should have been made before it was shipped?

Absolutely none of them. The timing gear he sells to the American 
National Ignition Facility is based on a 1978 Hewlett Packard scheme,
written up in their journal, and it depends on starting up a 50MHz 
free-running oscillator in a very predictable way.

Faster oscillators have less jitter, and while synchronising to a 
continuously running faster oscillator twice may introduce extra jitter, 
the net jitter on the time delay can be quite a bit less.

I had much the same problem in 1988 and went for a free-running 800MHz 
oscillator.

It turns out that the first version of John's 50MHz oscillator had a 
nasty - if small - sub-harmonic oscillation and he's finally found a 
better version.

>> Management liked him because he was quick. Production was less enthusiastic.
> 
> Management likely expected that problems would be found which would have to be dealt with at a later time.

I got to cleanup his mess ten years later, and only because some of the 
parts he had used had gone obsolete.

It didn't mention another error - his 741 had to drive a few metres of 
shielded pair, which was a big enough capacitative load to make it 
oscillate, to which his solution had been to hang on a 100uF 
electrolytic, so the oscillation was at too low an amplitude to be 
visible. There's a standard solution for that - National Semiconductor 
Applications note AN-4 Fig.14. which he should have known about.

I'd certainly had to deal with it more than ten years earlier
> 
>> Would you be kind enough to give your opinion of John Larkin once per month instead of twice per day?
> 
>> When he starts claiming to do electronic design once a month rather than twice a day.
> 
> I still don't see why it matters so much when the two of you are in different countries and, correct me if I'm wrong,
> you've never used or tested any of JL's products.

One of his standard insults is to claim that his critics don't design stuff.

> You can't deny that JL has a successful business.
> Whether his business would be more successful if he adopted different design techniques is not something I wish to go into
> because it simply doesn't matter to me.

He's the electronic equivalent of a vanity publisher. He give people who 
can't design their own electronics, bespoke electronic solutions to the 
problems that they think they have. I did a bit of that at Nijmegen 
University in the Netherlands, and most of what I found myself doing was 
getting people to recognise that they had a standard problem for which 
they could buy a standard solution off the shelf.

-- 
Bill Sloman, Sydney