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From: liz@poppyrecords.invalid.invalid (Liz Tuddenham)
Newsgroups: sci.electronics.design
Subject: Re: squeezing a field
Date: Fri, 25 Oct 2024 09:37:20 +0100
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Bill Sloman <bill.sloman@ieee.org> wrote:

> On 25/10/2024 7:56 am, Liz Tuddenham wrote:
> > john larkin <jl@glen--canyon.com> wrote:
> > 
> >> On Thu, 24 Oct 2024 18:45:20 +0200, Lasse Langwadt <llc@fonz.dk>
> >> wrote:
> > [...]
> >>> plugging numbers pulled out of thin air into LTSpice is better that
> >>> doing the actual measurement?
> > 
> >> It is for people who don't actually work with real parts. 
> 
> Actually, it is extremely useful for people who work with real parts and
> who want to know exactly what is going on. You can see stuff that is 
> very hard to measure on real parts.
> 
> > Peter Baxandall (of tone control and QUAD amplifier fame) claimed to use
> > analogue computing to work out his designs  i.e. He built prototypes and
> > measured them.
> 
> But he understood what he was measuring - a least most of the time.
> His revolutionary ideas about capacitor microphones and the patent 
> application he made fell down when he found out about the Philips 
> capacitative pressure gauges which had been exploiting the same 
> principle for about a decade before.

If anything, that enhances his reputation rather than diminishing it,  A
single inventor working on a project in his spare time compared with a
laboratory-full of specialists working full-time on commercial projects
(if I remember rightly) one of which was almost certainly partly
financed by the Ford Motor Company.

> 
> This played out in the pages of Wireless World, between the first and
> second parts of a two part article. 

The articles were in WW Nov/Dec 1963.  At the end he refers to two Dutch
papers:

Philips Technical Review Vol9 Nr12  1947/48  pp357-363

Omroep-technische Mededelingen  Feb15 1961

These are both describing to low-noise condenser microphones but he
points out that they don't have some of the desirable features of his
design.


>I don't think he mentioned the Philips pressure gauges,
 >but I've got a 1954 reference to them in my 
> 1970 Ph.D. thesis

That may have been the article on capacitive pressure guages for car
engines in the Philips Technical Review.  Their main problem was that
the temperatures and pressures they were trying to measure gave a short
diaphragm life if the diaphragm was thin enough to respond to the
required frequency range with sufficient sensitivity.


-- 
~ Liz Tuddenham ~
(Remove the ".invalid"s and add ".co.uk" to reply)
www.poppyrecords.co.uk