Re: squeezing a field

Bill Sloman <bill.sloman@ieee.org> wrote:

On 25/10/2024 7:37 pm, Liz Tuddenham wrote:

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.

 
The Philip's capacitative pressure gauges were scientific instruments,
not mass market products,

Yes,  some of those were developed for research into car engines.

... There may have been work on a product for the car market,
but they weren't cheap enough for that.

As far as I know the were never intended to be consumer products for car
users.

and if I could find them as graduate student,
somebody whose day job was at the Royal Radar Establishment in Malvern
should have been able to do that too.

Not always as easy in those days.  I found great difficulty getting any
electronics information because the librarian 'filtered'  research and
inter-library loan requests and blocked any she decided weren't for my
core research. 

My direct boss at George Kent in
Luton - Colin Hunter - had done his electronic appenticeship at the RRE
under Peter Baxandall. He wasn't any kind of single inventor working on
stuff in his spare time, but rather a full time expert exploiting the
resources his job gave him to follow his interests outside of his day job.

I was aware of that, but he wasn't working full-time on those projects
and he wasn't backed ny a team of researchers.  He was doing it
single-handed in his spare time, even though a blind eye might have been
turned when he was using 'the firms' equipment.

 

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.

 
Very likely. 1947/48 was pre-transistor. The planar process was invented
around 1955, and Fairchild started selling cheap planar transistors
around 1959. They revolutionised circuit design,and I latched onto that
in 1965 as a graduate student in chemistry. By 1963 you could suddenly
do a lot with planar transistors which hadn't been practical with
earlier parts.

Quote:
"This circuit was first successfully demonstrated in July 1959..."

He used SB240 Surface Barrier transistors in the RF part of the final
(1963) version but 0C44s in the prototypes.  Both versions used 0C45s in
the audio stages.

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