Amplifer Design

[Cursitor Doom]

On Wed, 16 Oct 2019 17:38:14 -0700, Winfield Hill wrote:

Cursitor Doom wrote...

On 16 Oct 2019, Cursitor Doom wrote:

Well I'm mightily relieved you said that, Win, because I do happen to
have a very large amount of both polarities in stock. THANKS!!!

Just wondering if I should try to match pairs by Beta as closely as
possible. I have a nagging suspicion I really should make that extra
little bit of effort.

Although this is an old design, it adheres well to the BJT design
philopsohy I learned in the late 60s. Which is to rely on accurate
Ebers-Moll transconductance characteristics, and stay away from the
uncertain beta, and similar aspects of a transistor, in the circuit
design. So you don't need to match beta, Vbe, or other perameters.

Thanks, Win, that's a real plus, believe me.
I'm carrying out some other tests in the odd minutes I get between the
phone ringing and various people calling and have ascertained the
*actual* fault appears to be in one of the preceding stages. So at the
moment, it looks like there's nothing wrong with that "partially C-E
shorted bjt" - it's simply being driven into saturation by a chain of
cause and effect from an earlier stage where the true fault *does* lie.
I'm guessing this is not unusual when you have directly-coupled stages
like these, which I'm not so much accustomed to dealing with.
I'll be investigating further over the next 8 hours as and when time and
interruptions permit and will report back in due course....
Thanks again for your invaluable assistance!



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On Wednesday, 16 October 2019 17:37:41 UTC+1, jrwal...@gmail.com wrote:

On Wednesday, 16 October 2019 16:24:34 UTC+1, Winfield Hill wrote:
Jan Panteltje wrote...

I bought a 2400 W water boiler, for coffee that is.
Plugging it in did indeed boil 1.5 liter water in
about 3 minutes, but it also caused a dip ...

2400 watts, that's ridiculous. The most they sell
here is 1500 watts, that's more than fast enough.
Trade it in for a smaller one.

Not at all. I just checked the rating label on my "electric kettle".
(Almost every household in the UK has one of these.)
Mine is rated at 220 - 240V, 2500 - 3000W.

Most UK household mains supplies are about 240V single phase and
have a main fuse rated at 80 or 100A. Larger houses often have
3-phase 240V (phase to neutral) at 100A per phase.

(The "official" voltage is 230V but this is just for harmonisation
purposes with the rest of the EU. The specified tolerances allow
the real voltage to be around 240V for most areas.)

John

Domestic supplies are variously rated at 40A, 60A, 80A and 100A. 40 is common in 1&2 bed flats. There are also pre-war 30A supplies still in use, even in houses where one would expect much better. In my limited experience of the latter they coped with way above 30A well enough.

230v is the nominal voltage only - the target voltage is still 240v.


NT

 

[Jan Panteltje]

On a sunny day (Thu, 17 Oct 2019 08:00:46 -0000 (UTC)) it happened Cursitor
Doom <curd@notformail.com> wrote in <qo973e$2hf$2@dont-email.me>:

On Thu, 17 Oct 2019 06:46:42 +0000, Jan Panteltje wrote:

No, I think you mean 'Rosmalen', that was in March this year.
Did not go there, is a ham radio market, I do have a callsign though.
https://amateurzender.nl/events/radiomarkt-rosmalen/

Already have enough stuff

Same here! Far too much stuff in fact. Well, if you're not too far away
why not pop over and meet up at the next one? And don't worry - I'm not
gay!
:-D

So, now I am curious, where are you located then?
or is that only known to Russian agents ;-)?

I am all the way in the north of the Netherlands, 'Friesland'.
Well now anyways, lived all over the place.

 

[Jan Panteltje]

On a sunny day (Thu, 17 Oct 2019 08:13:45 -0000 (UTC)) it happened Cursitor
Doom <curd@notformail.com> wrote in <qo97rp$2hf$3@dont-email.me>:

On Thu, 17 Oct 2019 07:31:23 +0000, Jan Panteltje wrote:

Again, do you have a cellphone?

Yes, of course. HATE the damn thing, but there's no avoiding them. What
are you driving at, dear boy?

In that cellphone there is a lot of precision RF stuff, filtering etc,
mostly integrated in one chip that is smaller than even one of your mica caps...
If you like 'precision' filtering, then I have a super-conducting filter
from a cell[phone tower here....
At 70 degrees Kelvin the R of the inductors is zero, so the Q is enormous,
that filter is attenuating any out of band signals in the cellphone band (in the tower).
http://panteltje.com/pub/super_filter/super_filter_dewar_img_2557.jpg
also a bit of a boat-anchor
http://panteltje.com/pub/super_filter/super_filter_front_plate_img_2576.jpg

 

[Cursitor Doom]

On Thu, 17 Oct 2019 09:24:41 +0000, Jan Panteltje wrote:

> So, now I am curious, where are you located then?

Elsewhere in Yurp. It'll take me 48hrs to get to that hamfest so there's
no excuse for you not to make the effort from your position "just up the
road."

> or is that only known to Russian agents ;-)?

Believe me, it's not the Russians you need to worry about.

> I am all the way in the north of the Netherlands, 'Friesland'.

Ah yes, I know it well (the location anyway). So that's a date then! Next
March at the hamfest. I'll be wearing a red carnation, bright orange
flared trousers and a tinfoil hat. See you there!



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