Re: big L

On Sat, 21 Dec 2024 22:01:36 +0000, liz@poppyrecords.invalid.invalid
(Liz Tuddenham) wrote:

Cursitor Doom <cd@notformail.com> wrote:
>

On Sat, 21 Dec 2024 11:35:54 -0800, john larkin <JL@gct.com> wrote:
 

On Sat, 21 Dec 2024 16:53:07 +0000, Cursitor Doom <cd@notformail.com>
wrote:
>

On Sat, 21 Dec 2024 11:16:18 -0500, legg <legg@nospam.magma.ca> wrote:
>

On Tue, 17 Dec 2024 06:58:32 -0800, john larkin <JL@gct.com> wrote:
>

What's the biggest inductor, the most Henries, that you know of? I
seem to recall some audio transformer that was something like 100 H.

>
The SAFT/Alcatel plant in Scarborough used to have
largish inductors for loading. Air-cored - ~10ft
on a side.
>
Your watch would stop, if you were too close.
>
Large L ? Who needs it?

>
In the olde days we used to have audio output transformers  for
impedance matching purposes, but modern amps don't seem to need 'em.

>
And long ago tubes were expensive so it made sense to get voltage gain
from interstage transformers.

 
Indeed. And that's just one aspect of it. The designers in the early
stage of toob development deserve huge respect for the performance
they were able to wring out of a single stage - and all just to save
the hard-pressed consumer back in the day a few sheckles.

>
Have a look at:
<http://www.poppyrecords.co.uk/httpdocs/other/AMC5.pdf>
as an example of incredibly efficient design.  It took the output from a
ribbon mic and raised it to 0dBm line level.  By using a mixture of
current and voltage feedback, it terminated the mic correctly without
the need for a terminating resistor, which would have wasted signal
power and generated Johnson noise.

link not valid from here . . . .

I only ever did commercially impractical valve circuits. Often
using one-off components that couldn't be replaced without
major toil.

One way of separating the hobby from work.

RL