Re: The Venerable 741

On Mon, 4 Nov 2024 14:11:05 -0500, bitrex <user@example.net> wrote:

On 11/4/2024 10:21 AM, john larkin wrote:

On Sun, 3 Nov 2024 22:24:12 -0500, bitrex <user@example.net> wrote:
 

On 11/3/2024 5:17 PM, Jeroen Belleman wrote:

On 11/3/24 23:10, Jeroen Belleman wrote:

On 11/3/24 19:07, Cursitor Doom wrote:

It's been around an awfully long time and there are far better
alternatives out there. But is there still a case for using them in
certain niche applications in 2024?

>
I've used them in power supply regulators exposed to radiation.
Being old designs and all-NPN, they're pretty rad-hard.
>
Jeroen Belleman

>
Blimey, I just checked: It isn't all-NPN! Fortunately
for me, it still kept working under irradiation...
>
Jeroen Belleman

>
Have to go back to Jim Thompson's MC1530 era to get that:
>
<http://www.elektronikjk.com/elementy_czynne/IC/MC1530-2.pdf>

 
He probably designed that without Spice.
 
The first IC opamp I tried was made by GE. All NPN, with an internal
zener in the level-shift part. It was amazingly noisy.

>
>
The "natural" CMRR and PSRR of a diff pair stinks without active loads,
at least on one of the rails; Thompson had to use tricks to get around
that to keep the output sitting at zero when the inputs were equal
>

I designed some little baby-board opamps, all TO-92 transistors and
folded-over axial parts. By selecting some resistors we got sub 1 mV
offset and under 1 uV/degC, but it was tedious.
 
I still have some Philbrick opamps that I found at a flea market.
 
https://www.dropbox.com/scl/fi/tujdcjpvv7m4b2yo8w751/Philbricks.jpg?rlkey=19ivv2tgqmqiy9ci92lgysrz7&raw=1
 

>
Are those the radioactive ones?

No, just 12AX7 dual triodes. The schematic can be found online.

The old Foothill Flea Market was great. Some old coot would die and
leave behind a garage of cool stuff and his kids would take it to the
flea market and practically give it away just to get rid of it.

The krytrons are radioactive.