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From: Gerhard Hoffmann <dk4xp@arcor.de>
Newsgroups: sci.electronics.design
Subject: Re: hobby electronics
Date: Wed, 3 Jul 2024 06:33:24 +0200
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Am 03.07.24 um 00:42 schrieb john larkin:

> I don't like protos with parts on one side and wires on the other. I
> can't see the connections. And once a proto is all hooked up, with
> power connections and cables and things, I don't want to flip it over
> to make changes.

 From subcircuits that have shown some value I tend to make stamp
sized boards, like the *10 *10 ADA4898-2 post amplifier at the right
in the ribbon preamp. My 1h laser printer to solder home etching
process helps.

> Haven't heard from H or H in ages.

  s.e.d. used to be a nice place back then!

> I need a microvolt precise unity-gain follower with nV and fA noise
> and low bias current, but no opamp like that exists, and jfets are too
> drifty.
> 
> AD8675 is about the closest I can find.

I have played with Bob Widlar's bipolar super-beta voltage follower.
It looks quite promising. Where else do you get gain = 1.000 just so?
Noise density is OK, too.
More transistors seem not to help any further.
More current, yes. Q4 and Q5 are just parking lots.

It would be interesting how a LM108 on today's hot processes would
look like.

< 
https://www.flickr.com/photos/137684711@N07/53830817262/in/dateposted-public/lightbox/ 
    >

I'm typing-challenged because I hurt my right shoulder yesterday :-(

cheers, Gerhard