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From: Christopher Howard <christopher@librehacker.com>
Newsgroups: sci.electronics.design
Subject: Re: signal leads that pick up less ambient noise?
Date: Thu, 20 Feb 2025 13:41:02 -0900
Organization: A noiseless patient Spider
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>
> If you make your signals balanced differential drive then you can
> withstand a lot of ambient common mode noise without problems. The way
> that instrumentation amplifiers do it.
>

I'm interested in this idea, though I'm not sure how to apply this in
any practical way to the connections inside the analog computer, i.e.,
the patches between the different integrators and such.

As far as the connection from the signal generator to the analog
computer input, that doesn't sound too hard. But with a quick search on
the Internet, it seems that balanced cables are not made with BNC
connectors on one end, to match the signal generator. Do you know of an
adapter that would work for this?

For the differential receiver, do I need anything special for this, or
can I just feed the conductors into an LF356 op amp (unity gain
configuration...?)

>
> IOW rather than coax you have two signal lines v+ and v- inside a
> passive conductive outer shield that plays no part in the signal
> transmission. It is there only as a Faraday shield against external
> interference.
>

Any particular cable you recommend?

> I think there is something funny going on with your setup.

I don't know of anything "funny" but am still learning. This is
certainly a DIY, learn-as-you-go project. For the analog computer, I'm
largely following the Grappendorf schematics, though building it on a
breadboard instead of printing the PCBs, which I can't afford right now.

https://www.grappendorf.net/projects/analog-computer/

Some other substitutions I have made: I haven't built a PS as I happen
to have access to a bipolar 15V supply already, though admittedly it is
a rather old unit. I also haven't built the reference voltage module but
am hoping to have parts for that in the next few weeks.

-- 
Christopher Howard