Analog Computer Progress Report (publ. 2025-01-31)

I continue to work on building up the analog computer, based on the Grappendorf schematics. Here is a photo of progress so far:

analog computer

analog computer (low resolution)

I have two integrators, one inverter, and one adder, though I haven't had time to test the adder yet. There are a few potentiometers on the bottom which will be used for coefficients, at least until I am able to mount some larger and better-quality potentiometers.

I am wanting to do this simple simulation from the Analog Thing docs:

Damped Oscillator

But I need one more inverter.

The Grappendorf files, which do not themselves come with any instructions or tutorials, do not make it clear what resistance value is recommended for the potentiometer, and I don't have experience myself to know what would be best. I figured I would try 5kΩ starting out and see how well that worked. I would think you would want the resistance value as low as possible, but if you go too low, you have a lot of current running through each of those resistors.

I've been looking around for some kind of analog computing community that does not require a facebook account or a Web browser, or anything like that doesn't conflict with my free software ideals. I couldn't find a mailing list, and there didn't seem to be any such channel on Libera IRC. There is ##electronics, of course, but I've found that half the users there don't even know what analog computing is, and any discussion requires lots of explanation.

So, I took a leap and registered my own channel on libera: #analogcomputing, with myself being the sole operator (and user) at present. If there is anyone else out there reading who has interest or expertise in analog computing, please drop in!

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