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Comment by gregsadetsky | Hacker News Reader

Thank you so much everyone, this is something I've worked on for a few years on and off -- I posted about it here in a Show HN a few hours ago [0]

The biggest unlock was finding Willy McAllister's excellent Circuit Sandbox [1], which provides the Minivac Simulator's underlying electrical math. I tried so many approaches to simulate electricity (a doomed DIY approach, Falstad, Spice...) but Circuit Sandbox's DC analysis did the job perfectly.

Ping me for questions, and would love to read your feedback!

[0] https://news.ycombinator.com/item?id=45945762

[1] https://spinningnumbers.org/a/circuit-sandbox.html

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Thanks for making this! Love the manuals too. It reminds me of the Radio Shack 150-in-one electronics kit I had as a kid.

Super cool. And thanks for links to the original manuals for those that want to take a deep dive.

Feature request: I was wanting for a bit more sound… I mean, when I see "relay computer", I'm heading there for lots of soft clicks.

More…?! :)

I totally feel you - the one reservation is that I’m using (gasp) not the original Minivac Relay sound. I need to go to a Computer Museum that will let me record one to offer a more authentic simulated experience.

So tldr - let me get a clean real sound and then we can come back to this question :)

I heard some clicks. I thought they were just the sounds of the switches I was toggling. Are there other (relay) sounds I somehow missed?

Just to make sure I'm not misunderstanding:

The relay click sound you're hearing should only happen when a relay turns on, and when it turns off. There is no sound when a button is pressed - you can check this by loading an empty simulator and pressing any of the buttons at the bottom (the simulator won't make any sound):

https://minivac.greg.technology/simulator/

((Once/if I get to see a Minivac in real life, I may learn that buttons do make sounds..))

When a relay turns on and off, a sound is played. In the following circuit, check this by pressing and releasing the button 1:

https://minivac.greg.technology/simulator/#wires=1%2B%2F1C%2...

You may not need to get a museum's cooperation. After a quick search it seems these come up for sale from time to time. I saw one on the Vintage Computer Federation forums offered in 2021 for $500. You may be able to find a collector online who has one and will record the relays for you. A lot of folks have pretty high-quality USB mics for conferencing/podcasting these days.

An alternative might be going to a regional VCF show where one will be (possibly by pre-arrangement with a collector). There are five or six shows held around the country every year. Unlike a museum almost all the devices there are available for hands-on interaction.

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