Minivac 601 Simulator - a 1961 Relay Computer
Hey HN! I'm very proud of sharing this project with you all, after ~2 years of starts and stops, and about 5 different attempts at making it. Context/history: In 1961, the Minivac 601 [0], an educational electronics kit - somewhat similar to those "300 circuits in one" you may have had growing up as I did - was created by none other than Claude Shannon. The Minivac is disarmingly simple: it consists roughly speaking of 6 relays, 12 lights, 6 buttons, and a motorized wheel. You'd think that it couldn't really do much. Well, amazingly, it can do a lot. You can wire up the components in a…
In plain words
The Minivac 601 Simulator is a digital recreation of Claude Shannon's 1961 educational electronics kit, which used relays, lights, buttons, and a motorized wheel to perform computing tasks. The simulator allows users to wire up components to build functional circuits, such as binary counters, tic-tac-toe players, and digit recognition systems. It is designed for educators, hobbyists, and anyone interested in understanding how simple relay-based systems can accomplish complex computational tasks, drawing inspiration from Shannon's original manuals.
written from the facts on this page · September 2026
From the sources
In the maker’s words, at launch
Hey HN! I'm very proud of sharing this project with you all, after ~2 years of starts and stops, and about 5 different attempts at making it. Context/history: In 1961, the Minivac 601 [0], an educational electronics kit - somewhat similar to those "300 circuits in one" you may have had growing up as I did - was created by none other than Claude Shannon. The Minivac is disarmingly simple: it consists roughly speaking of 6 relays, 12 lights, 6 buttons, and a motorized wheel. You'd think that it couldn't really do much. Well, amazingly, it can do a lot. You can wire up the components in a way that will make the Minivac play tic-tac-toe, or OCR-detect 10 digits... The sample "demo" circuit I chose for the homepage shows a binary counter that counts up to 7. Another amazing thing about the Minivac is definitely its manuals [1]. Their spirit is what I hope to capture in the coming (years?) as I keep improving this project. The manuals are generous and well-written and are not only an amazing gradual introduction to relay-based logic - they touch on computing at large. With amazing 1960s graphics/cartoons, of course. That's probably what got me to work on the Minivac. I learned about the device a bit before going to the Recurse Center, fell in love with the manuals, and was frustrated that I couldn't try out the circuits or play around with the device! I thought that creating a JavaScript-based emulator would be an "easy" way to get there. Turns out that correctly simulating electricity isn't "easy". :-) But I'm very proud that it now seems to be doing the right thing for most circuits that I've tested from the book. Yes, this Minivac Simulator has a TypeScript testing suite! Looking forward to hearing from you all. Cheers [0] https://en.wikipedia.org/wiki/Minivac_601 [1] https://minivac.greg.technology/manuals/1961-minivac601-book... Repo: https://github.com/gregsadetsky/minivac/
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