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Minivac 601 Simulator

a 1961 Relay Computer

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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/

HN · launched Nov 16, 2025 · 21 upvotes (top 30%) · 0 views

Niche: scientific and system simulation software · 74 launches, 2 in the last 7 days · Explore this niche →

Category and tags

  • Education
  • Hardware & robotics
  • Prosumer
  • Not AI
  • Hobby / open-source project

Visit website ↗ Source listing ↗

Could you build this?

Partial A web UI is easy to produce, but accurately modeling 1960s electromechanical relay logic, switch states, and non-ideal circuit behaviors requires specialized hardware and circuit simulation modeling.

What it would actually take: The stack comprises a canvas/WebGL interactive frontend mimicking the 1961 physical console and an underlying cycle-accurate circuit simulator engine in JavaScript/TypeScript. The hard part is modeling electrical relay dynamics, voltage loops, mechanical contacts, and transient states authentically rather than treating the machine as pure abstract Boolean logic.

Discussion

1 comment analyzed.

Competitors

Other products that read as similar to this one : 191 launches clear the similarity bar, closest 8 shown.

Attention rank: #74 of 192 (itself plus its competitors, highest first, normalized so YC and Product Hunt are compared fairly).

Launched 16 days after the earliest competitor.

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