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Minivac 601 Simulator

a 1961 Relay Computer

Details

External ID
45945762
Source
HN
Company
—
Product
Minivac 601 Simulator
Website domain
greg.technology
Launched
Nov. 16, 2025
Cohort
—
Upvotes
21
Upvotes percentile
0.7030567685589519
Tags
—
Fetched at
Sept. 7, 2026, 9:25 p.m.
Updated at
Sept. 7, 2026, 9:25 p.m.

Description

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/

Enrichment

Theme
interactive simulations and creative experiments
Vertical
Horizontal
Function
Hardware & robotics
Audience
Prosumer
AI stance
Not AI
Project type
Hobby / open-source project
Normalized one-liner
simulator for vintage relay computer
Manually corrected
False

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 — 89 launches clear the similarity bar, closest 8 shown.

Attention rank: #40 of 90 (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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