Hackaday Prize Entries: Inventing New Logic Families


One of the favorite pastimes of electronics hobbyists is clock making. Clocks are a simple enough concept with a well-defined goal, but it’s the implementation that matters. If you want to build a clock powered only by tubes and mains voltage, that’s a great skill tester. A relay-based timepiece is equally cool, and everyone should build a Nixie tube clock once in their lives.

For [Ted]’s Hackaday Prize entry, he’s building a clock. Usually, this would be little cause for celebration, but this is not like any clock you’ve ever seen. [Ted] is building this clock using only diodes, and he’s inventing new logic families to do it.

Using diodes as logic elements has been around since the first computers, but these computers had a few transistors thrown in. While it is possible to make AND and OR gates using only diodes, a universal logic gate – NANDs and NORs – are impossible. For the computers of the 1950s, that means tubes or transistors and DTL logic.

For the past few years, [Ted] has been working on a diode-only logic family, and it appears he’s solved the problem. The new logic family includes a NOR gate constructed using only diodes, resistors, and inductors. The key design feature of these gates is a single diode to switch an RF power supply on and off. It relies on an undocumented property of the diodes, but it does work.

Although [Ted] can create a NOR gate without transistors — a feat never before documented in the history of electronics — that doesn’t mean this is a useful alternative to transistor logic. The fan-out of the gates is terrible, the clock uses about 60 Watts, and the gates require an AC power supply. While it is theoretically possible to build a computer out of these gates, it’s doubtful if anyone has the patience to do so. It’s more of a curiosity, but it is a demonstration of one of the most mind-bending projects we’ve ever seen.

You can check out a video of the diode clock below.


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