I am going to do a completely silly project and build some logic gates using some 5 volt relays. The data sheet says the coil resistance is 130 ohms and 192 mW power. I think this means that roughly 38 mA of current will trigger the coil, which is pretty small.

These relays already have a fly back diode built into their coil, so no need there. But I want to use two diodes as inputs to create an OR gate, and use that to a relay inverter to create a NOR gate. Now if these were transistors I would use switching diodes for this purpose, but relays aren't transistors. However, 38 mA seems small enough that switching diodes would work here too.

Does my reasoning seem sound?

If anyone is curious, I want to build something like a relay counter and make a lot of noise while using the logic outputs to turn on some blinkenlights. Basically a really slow and noisy output device with a 50s retro-future vibe.

What a delightfully silly project! And yes, switching diodes should be fine, as they're generally rated for more current than that.

I like the counter idea. However, it might take some monkeying to make it work. To form each flip-flop, I'm imagining you'll have two relays cross-coupled to form a multivibrator, is that right? And there'll be some capacitors whose values need to be experimented with...

-- Jeff

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Thanks. Yes, some relay flip flops will form the basis for the counter. You're correct that some capacitors might be needed, but the whole thing is going to take some trial and error as relay logic isn't something I have done much of.