Relay Computer Starts with an Adder that Makes a Racket

Computers built using discrete logic chips? Seen it. Computers from individual transistors? Impressive, but it’s been done. A computer built out of electromechanical relays? Bring on the ozone!

The aptly named [Clickity Clack]’s new YouTube channel promises to be very interesting if he can actually pull off a working computer using nothing but relays. But even if he doesn’t get beyond the three videos in the playlist already, the channel is definitely worth checking out. We’ve never seen a simpler, clearer explanation of binary logic, and [Clickity Clack]’s relay version of the basic logic gates is a great introduction to the concepts.

Using custom PCBs hosting banks of DPDT relays, he progresses from the basic AND and XOR gates to half adders and full adders, explaining how carry in and carry out works. Everything is modular, so four of his 4-bit adder cards eventually get together to form a 16-bit adder, which we assume will be used to build out a very noisy yet entertaining ALU. We’re looking forward to that and relay implementations of the flip-flops and other elements he’ll need for a full computer.

And pay no mind to our earlier dismissal of non-traditional computer projects. It’s worth checking out this discrete 7400 logic computer and this all-transistor build. They’re impressive too in their own way, if a bit quieter than [Clickety Clack]’s project.

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NES controller gets a rumble pak

Add some feedback to an original NES controller by making it vibrate. This feature is often known as Rumble Pak, a controller add-on for the Nintendo 64 which vibrated as a game feature. This version adds a small DC motor (in the upper right) with a screw soldered off-center to the motor shaft.

[Andy Goetz] and his friend built this as a robot controller, taking advantage of the latch and clock pins. Normally, nothing happens while both pins are held high, a signal that they easily patched into using an AND gate. This is actually a neat find, as the addition of an internal microcontroller could add bi-directional communication when the latch is high and the clock is strobed.