What’s one to do with some good little relays of questionable pinout, and prototyping board? How about a quietly clicky 4-bit counter utilizing relay logic with tons of buttons?
[Agatha Mallett] made the counter after discovering herself in possession of a amount of relays burdened by horrible documentation (the datasheet shockingly lacks a pinout, and doesn’t even point out the coil being unidirectional). However for the reason that relays are additionally small and of respectable high quality, they had been an excellent candidate for a small relay logic-based mission.
The important thing to the construct is implementing D-type flip-flops utilizing relays. That is completed by holding the coil voltage of every relay between its set and launch voltage ranges. A small voltage bump will energize the coil, closing the relay and leaving it closed. Conversely, a small unfavorable spike releases the coil, leaving it open. This types the premise of the counter, and [Agatha] has a separate write-up all concerning the particulars of utilizing relays on this manner.
Implementing this was moderately much less simple than it could sound as a result of it depends on balancing the coils of many relays on a figurative knife-edge of voltage, however not each element is completely an identical. A tweaked resistor or capacitor right here and there was wanted earlier than issues settled into reliability.
The tip product has indicator LEDs, buttons to increment or clear the present rely, and it even has buttons to set or clear particular person bits. This can be a mission that begs to be interacted with, and there’s a brief video on the mission web page so you possibly can watch it undergo its paces.
Due to [Jess] for the tip!
