This is a rather simple, match-the-words switchboard style of puzzle. It has 6 vacuum tubes…. the old ones from the Cosmos rebuild actually… which light up every time you get a combination correct.

The puzzle is made out of Batu timber, with an MDF switchboard plate and a piece of poly-carbonate in front of the valves. An inordinate amount of impulse-purchased ALDI tools are now present in my workshop.

It was just a matter of tediously attaching all of the 1/4 inch jacks, hot glue the valves in place with LED’s underneath, and wire everything up to the Arduino.

The trick is to invert the connections in the patch wires, so that the tip of one wire connects to the shield on the opposite end. Then it is simply a matter of connecting the shield connection of the destination jack to the Arduino, and the tip of the origin jack to the Arduino.

The program is very simple, it simply sequentially energises every output pin, while reading the corresponding input logic state. If the inputs and outputs match, it energises the LED, when all the connections are correct, the relay triggers. A small header board with resistors for the LED’s seemed like a fun thing to do at the time.

I even designed this thing in CAD before making it, just because.