Alastair Aitchison is an escape room designer. As such, he creates interactive puzzles that participants can solve to progress to the next stage of their quest. The challenge is that these puzzles need a rugged input, as they may take some abuse, and dealing with broken tech isn’t fun for anyone.
The typical solutions tend to be either: bland, in the case of industrial inputs; or a bit garish if you go with arcade buttons. Aitchison’s solution? Plumbing fixtures, of course!
Yes, plumbing (water) and electronics don’t generally mix well. Instead of liquid, however, he’s using these valves to regulate the passage of light through copper tubing. An LED is arranged on one side of the valve, while an LDR – linked to an analog input pin via a voltage divider – points toward the light source from the other side. As the valve opens, light hits the LDR and drops the resistance, causing a voltage proportional to the fixed and light-dependent resistor on the analog input.
It’s quite the clever setup, reminiscent of an opto-isolator that one can purchase in a very different format to isolate electrical signals. You can see more the details of the setup in the video, along with a demo of how it works with an Arduino. As noted, you’ll want to make sure your wires are properly insulated when using copper pipe, so that they don’t touch its conductive surface and cause a short circuit.