The VU Meter (audio controlled lighting)
For our production of One Third of a Nation, we had a character called the Loudspeaker who's voice needed to come in through a microphone, be pumped out of two speakers above the audience, and also control the pulsing of the light in the VU meter sitting next to her on the desk. The complication was that I needed to give the LD control over the VU meter light so she could produce true blackouts. By routing the mic signal through a MAX/MSP patch that translated the mic level into a variable number inserted into a continuously outputting MSC message, I created a direct relationship between the mic's volume and the level of a submaster on the lighting console. The resulting effect was a VU meter that pulsed to the Loudspeaker's lines while allowing the LD to fade it out when it came time for a blackout.
Before Qlab 3 came out, and subsequent Qlab Remote for iOS, I built a Qbox using a scavenged interface from a USB keyboard, a project enclosure, and LED arcade buttons. I stole power from the USB for the LEDs and hardwired the buttons to the interface in place of the keyboard's key contacts. It worked great, though eventually the LEDs started to fade and I realize now that I should have added in-line resistors for each LED.
We did a show where a character was supposed to reach outside the barn door and catch a firefly. He then has a conversation with another character while we see the glow of the firefly emanating from his hands. I bought a small PCB board from Radio Shack and put a force sensitive resistor between a tiny 12v battery and an LED. I added a couple smaller resistors to be safe, as well as an off switch so I was sure there was no energy leak. Hot glue the right color gel over the LED and now you have a firefly whose pulsing can be controlled by how hard/fast you compress the FSR. Measures about 2"x1"x0.5".
This was a piece I created for my wife to walk down the aisle to. I really wanted to put together something original to be incorporated into the ceremony. She loved it.