This is a fun little prank I threw together last week at work. Here’s the back story: our group at work has a little game where we try to covertly hit the lever that raises/lowers the chair while the other guy is sitting in it. This is called “chairing” someone. I decided it was time to take it to the next level, so I made this little device to pull the lever under remote control.
The actuator is a little winch made from one of these awesome little geared motors I found on eBay. A plastic tube from a pen is the spool, and a frame made from music wire takes the force off of the gearbox bearing. The line is 30lb Spectra cord.
The control board is something I threw on my last PCB order as a space filler, with no specific plans for using it. It has an H-bridge, an 8-pin microcontroller, and a spot that fits a three-pin IR receiver. I populated it with a PIC12F615 and an IR receiver that was taken from one of my helicopters’ original control board. The whole thing was powered by a little lithium polymer foil pack.
The code is really simple, it just watches for a simple IR signal with a specific on/off time and then actuates the motor in one direction.
I quickly taped and zip-tied the pieces onto my coworker’s chair when he got up for a minute, and then dropped his chair with the remote while still sitting at my desk. Hilarious and worth it. I didn’t get a video of him getting pranked, but here’s a video of it actuating the lever:
Here’s the code for the receiver and the transmitter