A device you can keep pointed at your TV to prevent others from using a remote to change the channel, the volume, and so forth. (When you want to use the remote, turn it off. Turn it back on when you’re done.)
The copy from the board:
This is a device that flashes IR LEDs at 38kHz, the same as the signal timing of most TV remotes. Keep it pointed at the TV to “trick” it into not allowing others to change channel, volume, et c. (by remote, anyway). The device is tuned by adjusting the 10k trimmer through some trial and error, but in general this is a one-time adjustment.
This is Kip Kay’s version with some minor notational adjustments. Various others are available, and all is subject to hacking.
Actually, this is just the 555 astable circuit played perfectly straight, with a couple of IR LEDs driven by the output.
You could really put all sorts of other things on that output and the circuit would still work. I’m certain, for example, that it would be possible to make a version that uses an NPN transistor (I have way more of the NPN 2N2222 than of the PNP 2N3906) and omits the diodes in favor of some well-placed resistors (the diodes here seem to be used for their 1V drop rather than their directional property).
Aren’t 555s handy?