There used to be a commercially-made tv-b-gone device. Not sure if it's made anymore, but there's a DIY kit that appears to do the same thing: https://www.adafruit.com/product/73

I used to carry one with me everywhere (it was small enough to fit on a keychain). One night at a sports bar, I showed it to a friend. Before I could stop him, he pushed the button and every TV in the place went black, right in the middle of some PPV sports event. Anyway, he bought one on the spot.

There was a guy who sold a chip for that which you fitted to a car keyfob. In the olden days of the late 80s, Valeo used a pretty insecure not-rolling-code infrared thing for central locking systems.

Anyway you'd get a handful of old Rover, Peugeot, Renault, or Citroën (and a bunch of others) fobs from the scrapyard and fit this pre-programmed PIC microcontroller, and when you pressed the button it would cycle through a bunch of volume down, mute, and power off commands for most common brands of TV.

However the real genius one - and it was about 20 quid - was this. Remember Furbies? They would chatter away to each other, using infrared to communicate so they'd go in sync. Well, this one that transmitted the "GO TO SLEEP RIGHT NOW" command to any Furby in the room. Relatively expensive but worth it.

When iPhones still had the headphone port, a friend of mine soldered a IR led on top of a minijack, something like this:

https://www.rtfms.com/wp-content/rtfms-com/LED-pinout.png

Then, with some special app, or even just playing some audiofiles — I don't remember — he'd do the same thing as the device above.

Wow, this is clever. Yeah, the headphone out can push out a signal like 1 volt at low current, but this is likely enough for the IR LED to "light up". I really like this idea.

> There used to be a commercially-made tv-b-gone device.

Not sure about that one either but its functionality has been cloned for the Flipper Zero [1]

[1] https://blog.flipper.net/infrared/

The original TV-B-Gone [0][1] was designed by the legendary Mitch Altman [2].

[0] https://en.wikipedia.org/wiki/TV-B-Gone

[1] https://www.tvbgone.com/

[2] https://en.wikipedia.org/wiki/Mitch_Altman

The Woz would be so proud

There’s a TV-BE-GONE app for Bruce on the CardPuter and I think one for the Flipper Zero as wells. It will cycle through dozens of codes to power off the TV. It’s been fun to turn off random TVs, though I don’t do it much because I don’t want to be too much of a douche.