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 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.