The world's simplest radio jammer
The other day at verk one of the guys in a neighbouring building had his radio up so loud that I could hear it through our thick concrete walls. Since I don't particularly care to hear all 3 hours of Rush Limbaugh's show while trying to download porn while pretending to work, something had to be done. So I cooked up an FM jammer and farted my blues away.
This is the simplest jammer possible. All it is is a 100Mhz crystal oscillator with an antenna stuck on it. 100Mhz oscillators are pretty damn rare, but I managed to find one on some old circuit board from the 90s and desoldered it. I hooked up power as shown, and stuck on an antenna made from a thin piece of wire. The antenna was about 80cm long.
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So yeah a crystal hooked up to a piece of wire will silence a radio for a surprisingly good distance, and through thick walls. The interesting thing is that although it is supposed to be a crystal accurate to 100.000etc Mhz it blanked out the entire FM band!
Btw this is illegal to do so don't do it. I didn't.
Update: People keep saying a lot of crap about this thing. This oscillator does NOT put out a square wave. It works by the fact that most cheap radios will have inadequate bandpass filtering on their front end, so the 100Mhz signal swamps stuff out. Most people find a brand new oscillator will only blank out 98-102Mhz. My oscillator was taken from a 486DX4-100 motherboard. Other people have had some success finding similar oscillators and trying this on the Hackaday comments thread. Not every oscillator will have the same pinout as the one I had.