TV and FM jammer schematic
The Jammer is a very small circuit and can fit inside a small plastic box with 9V battery inside. It can be very illegal if you attach an external antenna so don't. adjust frequency by turning trimmer. It is intended only as a practical joke device. The Capacitor is 6-10pf air capacitor and the transistor used here is the 2n2222.
UPDATE: There is an new improved version of this jammer at the following link:
Datasheet file1: Click here to download 2N2222.pdf datasheet.