This circuit is from an 80's technical newsletter. The circuit can use any general purpose transistor and its power supply can be changed with a resistive divider to use a single 9V battery.
This circuit, which can also be adapted to function as a microcontroller shield, is from 2003...
This sensitive circuit was found in an Electronics Hobbyists Handbook from the 1990s. The circuit can...
This circuit can be used with 3 receivers and is intended for low frequencies (medium wave range). We...