This circuit is from the 1989 special edition of Radio Electronics Experimenter. The circuit was created with SMD components to be mounted on a keychain.
We found this circuit on Radio Electronics from July 1990. It triggers a relay with a touch of the...
This medium wave radio works with any general purpose NPN transistor. The diode must be made of...
The frequency of this oscillator depends on the crystal used and the transistors. The circuit was...