We found this circuit in the magazine Eletcronics Now of July 1994. The power supply is according to the relay and the transistor can be any general purpose one.
This circuit is designed to activate an automotive alarm after 8 minutes of activation. Of course...
The coils determine the frequency of this oscillator that we found in the January 1996 issue of...
This simple timer can be used in many applications such as egg timer. The LED glows up when S1 is...