In this circuit the triac conducts when switch S1 is opened. We found it in the October 1987 Radio Electronics magazine. The triac is controlled according to the load.
This circuit can be used in PLL, frequency synthesizer in FM and VHF receivers, reducing a...
We found this circuit in an old documentation. Transistor can be BC548 and relay according to...
This is a typical 3 ½ digit TTL counter. We found it in the September 1973 issue of Radio...