We found this circuit in the May 1996 Electronics Now magazine. The relay must have a voltage according to the circuit power supply and a trigger current of no more than 50 mA.
This digital CMOS circuit generates sinusoidal signals from a 10 kHz rectangular signal. The...
Found in an 80's Elektor, this circuit can use any equivalent optical coupler. The buzzer is of the...
Found in a 1965 Electronic Design, this circuit limits surges in a load when power is applied. The...