This circuit was found in an Electronic Design. It makes use of a relaxation oscillator to trigger an SCR and two relays. The circuit operates at frequencies of 12 to 180 cycles per minute.
We find this circuit in a 1973 technical documentation. Common transistors may be BC548 and FET or...
We found this circuit in a 90's Popular Electronics. The circuit produces a loud sound if S2 is...
This circuit from General Electric was found in a 1967 documentation. The SCR is of the time, as...