We found this circuit in a 1991 Hobbyst Electronics. The circuit makes use of an unusual transducer today. It is a piezoelectric buzzer that can eventually be replaced by an equivalent configuration.
Found in an Electronic Design from the 90's, this circuit uses common components. The circuit is...
When the sensor receives light, the relay closes its contacts and remains so even after the light...
This circuit produces pulses of 90 V at intervals that can reach 5 minutes. The circuit is from a...