This photoelectric sensor that triggers a relay was found in an English book from 1989. The transistor is a general-purpose type, and the integrated circuit consists of an operational amplifier.
We found this configuration in a 1974 technical documentation. It can test both TTL logic circuits and...
This circuit emits an alert sound (interval beeps) if the car lights are left on and the ignition key...
This is an amplifier that uses a pickup coil placed next to the telephone set and the listening is done in...