This circuit is from General Electric from the 80s, using a relay with high current contacts (20 A). The transistor admits equivalent, and any phototransistor can be used as a sensor.
The operational Amplifier used in this circuit is uncommon today. However, the same circuit can be...
This small blocking oscillator for approximately 1000 Hz was found in an American documentation from the...
We found this circuit in a Radio & Electronics Constructor from November 1975. The magazine no longer...