Ultrasonic repellent 4011 (CB9385E)

This circuit was found in Radio Electronics from the 90s. The transducer is a tweeter and the power transistor must have a heatsink.

| Clique na imagem para ampliar |

Active inductor (CB20748E)
This circuit simulates an inductor. Or operational amplifier of old type, but a configuration is...
Logic Drive of the 7805 (CB25236E)
This circuit for the logic control of the 555 in a power supply was found in the October 1989...
Reed Relay Controlling a Triac (CB12184E)
This traditional configuration from a 1980 publication shows how a reed relay is used to control a 240...