This is the receiver for the previous transmitter. The microphone is of the high impedance ultrasonic type. The circuit activates a relay. The operational amplifier supports equivalent.
This circuit is from 1977 Radio Shack documentation. The circuit modulates an LED (which can be...
This setting appears multiple times on the site from different sources. This is from a 2000 manual...
This project was obtained in a 1982 documentation. The board consists of a labyrinth with trails...