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.
In the figure we show how to use a 555 to control an SCR or another type of thyristor. Resistors R1, R2...
This circuit activates one of the selected circuits with a touch of a switch, keeping it...
This powerful FM transmitter was found in 1992 documentation. The circuit requires a 12 V source...