The resistors R1 and R2 consist of 8 220 ohms x 2 W resistors connected in parallel. The dissipation must be higher for high transmitter power. The indicator can be the multimeter.
In the original version of this 1987 circuit, the loads are lamps, but it can be adapted to drive a...
This circuit is suggested by Motorola, using a 4N26 type coupler and an MC1733 type operative. However,...
This TTL oscillator uses an old TV crystal, having been found in an American publication in 1976....