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 fact, this dimmer can be used with currents up to 1.5 A according to the General Electric...
This circuit was found in a 90s Radio Electronics. It is intended to amplify the sound channel of...
This circuit has the intensity of the signals controlled by the light that falls on the sensor....