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.
We found this circuit of a transistor siren in a recent English publication. All components are still...
This two-input limit detector was found in an American 1980s documentation. The circuit can be...
This circuit was found in an old publicatio n from the year 1958. The circuit controls an external load by...