This circuit is from a 1976 amateur radio manual. The transistor can be the BD136 and the frequency adjustment is done in a potentiometer. The supply can be done with voltages from 6 to 15 V.
This complex circuit with many digital components measures inductances in 6 ranges ranging from 100...
This circuit triggers a photographic flash when the microphone picks up a sound. The SCR can be...
This simple MW radio circuit with two transistors was obtained in an Argentine publication from...