This shortwave telegraph transmitter can send its signals to a receiver a few tens of meters away. L1 depends on the range and can have 10 + 10 to 20 + 20 turns of wire 28 in a ferrite rod for the range of 5 to 15MHz. CV is a variable capacitor of AM radio and the antenna can be from 50 cm to 2 meters long. The supply can be done with voltages from 6 to 9V. For 12V use a BD135 transistor. Capacitors must be ceramic.
