The frequency of this small transmitter, from a 1978 foreign publication, depends on the crystal. The range is 11 meters (citizen radio) and the coil will have 12 turns of wire 28 in a form of 1 cm without core. The microphone can be a small piezoelectric capsule, in which case the 330-ohm resistor can be omitted. The antenna is 1 to 2 meters long, and the transistor can be BC548 or BD135.
| Clique na imagem para ampliar |
