This circuit emits a signal in the AM range, whose modulation frequency depends on the intensity of the light that falls on the LDR. The transistors can be old PNP germanium or modern types such as BC558 and the power can be between 6 and 9 V, The oscillating coil has a primary of 50 + 50 turns and a secondary of 30 turns of wire 28 to 30 in ferrite rod. The variable can be obtained from an old medium wave radio and the modulator transformer is an old transistor radio driver or output.
| Clique na imagem para ampliar |
