- Here, uses FM modulation for sound and PAL for video modulation.
- The audio signal to be modulated is pre-amplified using the transistor Q1 and associated components.
- The transistor Q2 has two jobs: production of carrier frequency and modulation.
- The pre-amplified audio signal is fed to the base of transistor Q2 for modulation. Capacitor C5 and inductor L1 forms the tank circuit which is responsible for producing the carrier frequency.
- The video signal is fed to the emitter of transistor Q2 via POT R7 for modulation. The modulated composite signal (audio+video) is transmitted by the antenna A1.
- NOTES:
- Assemble the circuit on a good quality PCB.
- Inductor L1 can be made by making 4 turns of 24SWG enameled copper wire on a 6mm dia: plastic former.
- T1 can be a radio frequency transformer with built in capacitor. (Can be found on old transistor radio boards).
- Antenna A1 can be a 1M long copper wire. (Experiment with the length to get optimum performance).
- This transmitter is working in VHF band somewhat between 50 – 210MHz.
- This transmitter is compatible only with PAL B and PAL G systems.
