Friday, May 13, 2011
Wireless FM Transmitter
The wireless transmitter ambit congenital about transistor T1 (BF494) is a basal low-power variable-frequency VHF oscillator. A varicap diode ambit is included to change the abundance of the fm transmitter and to accommodate abundance accentuation by audio signals. The achievement of the oscillator is about 50 milliwatts. Transistor T2 (2N3866) forms a VHF-class A ability amplifier. It boosts the oscillator signals’ ability four to bristles times. Thus, 200-250 milliwatts of ability is generated at the beneficiary of transistor T2.
For bigger results, accumulate the ambit on a good-quality bottle adhesive lath and abode the transmitter central an aluminium case. Shield the oscillator date application an aluminium sheet.
Coil ambagious capacity are accustomed below:
- L1 – 4 turns of 20 SWG wire close wound over 8mm diameter plastic former.
- L2 – 2 turns of 24 SWG wire near top end of L1.
- (Note: No core (i.e. air core) is used for the above coils)
- L3 – 7 turns of 24 SWG wire close wound with 4mm diameter air core.
- L4 – 7 turns of 24 SWG wire-wound on a ferrite bead (as choke)
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