Wireless FM Transmitter

Wireless FM Transmitter Circuit Diagram

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)

Potentiometer VR1 is acclimated to alter the axiological abundance admitting potentiometer VR2 is acclimated as ability control. For hum-free operation, accomplish the wireless fm transmitter on a 12V rechargeable array backpack of 10 x 1.2-volt Ni-Cd cells. Transistor T2 charge be army on a calefaction sink. Do not about-face on the transmitter after a analogous antenna. Adjust both trimmers (VC1 and VC2) for best manual power. Adjust potentiometer VR1 to set the axiological abundance abreast 100 MHz.