Wireless Microphone simple

 

  Wireless Microphone simple Parts list:

* T1,T2,T3: 2N2222 transistor
* R1: 10k 5%
* R2: 33k lin.
* R3: 12k 5%
* R4: 5.6k 5%
* R5: 2.2k 5%
* R6,R8: 47k 5%
* R7: 470 ohms 5%
* R9: 180 ohms 5%
* C1,C2: 47nF
* C3: 1nF
* C4: 33pF
* C5: 5.6pF
* C6: 8.2pF
* C7: 10nf
* L1: 3mm in diameter with 5 turns 0.61 mm copper wire
* K1: SPDT toggle switch
* Other parts: 2 AA battery holder, Electret microphone, antenna wire

Wireless FM microphone is simple to body and it has a advantageous transmitting ambit (over 300 meters in the accessible air). Despite its baby basic calculation and a 3V operating voltage it will calmly access over three floors of an accommodation building. It may be acquainted anywhere in the FM bandage (87-108MHz) and its transmissions can be best up on any accepted FM receiver.

The braid (L1) should be about 3mm in bore with 5 turns 0.61 mm chestnut wire. You can alter the Tx abundance by artlessly adjusting the agreement of the coils. The antenna should be a bisected or division amicableness continued (for 100 MHz 150 cm or 75 cm).

Circuit description:The audio addition date (T1) is a accepted accepted emitter amplifier. The 47nF capacitor isolates the microphone from the abject voltage of the transistor and alone allows AC signals to pass.

The LC catchbasin ambit is complete with T2, the acknowledgment capacitor C5 and the alongside LC ambit L1, C4. The coupling capacitor(C6) directs the arresting to the RF amplifier (T3).

Circuit calibration: Place the transmitter about 10 anxiety from a FM radio. Set the radio to about about 89 – 90 MHz. Spread the ambagious of the L1 braid afar to tune to the adapted frequency.