Description

This is the circuit diagram of a radio transmitter suitable for fitting on radio collars.The circuit transmits a pulse in the FM between band 88MHz to 105Mhz , which can be adjusted.IC Ne 555 is wired as an astable multivibrator for producing the tone.L1 ,C3 and Q1 forms the modulator.Q2 performs the final power amplification.

Notes

For the inductor make 5 turns of .5 mm dia insulated copper wire on a standard ball pen refill.Remove the refill and make a tap at the center of coil.To vary transmission frequency experiment with number of turns.Carefull! what ever may be the no of turns the tap must be at center.Use a 50 Cm long insulated copper wire as antenna.

Parts List

R1…………………………………. 10K

R2 …………………………………1 M Ohm

R3 ………………………………….330 Ohm

R4 …………………………………..1 M Ohm

R5……………………………………. 330 Ohm

R6 ……………………………………200 Ohm POT

C1 ……………………………………..0.1 uF Ceramic

C2…………………………………….. 0.01 uF Ceramic

C3…………………………………….. 13 pF Ceramic

C4 ,C5, C6,C5 ……………………..0.01 uF Ceramic

Q1 ,Q2 ………………………………..2N4392 JFET

D1 ……………………………………….1N 914 Diode

IC 1……………………………………… NE 555

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