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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