4 Transistor FM Tracking Transmitter

The following diagram is the FM tracking transmitter based on 4 transistors. No additional notes for this tracking transmitter diagram, try to discover this circuit by yourself.. 🙂

4-transistor FM tracking transmitter

Components list:
R1 = 100K Ohms
R2 = 10 Ohms
R3 = 47K Ohms
R4 = 220 Ohms
C1 = 4.7uF/16V
C2, C5 = 1nF
C3 = 10 – 40 pF trimmer capacitor
C4 = 4.7pF

Q1 = 2N3906 PNP transistor
Q2, Q3, Q4 = 2N3904 NPN transistor
L1 = 4-5 turns of 22 ga. magnet wire close wound around 1/8″ non-conductive core
Antenna = 10 to 12″ hookup wire

With wide voltage supply (3-9v), this FM tracking transmitter can used 3V or 9V battery to operate.

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