FM tracking transmitter based on 4 transistors

The picture below is an FM tracking transmitter based on 4 transistors. This trace transmitter diagram has no additional comments, try to discover this circuit yourself.

Component 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 22 ga. Magnet wire is tightly wound around a 1/8" non-conductive core

Antenna = 10 to 12” cable

This FM tracking transmitter is powered by a wide voltage (3-9v) and can be powered by 3V or 9V batteries.