Circuit Description

The circuit diagram of Radio Collar Transmitter has been described here. This circuit is based on the IC NE 555 which is the central part of this circuit. In this circuit the IC NE 555 plays the role of astable multivibrator which produces the tone. Basically this circuit is FM transmitter which transmits pulse in a frequency band of 88MHz to 105MHz. This frequency range is adjustable. Transistor Q1 and associated circuitry consisting of L1 and C3 perform the job of modulation. Transistor Q3 is used for power amplification at the final stage of the circuit.

Components List

  • Resistors: R1 (10K), R2 (1 M Ohm), R3 (330 Ohm), R4 (1 M Ohm), R5 (330 Ohm), R6 (200 Ohm POT)
  • Capacitors: C1 (0.1 uF), C2 (0.01 uF), C3 (13 pF), C4, C5, C6, C5 (0.01 uF)
  • Transistors: Q1, Q2 (2N4392 JFET)
  • Diode: D1 (1N 914)
  • IC: NE 555

Circuit Diagram

Radio Collar Transmitter Circuit

Radio Collar Transmitter Circuit


  • Use a good quality PCB to assemble this circuit.
  • 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.
  • Use a 50 Cm long insulated copper wire as antenna.