A: Higher frequency characteristics will be preferable. Solder the wires and the leads of the register. Give the wire 20-25 turns around the register. Prepare 4.7K ohm register (1/8 - 1/4 watt) and 0.2-0.5 mm coated wire. Different from the "simplest" model, unstable conditions of every section can cause problem of transmission and interference.Ī: Yes it is possible. If you want to use air coil, you must use a bit thcker wire like 1.0 mm and protect them from trembling that leads unstable frequency. Q: Do the coils have an air or ferrite core?Ī: Ferrite core. >See "How to supply the power" and the Diagram. Stabilizer for 12 vols (semiconductor) and the necessary capacitor (1000MF Electrolytic/25volts) But it is a compromise, though.Ĭoax Cable RG-62-u or RG-213 ->See "How to make a simple antenna?" In case you can't obtain this material, you can use "porous circuit board". Please note that for this work, you must have a frequency counter by all means.ġ Variable Capacitor (Vari-cap) Prepare a 5.0 mm diameter cylinderical material and enameled/polyurethane wire of 0.8-1.0 mm diameter. When you make coils by yourself->Diagramġ 8.5 Turns Molded Coil (5mm diameter bobbin)(inductance=ca.0.6-0.7MH)Ģ 3.5-4.5 Turns Molded Coil (5mm diameter bobbin)(inductance=ca.0.3MH) use of this transmitter with outdoor antenna is illegal in most parts of the world.1 27K 1/4 -1/8 Watt = (red-violet-orange)ġ 4.7K 1/4 -1/8 Watt = (yellow-violet-red) Note: This transmitter is meant only for educational purposes. They have 4, 6, 6, 5 and 7 turns of wire, respectively.
2 transistor fm transmitter install#
Install the antenna properly for maximum range.Ĭoils L1 through L5 are made with 20 SWG copper-enamelled wire wound over air-cores having 8mm diameter. Assemble the circuit on a general purpose PCB. You can also use a 12V battery to power the circuit. Regulator IC 78C09 provides stable 9V supply to the oscillator, so variation in the supply voltage will not affect the frequency generated. Also adjust trimmers VC2 through VC7 to get maximum output at maximum range. Carefully adjust trimmer VC1 connected across L1 to generate frequency within 88-108 MHz.
Use a heat-sink with transistor 2N3866 for heat dissipation ( Note: or 2N4427 because it works better at 12 V and delivers up to 1 watt RF power). Signals are finally fed to the class-C RF power amplifier, which delivers RF power to a 50-ohm horizontal dipole or ground plane antenna.
2 transistor fm transmitter driver#
The preamplifier is a tuned class-A RF amplifier and the driver is a class-C amplifier. You can also use transistor 2N5109 in place of 2N2219. The FM signals are amplified by the VHF preamplifier and the pre-driver stage. When you speak near the microphone, frequency-modulated signals are obtained at the collector of oscillator transistor T1. Working of the 1 Watt transmitter circuit is simple. This FM transmitter circuit uses four radio frequency stages: a VHF oscillator built around transistor BF494 (T1), a preamplifier built around transistor BF200 (T2), a driver built around transistor 2N2219 (T3) and a power amplifier built around transistor 2N3866 (T4).Ī condenser microphone is connected at the input of the oscillator.
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