What is a High Range FM Transmitter?
An FM Transmitter is an electronic device that can air audio signals from a source on a selected range of frequencies. They are generally used to broadcast stationary audio from devices such as TV & computers, around a room. They are inexpensive & simple to design. So, in today's article, we will look into a step-by-step tutorial on how to make a High Range FM Transmitter circuit using some NPN transistors & a small no. of other components.
Whatever may be the schematic scope or design, every FM transmitter is based on the same three key stages: Audio pre-amplification, Modulation and, transmission. The first stage generally consists of amplifying & filtering an input audio signal. In the second stage, the input audio signal is modulated and a carrier signal is generated by a variable frequency oscillator circuit. In the last stage, the modulated audio signal is transmitted using an antenna between the FM frequency range of 88MHz to 108MHz.
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You will need the following parts to build this project.
|1)||FM Transmitter PCB||-||1|
|5)||Capacitor||0.1uF, 0.01uF, 4.7pF||3|
|6)||Enameled copper wire||18 AWG||1.5ft|
|7)||Resistor||1M, 100K, 10K, 1K, 100 Ohm||7|
|8)||Soldering Iron||45W - 65W||1|
|9)||Soldering Wire with Flux||-||1|
|12)||Jumper Wires||-||As per need|
The working of this circuit is pretty simple, an input audio signal from a device such as a smartphone is taken through an electret mic. Here, a coupling capacitor of 0.1uF is used to block the DC component of the signal, allowing only AC to flow. This signal acts as a control signal to the base of the 2n3904 transistor (Q1).