Single chip FM transmitter
An FM transmitter is a device that can transmit audio from an audio device as a radio signal. Doing so allows the audio to be picked up and played by an FM radio in the transmitter’s range. The FM (frequency modulation) device allows the waves to move in predefined frequencies so it can be identified by a radio tuned o this particular frequency range.
FM transmitters can be made in different ways. Circuitstoday alone has at least 5-6 articles dedicated to constructing these transistors.
Here is another method of building an FM transmitter, this one uses an IC.
Here’s a single chip FM transmitter circuit using Maxim semiconductors IC MAX2606.
The MAX2606 is a compact, high-performance intermediate frequency VCO specially designed for wireless communication circuits. They have monolithic construction with low-noise and a low-power operation in a compact 6-pin SOT23 packing.
This low-noise IC features an on-chip varicap diode and feedback capacitances that avoid the need for external tuning components, making the MAX2606 perfect for portable systems. Only an external inductor is needed to set the oscillation frequency. In addition to this, an integrated differential output buffer is also there for driving a mixer or prescaler.
The MAX2606 can be operated from a single +2.8 V to +5.4V supply and consumes very less current. The chip can be operated from 45MHz to 650MHz.
In the circuit, the nominal frequency is set to 100 Mhz by inductor L1, (390nH). The left and right channel audio signals from your source are added by R3 and R4, and attenuated by the POT R2. R2 can be used as a volume control. POT R1 can be used to select a channel of transmission between 88Mhz and 108Mhz. Use the 80 cm long wire as the antenna.
FM Transmitter Circuit Diagram with Parts List.
- Assemble the circuit on a good quality PCB or common board.
- Use a battery for powering the circuit. It will reduce noise.
- An FM antenna from an old radio is a better option than the wire antenna.
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