FM Transmitter Circuit with 10Watts+ Output Power and 10km Long Range
Powerful FM Transmitter Circuit with 10Watts+ Output Power and 10km Long Range
FM Transmitter Full Circuit Diagram
FM Transmitter Circuit with 10Watts+ Output Power and 10km Long Range electrobuff.blogspot.com
Here's a simplified explanation of how an FM transmitter works:
LM7809 IC
This is a linear voltage regulator IC. It provides regulated, low noise (unlike switching regulators) voltage supply of 9 Volts from a power source of 11 to 35 volts to power the critical oscillator circuitry.
Electret Microphone:
The process begins with the electret microphone, which converts sound (audio signals) into electrical signals. These electrical signals are typically very weak and need to be amplified for transmission.Pre-Amplifier:
The pre-amplifier takes the weak electrical signal from the microphone and boosts its strength. This amplification is necessary to ensure that the signal is strong enough to be modulated onto a radio frequency carrier wave.
Radio Frequency Oscillator:
The radio frequency oscillator generates a carrier wave at a specific frequency. For FM (Frequency Modulation), this oscillator produces a stable radio frequency signal that will carry the audio signal from the microphone. The oscillator is a classical L-C circuit with a frequency dependent on the value of the capacitor and inductor connected in parallel to each other.Modulation (Frequency Modulation):
In FM transmission, the audio signal (now amplified) modulates the frequency of the carrier wave. This means the frequency of the carrier wave varies slightly in accordance with the audio signal. Stronger audio signals cause greater frequency variations.Power Amplifier:
The modulated signal (now containing both the carrier wave and the audio signal) is sent to the power amplifier. The power amplifier increases the power of the signal to a level sufficient to drive the antenna.Antenna:
The antenna radiates the amplified signal into space as radio waves. These radio waves carry the modulated audio signal to receivers within the transmitter's range.Working Principle:
Signal Generation: The electret microphone picks up sound waves and converts them into electrical signals.
Signal Amplification: The pre-amplifier boosts the weak electrical signals from the microphone to a stronger level suitable for modulation.
Modulation: The radio frequency oscillator generates a carrier wave, which is then modulated in frequency by the amplified audio signal. This modulated signal contains the audio information.
Power Amplification: The power amplifier amplifies the modulated signal to a level where it can drive the antenna.
Transmission: The antenna broadcasts the modulated signal as radio waves. These waves can be received by FM radios tuned to the same frequency.
To sum it all, an FM transmitter uses an electret microphone to capture audio, amplifiers to boost the signal, an oscillator to generate a carrier wave, modulation to embed the audio onto the carrier wave, a power amplifier to increase the signal strength, and an antenna to broadcast the signal as radio waves. This allows the transmitted audio to be received and played back by FM radio receivers within range.
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