4 Watt FM Transmitter

Posted on Feb 7, 2014

This is a small but quite powerful FM transmitter having three RF stages incorporating an audio preamplifier for better modulation. t has an output power of 4 Watts and works off 12-18 VDC which makes it easily portable. It is the ideal project for the beginner who wishes to get started in the fascinating world of FM broadcasting and wants a good

4 Watt FM Transmitter
Click here to download the full size of the above Circuit.

basic circuit to experiment with. As it has already been mentioned the transmitted signal is Frequency Modulated (FM) which means that the carrier`s amplitude stays constant and its frequency varies according to the amplitude variations of the audio signal. When the input signal`s amplitude increases (i. e. during the positive half cycles) the frequency of the carrier increases too, on the other hand when the input signal decreases in amplitude (negative half-cycle or no signal) the carrier frequency decreases accordingly. In figure 1 you can see a graphic representation of Frequency Modulation as it would appear on an oscilloscope screen, together with the modulating AF signal. The output frequency the transmitter is adjustable from 88 to 108 MHz which is the FM band that is used for radio broadcasting. The circuit as we have already mentioned consists of four stages. Three RF stages and one audio preamplifier for the modulation. The first RF stage is an oscillator and is built around TR1. The frequency of the oscillator is controlled by the LC network L1-C15. C7 is there to ensure that the circuit continues oscillating and C8 adjusts the coupling between the oscillator and the next RF stage which is an amplifier. This is built around TR2 which operates in class C and is tuned by means of L2 and C9. The last RF stage is also an amplifier built around TR3 which operates in class C the input of which is tuned by means of C10...

Leave Comment

characters left:

Related Circuits

  • New Circuits



    Popular Circuits

    Audio Line Driver Circuit
    LA3161 based Preamplifier circuit with explanation
    NE 555 & LM 567 Remote Control Circuit
    FM demodulation with RLC circuits applet
    12VDC to 230VAC 60W Inverter Circuit
    Thermometer with PIC Microcontroller
    Build Your Own Gauss Meter
    Bipolar Regenerative receiver
    LM317T Variable Voltage Regulator
    Flickering Light II