Tsukure Studio 10m FM Transmitter

A FM transmitter is a device that uses the principles of frequency modulation to broadcast sound supplied at its input. 

Typical FM transmitter design’s usually follow the block diagram below;

The signal strength of audio inputs into the transmitter is usually low therefore an amplifier is usually built to bring the signal level up. Based on the desired frequency for transmission (which is usually between the FM frequency band, 88MHz to 108MHz), the carrier frequency is generated using an oscillator circuit and mixed with audio signal to create the modulated signal. The modulated signal is then passed through a power amplifier at the transmission stage to create low impedance which is matched with the antenna.

The audio output signal from the microphone is usually small, the first transistor thus performs the job of amplifying that signal to a level good enough for transmission. After amplification as described earlier, the next stage of the FM transmitter is modulation. At this stage the amplified audio signal is then mixed with the carrier frequency at with which the signal is to be transmitted. This carrier frequency can be varied using the 20pF variable capacitor connected with the inductor, and the typical frequency band of this particular design is between the 88MHz to 108MHz and since there is no visual output to recognize the exact frequency at which the transmitter is working, you will need to adjust your FM receiver radio within the range of the frequencies mentioned to get the frequency at which the transmitter is transmitting. After modulating the Audio signal with the carrier frequency, the signal is then sent out through the antenna.

Components used in this module...

Find out more about the components used in this STEM Module.

Let's Get Started!

Below you will find a list of bits to gather before hand, followed by a detailed schematic. Using a breadboard lay out the components and connect them together as shown. Alternatively you can purchase this module from our shop and simply solder the components in the places indicated on the quality assured printed circuit boards provided.

What You Need...

2 101 (100pF / 0.1nF) Capacitor (Ceramic)
1 103 (10nF / 0.01uF) Capacitor (Ceramic)
1 4R7 (4.7pF) Capacitor (Ceramic)
1 20pF Capacitor (Trimming)
1 5mm Red (Diffused) LED
1 Tsukure Studio - 10m FM Transmitter (Pirate Radio) PCB
1 100R
[ Brown, Black, Black, Black ]
Resistor (0.25 Watt)
3 10K
[ Brown, Black, Black, Red ]
Resistor (0.25 Watt)
1 1K
[ Brown, Black, Black, Brown ]
Resistor (0.25 Watt)
1 1M
[ Brown, Black, Black, Yellow ]
Resistor (0.25 Watt)
1 330R
[ Orange, Orange, Black, Black ]
Resistor (0.25 Watt)
2 470R
[ Yellow, Violet, Black, Black ]
Resistor (0.25 Watt)
2 2N2222 Transistor (NPN)

NB: Any resistor colour codes specified relate to 5 band resistor codes, the 5th band has not been shown intentionally. The 5th band indicates the resistor tolerence, we use only the highest tolerence resistors in our products.

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