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This is a simple FM transmitter, with great range, being able to reach more than 2.5 km of distance, using a suitable antenna, powered by a power supply or a 12Vdc battery.
The circuit has a frequency range that can be tuned between 88 and 108 MHz, and is quite stable, and can be used for small audio transmission links, or as community radio, and with great audio quality.
The Transmitter
ATTENTION!
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Characteristics!
- High sensitivity of audio pickup
- 12V to 16Vdc supply voltage
- Simple circuit to assemble
- Great range, about 2.5km
- Easy assembly
Circuit Operation
The circuit uses two RF transistors; Q1 2N2218 used as RF oscillator, and transistor Q2 2N3866, used for power stage.
The decouple electrolytic capacitor C1, receives the audio signal, who comes from a signal source, which can be a soundboard, a USB audio card, a musical instrument, or any other signal source.
This modulated signal is sent to the base of transistor Q1, it works as an oscillator circuit, the trimmer VC1 in parallel with the coil L1, adjusts the circuit operating frequency.
Transistor Q2 works as the power stage of the transmitter, it amplifies the RF signal generated by Q1, and sends it to the output, composed by the antenna.
Applications!
- Audio transmitter
- Audio link for instruments
- Wireless microphones
- Spy Microphone
- Homemade FM radio
Schematic diagram
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Fig. 2 - Schematic 2.5KM FM transmitter, using transistor 2N3866 |
Circuit Adjustments
The Power Supply
List of materials
- Semiconductors
- Q1 ............. 2N2218 or 2N2219 NPN transistor
- Q2 .............. 2N3866 or 2N4427 NPN Transistor
- Resistors
- R1, R2 ....... 10KΩ 1/4W Resistor (brown, black, orange, gold)
- R3 ............. 47Ω 1/4W Resistor (yellow, violet, black, gold)
- PT1 ........... 10KΩ Potentiometer
- Capacitors
- C1 ............. 2.2uF /16V Electrolytic Capacitor
- C2, C3 ....... 1nF Ceramic/Polyester Capacitor
- C4, C5 ....... 8.2pF Ceramic Capacitor
- VC1, 2, 3 ... 0 ~ 47pF Trimmers
- Coils
- L1 ............... 4 Turns, 7mm diameter Inductor
- L2 ............... 3 Turns, 7mm diameter Inductor
- L3 ............... 5 Turns, 7mm diameter Inductor
- L4 ............... RFC - 10uH Inductor *See Text
- Miscellaneous
- P1, P2 .... Screw Terminal Type 5mm 2-Pin Connector
- Other ........................... PCB, Wires, Speaker, etc.
In Figure 3, we provide the PCB - Printed Circuit Board, in GERBER, PDF and PNG files. These files are available for free download, on the MEGA server, in a direct link, without any bypass.
All to make it easier for you to do a more optimized assembly, either at home, or with a company that prints the board. You can download the files in the Download option below.
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Fig. 3 - PCB - 2.5KM FM transmitter, using transistor 2N3866 |
Files to download, Direct Link:
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My Best Regards!
thanks
ReplyDeleteHello EVILACHARYA
DeleteThank you!
Regards!
Hola que tal!! Estoy montado el circuito, pero hay un error en los valores de las resistencias , R1 y R2 , es decir el valor de 10K esta bien, solo la descripción, que dice Marrón, Negro, Rojo , para los que comienzan y no saben la ley de ohms se pueden confundir, si se guían, por lo que dice, en este caso 10K es Marrón, Negro, Naranja. Gracias por el aporte. Saludos
ReplyDeletehola @SANDOR TV & PC
DeleteSí, tienes razón, era rojo en lugar de naranja, para la resistencia de 10K.
¡Gracias por su contribución, la guía de colores ahora ha sido corregida!
¡Gracias!
Hola. Quisiera hacer una consulta sobre el transmisor de Fm. Lo monte, y no me funciona bien Gracias
ReplyDeleteHola @SANDOR TV & PC
DeleteHáganos saber lo que no funciona... Para que podamos ayudar.
Hicimos uno de estos y funciona perfectamente. Una cosa, ¿el transistor que estás usando es original? Tenga cuidado con los transistores falsos que se venden en Internet.
¡Mis longitudes!