Showing posts with label fm. Show all posts
Showing posts with label fm. Show all posts
Tuesday, May 14, 2013
Spy FM Transmitter circuit
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This is so impotent circuit for us,Because we can use this circuit as a spy unit.This circuit can transmit signals about 30m.And the other important thing is the power of this circuit we can operate this circuit with 1.5v to 3v(1.8 mA at 1.5 Volts )
Note
# If you are unable to find the transistor here use these transistors Because here you can use equal transistors such as 2N2222A, BFxxx series, BC109B, C, and even well known BC238.
# Use 1.5v to 3v for this circuit.Dont supply more than 3v(3v can cover the max range 30m)
Monday, April 8, 2013
5 Watts FM RF Amplifier
This
fm rf amplifier uses 2SC1971 transistor to provide 5 watts of output.
Output matching is adjusted via the two 40pF trimmer capacitors
likewise also to the input. Note that the emitter of this transistor is
directly grounded on the heat sink and should have a good thermal
transfer. Driving power of 100 to 200mW can be applied in order to
provide 5watts of output. Use a dummy load to tune this amplifier and
remember that the transistor is biased in Class C, sufficient
filtering should be followed after the output to minimize all the
harmonics. Use ground plane construction technique in the PCB lay-out
for best result, the more the grounding the better. If you have hard
time finding the 10uH rf choke, try to wind 1/2 meter of 0.2mm enamel
wire over a 33K 1/2 watt resistor and solder the coil ends to the legs
of the resistor.
fm rf amplifier uses 2SC1971 transistor to provide 5 watts of output.
Output matching is adjusted via the two 40pF trimmer capacitors
likewise also to the input. Note that the emitter of this transistor is
directly grounded on the heat sink and should have a good thermal
transfer. Driving power of 100 to 200mW can be applied in order to
provide 5watts of output. Use a dummy load to tune this amplifier and
remember that the transistor is biased in Class C, sufficient
filtering should be followed after the output to minimize all the
harmonics. Use ground plane construction technique in the PCB lay-out
for best result, the more the grounding the better. If you have hard
time finding the 10uH rf choke, try to wind 1/2 meter of 0.2mm enamel
wire over a 33K 1/2 watt resistor and solder the coil ends to the legs
of the resistor.
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