Monday, January 13, 2014

FM transmitter 800m (2400ft)

FM transmitter 800m (2400ft) 




This fm wireless transmitter should only be used for educational purposes.
Regular transmission using such a transmitter without a licence is illegal in most countries.
I would like to tell you not to use this for illegal things

This is one of the smallest and neatest FM transmitters to be presented as a construction project
This will save going to a number of suppliers as no single supplier has all the 
necessary components. 

FM transmission is the best mode for transmitting a signal as it does not suffer 
from interference such as electrical noise from car engines or electrical appliances
etc. It also achieves the greatest range with the least power.
With just a handful of components and a few milliwatts of output power you can 
produce an FM transmitter with a very impressive range and perfect clarity.

With a 175cm (5ft 9in) (half-wave antenna) the range has been 
conservatively rated as 800 meters (2400ft) under normal working conditions. In many 
countries you must reduce the maximum range to 30ft (10 meters) by cutting the antenna
to 10 inches. If this is the case, you must abide by it. Some countries totally ban
these brilliant devices. You need to find out the situation in your own locality.
Using a battery for powering the circuit will reduce noise. 






For More Details Visit 

PARTS LIST


SEMICONDUCTORS

2 - 2N2222   (NPN transistors)      Click Here to view Datasheet

RESISTORS

1 - 470R  
1 - 10k    
1 - 47k   
1 - 68k   
1 - 1M    

CAPACITORS

1 - 10p ceramic-disc 
1 - 39p ceramic-disc 
1 - 1n ceramic-disc 
2 - 22n ceramic-disc
1 - 100n 

1 - 5p to 30p air trimmer

ADDITIONAL PARTS AND MATERIALS

1 - 5 turn coil 0.020inch (0.5mm) enamelled wire 1/8in (3mm) diameter
1 - electric microphone
1 - 9v battery 
1 - 9v battery snap
12in (30cm) fine solder
5ft 9in (175cm) hook-up wire.




SUMMARY OF SPECIFICATIONS

Supply:- 9 volts
Current consumption:- 7mA
Tuning range:- 80 - 110MHz (by stretching or compression the oscillator coil)
Fine tune by adjusting the air trimmer (2MHz adjustment)
Stability:- Low. Bug to be left in-place and not to be moved or handled.
Antenna length - 175cm (5ft 9in)



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