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The principle of an FM transmitter

2016-04-03 08:13  
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Next is an FM transmitter schematic presentation. Schematic showing below. In order to get a little tuning coil can put 4-40pF trimmer  capacitor  (optional) parallel in 1μH coil, L1. C1 / C4 and C5 / C6 is a ceramic capacitor, preferably fasting (low noise) type. C2 / C3 is electrolytic or can be tantalum types. Antenna is only a 12 "cable or a piano wire from 6" 12. "Before reading schematics, there are several points to note: 1, found that the signal receiver, ensure that there is a signal into the microphone, otherwise the circuit will not work. 2 , looking at the click of a microphone signal receiver position. 3, select more temperature stable capacitors to read a few of the schematic diagram will help you to better grasp the principle of this circuit is simple and very helpful.

Small FM Transmitter

R1,R3 = 100K
   R2 = 10K
   R4 = 470 ohm
C1,C4 = 470pF
C2,C3 = 4.7μF, 16V, electrolytic
C5,C6 = 4.7pF
   C7 = 4-40pF trimmer cap (optional, see text)
   L1 = 1μH
Q1,Q2 = 2N2222, NPN transistor
  Mic = Electret Microphone
   B1 = 9 Volt, Alkaline battery


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