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FM Transmitter principle introduced

2016-04-06 09:17  
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This article describes the FM transmitter schematic presentation. Schematics can combine text look better grasp of this principle. Below is a schematic, PC board pattern, and parts placement of the low-energy FM transmitter. The range while running 9 v about 300 feet. It runs from 12 v increase the range of approximately 400 feet. Although a large number of similar second transistor charts available, which is above average. A major improvement in the small transistor of the circuit, as we already discussed, this transmitter comprises two stages. The first transistor for amplifying the audio, which means that now more sensitive microphone sound. The second acts as an oscillator. In this circuit, you need to pay attention to:
1. Mother tongue and foreign language is 5 turns 28 AWG enamel-coated magnet wire wound with the diameter of about 4 mm. Internal pen questions (plastic tube can put ink). After completing the form, and then remove the coil mounted on the circuit board, being careful not to bend.
2. C5 is used for tuning. The transmitter is operating normally broadcast frequencies (88 - 108 mhz).
3. Q1 and Q2 are also  2N3904  or something like that.
4. You can use 1/4 W resistors mounted vertically instead of 1/8 W resistor.
5. You may want to bypass the battery. 01 uf capacitors.
6. An antenna may not be required operation. 

Schematic

This is the schematic of the FM Transmitter

PC board layout and parts placement

This is the printed circuit layout and parts placement of the FM Transmitter

Parts:

PartTotal Qty.DescriptionSubstitutions
C110.001uf Disc Capacitor 
C215.6pf Disc Capacitor 
C3,C4210uf Electrolytic Capacitor 
C513-18pf Adjustable Cap 
R11270 Ohm 1/8W Resistor270 Ohm 1/4W Resistor
R2,R5,R634.7k 1/8W Resistor4.7K 1/4W Resistor
R3110k 1/8W Resistor10K 1/4W Resistor
R41100k 1/8W Resistor100K 1/4W Resistor
Q1, Q222N2222A NPN Transistor2N3904
L1, L225 Turn Air Core Coil 
MIC1Electret Microphone 
MISC19V Battery Snap, PC Board, Wire For Antenna 

 


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