This is a long-range FM transmitter circuit in the VHF range. As Figure 1: Sonar with up to 2 watts, when used with a supply voltage of about 24V.
In the case of applications typically do not want a high transmission.
This circuit requires only one power supply 9V Only. If used voltage level of the power supply more than 10V.
How it works
We need a heat sink to transistor-Q2, To prevent this transistor overheating.
Figure 1 the schematic diagram of 2W(2 km) 88-108 MHz frequency VHF/FM transmitter
First, try entering the power supply to the transmitter with the 9 volts battery rectangular (006 p).
To reduce the frequency interfere with each other at a distance innocently and another, reduce crashes hum.
If using a normal DC adapter that low quality, may have this problem.
The Horseshoe-shaped Variable Resistor (VR1) is used to adjust the strength of the audio input. The Trimmer -C6 used to adjust the frequency of the transmitter.
The transmitter is a little device Thus creating easy. In particular, it has copper on the PCB that serves as a coil-L in the circuit. It does not need wind the coil L in place assembly.
Figure 2 the PCB layout
Figure 3 the component layout
Do not use a power supply higher than 24V. Because it can cause the circuit malfunction.
And an antenna that works for frequency use.
This circuit can be made waves at a distance of several kilometers.
Asked to take account of the law on this matter.
The parts you will need
C1, C2: 4.7uF 25V, Electrolytic capacitors
C3, C4: 560pF 50V, Ceramic capacitors
C5: 3-9pF 50V, Ceramic capacitors
C6: 10-30pF, Trimmer
R1: 120K 0.25W Resistors
R2, R3, R4: 4.7K 0.25W Resistors
R5: 82 ohms 0.25W Resistors
Q1: BC307A, Transistors
Q2: BC360/BC361, Transistors
VR1: 22K potentiometer (Horseshoe-shaped resistor)
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