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Show FM Transmitter - 4 watts

2016-04-03 22:33  
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The following show is a 4 w FM  transmitter  circuit. The circuit is very simple, and very practical. Recommend Duokanjibian The schematic in order to master this principle. I hope to be helpful to your work. Can be seen in Figure 1, a graphical representation of the frequency modulation. This circuit is that we have already mentioned consists of four stages. Three RF stages and an audio preamplifier modulation. The first stage is an oscillator and RF is built on TR1. The oscillator frequency is controlled LC network l1 example. There C7 and C8 to ensure sustained oscillation adjustment circuit coupling between the oscillator and the second RF stage is an amplifier. It is built on the TR2 operating in Class C tuned through L2 and C9. Finally RF stage is also an amplifier built on the tomb of class C operation input is adjusted by means of C10 and L4. Output from the last stage l3 c12 taken is adjusted by the output signal of the tuning circuit through the air went l5 c11.
In order to properly welded assemblies you should do the following:
- Clean the component due to a small piece of sandpaper. Bend them in the correct distance from the component's body and insert the component in its place on the board.
- You may find sometimes a component of the usual heavy gauge leadership, too thick to enter in the orifice of petty cash. In this case, use a tiny drill holes to expand slightly.
- Do not let the hole is too big, because it is difficult to make after welding.
- With hot iron and place components on the tips of the wire lead while holding the end of the local leadership to get rid of the board. Iron tip must touch the lead slightly above the PC board. - When the solder starts to melt, until it covers the hole near the uniform flow and flux sores and get off at the foot of the solder. The whole process should not exceed 5 seconds. Remove iron and allow the solder to cool without blowing it or moving components. If everything is correct surface must have a bright metallic paint their joint edges should be smoothly ended on the component lead and the board track. If the solder looks dull, cracked, or has the shape of a blob then you make a dry joint and you should remove the solder (pump, or a solder wire) and redo it.
- Be careful not to overheat the tracks, it is easy to upgrade them from the board and break them.
- When you are soldering a sensitive component is a good habit to maintain its leading position from the component side of the board and a pair of long nose pliers any heat that may damage components 

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Parts List

R1 = 220K
R2 = 4,7K
R3 = R4 = 10K
R5 = 82 Ohm
R = 150Ohm 1/2W x2 *
VR1 = 22K trimmer

C1 = C2 = 4,7uF 25V electrolytic
C3 = C13 = 4,7nF ceramic
C4 = C14 = 1nF ceramic
C5 = C6 = 470pF ceramic
C7 = 11pF ceramic
C8 = 3-10pF trimmer
C9 = C12 = 7-35pF trimmer
C10 = C11 = 10-60pF trimmer
C15 = 4-20pF trimmer
C16 = 22nF ceramic *

L1 = 4 turns of silver coated wire at 5,5mm diameter
L2 = 6 turns of silver coated wire at 5,5mm diameter
L3 = 3 turns of silver coated wire at 5,5mm diameter
L4 = printed on PCB

L5 = 5 turns of silver coated wire at 7,5mm diameter

RFC1=RFC2=RFC3= VK200 RFC tsok

TR1 = TR2 = 2N2219 NPN
TR3 = 2N3553 NPN
TR4 = BC547/BC548 NPN
D1 = 1N4148 diode *
MIC = crystalic microphone





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