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FM wireless microphone circuit diagram

This is a FM Wireless Microphone circuit. Which we add one transistor in the RF amplifier. So this circuit has two resonance circuits and also two trimmers. This cause has the Higher efficiency and transmission far up.

Technical information.

  • Use DC Power supply of 9V
  • Maximum consumption current about 10mA
  • Transmission frequencies in the 88 MHz.
  • PCB dimensions: 1.64 x 1.54 inches.
  • The working of FM wireless microphone

    Two transistors fm wireless microphone circuit
    Figure 1 Two transistors FM wireless microphone circuit

    The microphone acts as the audio receiver to convert voice to an audio signal. It will come to C2-coupling capacitor into the base of TR1-transistor.

    Which this transistor and a few parts around itself, have 2 functions.
    First, they generate the high-frequency oscillator.
    Second, they mix the audio signal into radio frequency (RF).

    Then, the RF comes to the base of TR2 through the coupling capacitor-C5. The TR2 amplifies the RF comes out of collector, send out of the antenna.

    At collector of TR1 and TR2 will have a copper wire, easy to builds. They are working like a general coil.

    How to builds its.
    components layout and wiring

    As Figure 2, the components layout and wiring of this project. I am so sorry for cannot show PCB layout for you.

    FM wireless microphone circuit that assembly is completed
    Then Figure 3, the complete FM wireless microphone circuit on PCB.

    Testing the FM wireless microphone

    First, apply the 9 volts battery to the positive terminal (+9V) and negative (G terminal).
    Second, for ANT point connects to the coil.

    You need to scrap the liquid coatings out of the copper coil before soldering it.
    Then, Set the FM radio stations to positions 88 MHz.
    Next, use a plastic screwdriver to gently adjust the trimmer VC1, Until it whistles howling out the radio.

    After that, Try to speak into the microphone.

    However, if no sound on speakers. You may try to turn the radio to about 100MHz. If this is still no sound, you turn the radio all the way to 108MHz and try again.

    Then, adjust Trimmer-VC2 in order to get more distance.

    Also FM wireless transmitter

  • FM wireless transmitter circuit
  • Electric guitar FM transmitter circuit from Acoustic
  • FM transmitter circuit, 2 watts (2 kM)
  • The components list.
    R1, R2—27K
    R4—270 ohms
    R6—470 ohm
    C1—0.022uF (223)
    C3, C6—0.01uF(103)
    C4, C5—3pF
    TR1, TR2—2SC458, 2SC828, 2SC945, 2SC1815
    Buy this kit here!

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    This Post Has 9 Comments

    1. how can i get the pcb for this project?
      because the coils is printed on board

    2. Hi,ami rosenberg
      Thanks for your feedback.
      I am sorry for not have PCB layout.

    3. what distance it work?
      please tell me

    4. Hi may I know the value of the trimmer and the L1

    5. Hi,All
      I am sorry this is circuit Kit only.
      so I can not show you trimmer and L1

    6. hi there!nice project.i wonder if this could be used for guitar to have a simple wieless guitar system?will i be modifying the circuit if this would be used as such?thanks in advance

    7. hi I cannot know the value of the trimmer.

    8. Is your country not an English speaking one? because you make many grammatical mistakes in your post, and you didn’t even try to correct them… well, I didn’t get you explanation wella

      1. Hi Professor,
        I’m sorry to trouble you.You said very correctly. My english is not very good. I tried to practice when I have free time.

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