Speaker Microphone circuit diagrams


Posted on Feb 6, 2014

This circuits allows you to use a cheap loudspeaker as a microphone. Sound waves reaching the speaker cone cause fluctuations in the voice coil. The voice coil moving in the speakers magnetic field will produce a small electrical signal. The circuit is designed to be used with an operating voltage between 6 and 12 volts dc. The first transistor op


Speaker Microphone circuit diagrams
Click here to download the full size of the above Circuit.

erates in common base mode. This has the advantage of matching the low input impedance of the speaker to the common base stage, and secondly has a high voltage gain. The second stage is direct coupled and operates in emitter follower. Voltage gain is slightly less than unity, but output impedance is low, and will drive long cables. Speech quality is not as good compared to an ordinary or ECM microphone, but quite acceptable results can be obtained. Speaker cones with diameters of 1 inch to 3 inches may be used. Speaker impedance may be 4 ohm to 64 ohm. The 8. 2 ohm resistor value may be changed to match the actual speakers own impedance.




Leave Comment

characters left:

Related Circuits

  • New Circuits

    .

     


    Popular Circuits

    Fish Tank Lights and Temperature Detector
    NiCad charger with independent discharge
    Siren
    Switching Improves Regulator Efficiency
    Tron Disc with .NET Microframework
    infrared Help Troubleshooting This Circuit
    control circuit for nokia tv tuner 5827
    temperature sensor circuit using lm335
    bluetooth based smart home
    Doorbell Phone
    gps altimeter
    PLL Synthesizer for 150 MHz Local Oscillator
    SA2132 AM/FM RADIO RECEIVER
    Voltage Controlled Voltage Source
    Low Frequency Antennas
    PERIOD TO VOLTAGE CONVERTER
    Automatic lighting control telephone signals



    Top