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DIY Hobby projects, diagram, schematic

Electronic Circuits

DIY Hobby projects, diagram, schematic

Condenser Mike Pre-Amplifier Circuit

electronicecircuits, April 13, 2010August 17, 2023
Condenser Mike COND MIC Pre-Amplifier

Condenser Mike Pre-Amplifier Circuit

COND MIC,
need often arises for a sensitive sound pick-up device, whether it is to be used as a simple microphone or a more exotic device as a sound operated alarm, a bugging device or a sound operated flash (for stop action photography) the list is quite unending. Below mic preamp circuit use two npn transistors.

The circuit given employs a condenser microphone as the transducer. Since output of the condenser microphone  is quite low, it usually has an FET amplifier built into the case.

Condenser Mike Pre-Amplifier Circuit mic microphone diagram

PARTS LIST
R11.2k
R22.7k
R333k
R46.8k
R53.3k
R6100
R7560k
R84.7k
R91k
VR110k
C147µF 10V
C20.1µF
C30.1µF
C4220µF 10V
C510µF 10V
Q1BC149C
Q2BC147B
MICCondenser Mike

This amp is powered by the R1, R2 resistor network.

The output of condenser microphone is fed to a two stage amplifier. Transistor T1 (BC149C) utilising current series feedback forms the first stage. The second stage comprising transistor T2 (BC147B) is connected in the voltage shunt feedback configuration. These two stage provide sufficient gain to pick up even the slightest whisper.

The circuit requires a 4.2 volt supply.This may be obtained, as in the prototype, with a 1kΩ (R9) resistor as shown in the diagram. The value of this  resistor may be altered. to suit a supply voltage other than 6 volts.

Condenser Mike COND MIC microphone pin configuration
Condenser Mike Pin Configuration

Output of the microphone amplifier can be made variable by connecting a 10kΩ potentiometer / Preset as shown.

This mic preamp circuit gain can be increased by reducing the value of R6 to 47Ω or 22Ω, depending on the input sensitivity of the main amplifier system. Increase in gain was also observed by using 3V supply and eliminating R9 altogether. The microphone should be housed in a small round enclosure.

Please send your ideas, which are very important for our success…

Electronic Circuits PreAmplifier Circuits

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Comments (15)

  1. Taylor Dyke says:
    April 20, 2010 at 1:32 am

    This circuit works great!, how can i reduce some of the background noise leaking through the circuit?

    Reply
  2. seetharaman says:
    April 29, 2010 at 3:24 pm

    Hi Taylor shift the volume control between mic and Q1. It will solve your problem

    Reply
  3. Wilson Gates says:
    May 28, 2010 at 4:57 am

    Really awesome article! Honest..

    Reply
  4. Steve says:
    May 28, 2010 at 1:41 pm

    This circuit works great!, how can i reduce some of the background noise leaking through the circuit?

    Reply
  5. Dirk Davis says:
    May 30, 2010 at 3:32 am

    Incredibly great read. Truely.

    Reply
  6. Emily says:
    June 1, 2010 at 6:28 am

    Hi Taylor shift the volume control between mic and Q1. It will solve your problem

    Reply
  7. Beverlee Mandino says:
    October 1, 2010 at 4:30 am

    amazing things thanx

    Reply
  8. best roulette system says:
    October 10, 2010 at 11:43 pm

    Bookmarking now thanks, found you through Bing.

    Reply
  9. make music online says:
    October 25, 2010 at 3:50 am

    You seem very knowledgeable in your field.

    Reply
  10. Rajeesh BK says:
    January 5, 2011 at 8:34 am

    It is very usefull
    thanks

    Reply
  11. Garren Handson says:
    March 13, 2011 at 2:51 pm

    Hi this really helped me a lot, however would it be possible to incorporate a on/off power switch for the battery or voltage source?

    Also how would I hook this preamp circuit to an amplifier circuit?

    Reply
  12. Garren Handson says:
    March 13, 2011 at 2:55 pm

    Also would it be possible for you to send me some pics of the finished circuit?

    Reply
  13. kiran says:
    March 22, 2012 at 7:21 pm

    hi sir,
    can i know what is this circuit exactly?i think that when i speak from mic the sound will be heard by the output[speaker]am i right please tell me because i am a beginner.
    thank-u

    Reply
  14. Rumira Daksith (age13 ) says:
    July 16, 2013 at 11:59 am

    this circuit is grate

    Reply
  15. Posporo says:
    March 29, 2014 at 4:45 pm

    Hello newbie here… I would like to ask if theres any substitute for the transistors because they are not available here. Thanks 🙂

    Reply

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