Condenser Microphone - What is it?

Discussion in 'General Electronics Chat' started by vol_, Mar 29, 2016.

  1. vol_

    Thread Starter Member

    Dec 2, 2015
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    Hello everybody!

    Condenser microphone and electret microphone stands for the same thing?
     
  2. Lestraveled

    Well-Known Member

    May 19, 2014
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    Generally, yes
     
  3. vol_

    Thread Starter Member

    Dec 2, 2015
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    And can an electret mic be used in place of a condenser mic and vice versa? The only thing that is different is a wider frequency range of the electret?

    Thanks Lest!
     
  4. kubeek

    AAC Fanatic!

    Sep 20, 2005
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    Not really. Electrets capsules usually have a bulit-in jfet transistor, usually meant to operate at a few miliamps current. Condenser studio mikes have their own amplifier built in, usually meant to operate with 48V bias voltage. Condenser capsules should have none of that and be just a two plates in mid air.

    It would be better if you showed what you want to replace with what and then talk about if the replacement is possible.
     
  5. vol_

    Thread Starter Member

    Dec 2, 2015
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    I want to know if i can use EITHER an electret capsule or a condenser capsule for a hearing aid device that uses a transistor to preamplify or to buffer (?) a signal for a NJM2073 IC mono amplifier (mono in BTW). I want to be able to use both capsules (electret and condenser) for the same circuit.

    The schematic i use is here. I will replace thought the TDA2822M with its contemporary equivalent NJM2073, which shows better proporties.

    Thanks everyone!
     
  6. kubeek

    AAC Fanatic!

    Sep 20, 2005
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    Can you post the datasheet of your condenser capsule? The circuit looks like to be tailored to electret mikes.
     
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  7. Kermit2

    AAC Fanatic!

    Feb 5, 2010
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  8. vol_

    Thread Starter Member

    Dec 2, 2015
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    How can you tell that is tailored for an electret? Sorry, but i still lack the knowledge to conclude it.
     
  9. kubeek

    AAC Fanatic!

    Sep 20, 2005
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    I would guess that a condenser would need a larger supply voltage to have any a reasonable output signal, and the input impedance of the NPN transistor would load it too much.
     
  10. Kermit2

    AAC Fanatic!

    Feb 5, 2010
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    Electret-microphones commonly use jfet input and condenser mics use a 48 volt "phantom" supply.
    Most quality audio mix boards have a setting that will supply the on board circuitry of condenser mics when they are plugged in.
     
  11. Kermit2

    AAC Fanatic!

    Feb 5, 2010
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    Electret-microphones are very small and need a low voltage supply.
    3 volts here.
    hearing-aid-circuit-diagram.gif
     
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  12. vol_

    Thread Starter Member

    Dec 2, 2015
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    So all electret mics need a low voltage to operate, while condenser mics need bigger voltage?
     
  13. vol_

    Thread Starter Member

    Dec 2, 2015
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    what do you mean by saying electrical circuits software? To do what thing? For example simulation, pcb design....?
     
  14. vol_

    Thread Starter Member

    Dec 2, 2015
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  15. GopherT

    AAC Fanatic!

    Nov 23, 2012
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    An electret microphone is a type of condenser microphone. The microphone in the image is an electret microphone. A "standard" condenser microphone needs a DC bias voltage (3 wires) and the bias is normally 12, 24 or 48 volts - depending on the microphone. An electret microphone has the bias voltage built in as a permanently charged capacitor ("electret"). Check the definition of Electret on Wikipedia if you want more - no need for us to retype it here.

    An electret microphone typically has a circuit board with a JFET transistor already built in so it can provide a decent output drive current.

    An electret microphone costing less than one US dollar sounds surprisingly good.

    Note that your circuit may not be extremely efficient with regards to battery life. Electret microphones need a milliamp or so of current so a standard hearing aid battery will not last more than a few 10s of hours with that circuit. check the current draw on your amplifier chip as well.
     
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