Apologies my original question was completely unhelpful, I'm trying to make a USB condenser microphone, and the tutorial I was trying to follow used two electret condenser microphones, which were wired like so: Wiring Diagram

I unfortunately was sold two "real" condenser microphone elements, which have three poles (V+, Ground and Output) and did not realise my mistake until I was home, making it impractical to return them.

I would like to know how to connect these three pole elements to the circuit instead of the two pole ones that are used.

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    \$\begingroup\$ I'm sorry but the stuff on the link you provided just never got to the heart of what you are trying to do and I got bored and annoyed (slightly) after 30 seconds and thought "why doesn't the person asking this question describe what he or she is trying to do instead of letting everyone waste their time on a stupid website". Maybe you were too busy taking the stuff back to radio shack? \$\endgroup\$ – Andy aka Jun 19 '14 at 16:54
  • \$\begingroup\$ I agree. The idea needs to be explained here - at least to the extent to which you begin to have problems. As for the microphone difference, what does it matter to you? Without more information it would seem the only thing you need to consider is the output, preamp requirements, and frequency response for either microphone type. I don't see any reason why it would matter which type of microphone is used. \$\endgroup\$ – sherrellbc Jun 19 '14 at 17:02
  • \$\begingroup\$ I have rephrased the question, explaining exactly what is needed. \$\endgroup\$ – ja_ke Jun 19 '14 at 17:13
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    \$\begingroup\$ @sherrellbc: It matters because a "real" condenser microphone capsule requires an external bias on the order of 60-100V in order to produce a signal, while an electret capsule effectively has that bias built-in. You also need a very high-impedance preamp to go with the "real" capsule, while most electret capsules have a FET preamp built in as well. Dave Jones and Doug Ford have recently produced a nice series of videos on this topic. \$\endgroup\$ – Dave Tweed Jun 19 '14 at 17:20
  • \$\begingroup\$ Based on the rephrased question, it would seem that you just have a different type of electret capsule, not a true condensor capsule. \$\endgroup\$ – Dave Tweed Jun 19 '14 at 17:23

It sounds like the microphone capsules you bought have the preamp load resistor built in, in which case, you can hook them up like this:


simulate this circuit – Schematic created using CircuitLab

  • \$\begingroup\$ Thanks, I think, I'm struggling to understand your circuit diagram, but I think I'll get there. I should add that I'm a novice when it comes to electronics and can sometimes get confused easily. I have a question though, about the potentiometer (R3) on the diagram, how would I mount this so that anti-clockwise=down, clockwise=up? Another question (last one I promise), would it be ok to use two 18k resistors in parallel, giving 9k total, in place of the two 10k resistors? \$\endgroup\$ – ja_ke Jun 19 '14 at 17:53
  • \$\begingroup\$ @Phox, you can make 10k resistance anyway you'd like. It's just that changing the resistance values will affect your biasing voltage a bit, but then again its coupled to the MCU anyway so it shouldn't matter. \$\endgroup\$ – sherrellbc Jun 20 '14 at 5:58
  • \$\begingroup\$ @Dave, what is R3 for? Is that some sort of feedback? I am not very familiar with MOSFET configurations. \$\endgroup\$ – sherrellbc Jun 20 '14 at 5:59
  • \$\begingroup\$ @sherrellbc R3 Is actually a variable resistor, it's there for sensitivity. Also, I was asking Dave if 9k would work, as I'm not great at this... \$\endgroup\$ – ja_ke Jun 20 '14 at 12:23
  • \$\begingroup\$ @Phox, From a qualitative standpoint sure, but things often get more difficult to explain if you come from the quantative side (which is more important to me at least). I thought I had addressed that 9k should work but your biasing voltage would be a bit different. C3 decouples the microphone signal from the amplifier circuit, so we have only an AC waveform going into the base of the NPN transistor Q1. However, with R3 present it seems as if there is a supplement base current coming in that introduces some positive feedback into the system. I do not quite understand that configuration. \$\endgroup\$ – sherrellbc Jun 20 '14 at 12:40

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