I was under the assumption that electret microphone capsules do not require any phantom power an can be connected in the same way dynamic microphone capsules can be, due to the fact that they contain a small permanent static charge built in. I am trying to build a really simple mic to hook up to my computer via the 3.5mm mic jack, and after wiring everything up, it doesn't seem to be working. Is this because there is in fact supposed to be some sort of phantom power circuit, or should I just double and triple check my wiring again?
Electronic – Do electret condenser microphones require phantom power
microphone
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In terms of actual directionality, you'll probably just have to test them by measuring the response to a source at different angles. Normally this would be done in an anechoic chamber, but you might be able to accomplish something by supporting the microphone on a post well off the ground in the center of a large carpeted room and walking around it with the source, or outside on a calm day. You could tie a string to the post to measure a consistent radial test distance.
Directionality will probably be somewhat different at extremes of frequency.
Since your source probably wouldn't be omni-directional, try to be consistent for example always aiming it at the microphone.
Yes, they have polarity and it has to be right to work- the output needs to be biased positive with respect to the ground terminal.
The ground/GND terminal should be common with the case, so you can check polarity with a multimeter.
Here, from a Panasonic Datasheet, is a typical arrangement:
The two diagrams you show are equivalent, one is just drawn upside-down (potentially.. as it were.. confusing and not to be encouraged, but still valid).
Best Answer
Electrets don't need phantom power for the diaphragm, but the small capsules usually have a FET buffer inside which needs bias voltage. This can of course be derived from a phantom power source if necessary.
Here is a typical electret circuit:
The value of the resistor is usually between 2k and 10k (cap say 10uF or higher) The datasheet for your capsule will probably give recommended operating conditions.
Here's a good link on simple electret circuits.
Another page with some more advanced ideas.