by piesi, published
A printable A-B-Stereo Microphone
I wanted to have a mic which I cought use for general purpose recording in conjunction with my old iriver h120 (with rockbox installed). I didn't found a suitable mic without a build in recorder:)
So after a little bit googleing I found this article about a low-cost
homebrew solution http://www.wildlife-sound.org/equipment/technote/micdesigns/ and decided to get a bunch of these panasonic wm61-capsules described in the article to start experimenting with them - here is the result.
A special feature of this microphone is it's variable stereo width (by time-of-arrival stereophony).
The button near the audio jack is the on/off-swiitch, the second one a gain boost. By swapping two resistors in the circuit, the gain boost could be easily converted to a gain damp. The preamp circuit isn't necessary at all, if your recorders preamp has phantom power. But the 9v battery increases the headroom for louder signals and powers the 4 capsules more convenient. The distance between capsules and preamp shouldn't boo to long.
I'm quite happy with the sound. You can download some audio examples here: https://github.com/Piesi/pMic/tree/master/docs/audio_examples
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Non printed parts:
-2-4 Panasonic wm-61 electret condenser capsules (4 give better signal to noise ratio)
-2 M4 bolts ~12mm
-8 M3 bolts ~15mm
-1 M3 bolt 30mm
-4 M4 nuts
-50cm enameled copper wire (0.2mm)
-a simple preamp circuit (the included schematic is a fritzing-file http://fritzing.org/download/)
-two rubber bands
easy to print, except the case parts need support.
it`s a simple preamp circuit based on a tl072 op-amp. The board is 69*18mm. You can take all information from thr .fzz-file.
The rest might be figured from the pictures and the files (I'm too lazy to descibe in further detail, but helpful if you're stuck and need advice:)