Capturing Audio from the ground at the same time as capturing audio from the air
This page describes my hack to the Lawmate receiver to capture ground based audio.  The goal was to allow me to maintain a running commentary on the ground as I tweaked my video setup, essentially maintaining an audio diary of the process which would allow me to refine the setup as I went along.
Credit where Credit is Due
The person who first implemented this hack, and inspired me to do the same, was a good friend of mine who goes by "Quacker" on the Ezone.  Nothing I have done here was my own idea.  Oh, and the receiver is available from
There wasn't a great deal to this hack, so I'll describe it in two picture (Click the picture at right for a larger version).  I used an audio preamp board from MPJA.COM.  The microphone was removed and a jack was soldered on, so that a lapel mike could be plugged in.  The output of the preamp board is fed to an RCA jack, which can then be plugged into the left or right audio channel of the camcorder (the other channel would capture audio from the air). The preamp gets it's voltage off the 8 volt regulator in the receiver.  The position for the two jacks were carefully chosen so that they would rest between the other components in the receiver when the lid was closed  (see red outlines in the photo) .  The preamp board was insulated with some tape, and rests on the PIC chip (covered with a QA sticker in the picture) when the cover is closed.   That's it! Click for Larger Picture
Here is a detail shot of how power is tapped off of the output of the receiver's voltage regulator to power the audio preamp board.