This picture was dated Oct 2002 so I had already built it and put it into service by then. I took the handset of an old phone, and sawed off the handle and microphone, leaving just the part that holds the earphone. I built the circuit on a piece of perfboard and installed it in the back cover of the earphone enclosure, and mounted the AA cell holder to the outside – you can see where the black battery wire goes through a hole and then back behind. The electret microphone seen close and to the right plugged into the black jack next to it. For the switch I just folded up a small square of paper and put it between the positive end of the battery and the holder.
