Have you ever considered buying one of those hi powered microphones often seen in eletronics magazines, but thought it was to much to buy and to small to card? The circuit shown in this file will provide you with the information to build one for a lot less money.
These audio eavesdropping devices are probably one of the hottest items in the underground due to their ability to pick up voices through thick walls. You can also attach the speaker wires to a tape recorder and save all the conversation. As one can see these are great for blackmailing a teacher, classmate, principal, neighbor, or whoever you seek services from…
M1 Amplifier Module. (Lafayette 99C9037 or equiv.)
M2 9-VDC battery.
R1 20K poteniometer with spst switch.
S1 Spst switch on R1
SP1 8-ohm speaker
T1 Audio transformer (Radio Crap part 273-1380)
S1 here is on the potentiometer
M3 can be an earphone earpiece
We hope that this schematic will aid you to craft Electronic Eavesdropper on your own. Enjoy and have fun!