How to Make a Secret Listening Device

By Palmer Owyoung

A secret listening device can be used to eavesdrop in on conversations that you wouldn't otherwise be privy to. You can make an inexpensive one using a digital recorder and a stethoscope. This will allow you to listen to people talking through walls. However you should only use such a device in accordance with the law. So make sure that you do not use it at a property that you do not legally rent or own.

Things You'll Need

  • Stethoscope
  • Y-connector
  • Digital recorder
  • Drill

Step 1

Buy a stethoscope and two multimedia microphones. The stethoscope is available at local drug stores for just $10.00 as of 2010. You can use an old stethoscope if you have one. The multimedia microphone can be bought at a local electronics shop for around $15.00 as of 2010.

Step 2

Disassemble the microphone carefully. You will notice two mini-condenser microphones that are installed inside the casings. Do not disconnect the mini-stereo plugs from the condenser microphones. Just remove the casings that enclose the microphone.

Step 3

Remove the earpieces on the stethoscope and enlarge the holes using a drill so that they match the earpieces on the mini-condenser microphones

Step 4

Put the mini-condenser microphones into the holes of the earpieces.  Reassemble the earpieces on the stethoscope. If necessary use glue to stick the earpieces back into their position.

Step 5

Connect the mini-stereo plugs into the digital mini-connector using the Y-connector. Place the chest piece of the stethoscope to a wall or door where you wish to listen to a conversation and press the record button on the recorder. You can also hide the stethoscope inside of a room with just the part that goes against the chest sticking out.