View single post by joecioppi
 Posted: Mar 28th, 2009 08:13 PM
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Joined: Sep 22nd, 2008
Location: Doylestown, Pennsylvania USA
Posts: 130
RHGHAngel wrote: Hey Hey!!:biggrin: How are you today? Well, I hope. I have a Question or 2 or 3 for you maybe you can help me out. LOL I am Confused on how to Build the Germanium Diode recorder. Let me just start by telling you what I did. I Cut off the Microphone from my Mini Cassette recorder Mic. I attached a Germanium Diode to the white wire... It was the only wire in there other than the wire surrounding it. I am assuming that is the Grounding Wire. In any case, I have no way to Solder, so I twisted the wire onto the Germanium Diode. On the other End of the Diode, I attached Another wire assuming this was supposed to act as an Antenna? The Germanium Diode has a Black dot on one end. That is supposed to be facing in the Direction of the Jack that you plug into the recorder Right? Or do I have this All Wrong? LOL Please Help Me


Hi Angel,

I'm a disabled electrical engineer who has been studying the paranormal for the last few years. The "Raudive" detector is an untuned crystal diode detector that folks have been connecting to recorders lately to pick up EVP voices.

The use of the germanium diode has been popular because it has a low conduction voltage threshold which allows it to detect low level radio noise. The radio noise or atmospheric static is rectified by the diode and coupled to the recorder input. Since the noise currents have to pass through the diode to detect EVP sounds to record, the diode has to be connected to other components that provide a path for the signals to follow.

A radio choke coil, diode, and resistor form a circular path for signal currents picked up by a small antenna. The diode detects sounds included in the noise and the sound signal appears across the resistor. The resistor is connected between the center wire of your mic cable and the shield braid return around the outside. That signal is then recorded by the recorder.

I've attached a mspaint drawing of the connection diagram. I've built this into a mic plug with miniature components for other experimenters like yourself.


Attached Image (viewed 6869 times):

raudive detector.bmp