View single post by Slider2732
 Posted: Nov 28th, 2013 12:27 AM
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Joined: Mar 3rd, 2008
Location: Muskogee, Oklahoma USA
Posts: 349
Hey, welcome oldfowler :)

How strange to see your post, unless you are the same chap who contacted me today on YouTube about this ?
I also found the coils today while moving some parts and was reminded of the experiments..that was before getting the YouTube message.

Yes, i'll certainly's a fascinating device and of great interest if you follow the work of classic scientists. Simply to make something that appears to be from the time period of Edisons life.
I'd recommend a study of crystal radios, reading and building, to familiarise with the basic operation of such a circuit. Once you get a crystal radio going, the building of this device becomes more familiar and logical.
The principle seems to be two coils with a slight difference between them of received signal (spirit voice), then a diode to give the sound output.
Experimenting is key and to not follow everything to the letter.  A 'feel' for what is going on is needed, such as noting differences when coils are spaced to different distances. I'm sure there are improvements that can be made to the circuit. For one thing, an audio amplifier on the output, for use as a hand held unit and real time EVP reception.

For ferrite cores, do you have an old PC power supply or old computer that you could take apart ? If not, try advertising on your local Freecycle group for one.
Inside the power supply you'll find 2 or 3  thin ferrite pieces that are wrapped with about half a dozen turns of thick gauge wire. The ferrite pieces look somewhat like thick pencil graphite.  The wire on those is normally glued in place, but the glue bond can be broken by twisting the wire.
If you have an old tube PC monitor then you have a treasure trove of spares for projects like this. Including a relay. Relay wire is hair thin and breaks easily, but is ideal for this project. The gauge is approx 40 AWG. Any thicker and the needed 1500 or so turns will produce a coil whose outer turns will have no ferrite influence. Imagine the ferrite sets up a bubble around itself and the wire turns go within that can see that having wire that extends past such a bubble wouldn't help and in fact can degrade the coil performance.
The wire is called magnet wire, but isn't magnetic. Simply copper wire with a coating on it to stop it shorting out on itself with the next turn of wire over the top.

Build one in 20 minutes !
One quick method of emulating this circuit is to use 2x 12V relay and a germanium diode.
The relays can stay intact, just use a multimeter to find the 2 pins with high resistance as that will be the coil inside. Then connect the diode and output via an audio jack to a powered PC speaker.
Space the relays such that you receive favourable results :)

Last edited on Nov 28th, 2013 12:32 AM by Slider2732