Addictronics

A coherer is the earliest form of radio and is was one of the steps in achieving that. It consists of small metal shavings between two contact posts inside a small tube. When a radio or Electromagnetic Force (EMF) is received by a coherer, its resistance changes dramatically, as shown in the following videos and pictures. I have constructed my own coherer with a small piece of rubber tubing and two bolts from the local hardware store. By hooking up a barbecue igniter to some copper wire (allowing a spark to jump in between) I was able to create my own strong (but short range) EMF fields.

Here is the Coherer connected to my multimeter showing resistance.

A Close up shot of the Coherer shows the metal shavings (acquired by grinding on a piece of steel) are held between the two bolts inside the tubing. The piece of copper wire sticking out the side was just me playing around with different situations, materials, and whatever else I could think of. I do think that I have the metal shavings packed to tightly inside the tubing. I will try a less dense version later.

This barbecue igniter was purchased at the local hardware store with the rest of the parts. In my never ending curiosity I attached two pieces of heavily taped coat hanger wire to it. By bending them just far enough apart I could achieve a decent spark. By sparking practically everything in my house I was surprised at most. Certain silver and gold crackle picture frames would practically light up when sparked, I’m guessing the metal in the paint was conductive enough to allow this light show, check it out yourself sometime. Back to the project I then attached some copper wire to the bare ends of the coat hanger wire to get better range with it. That way I could be up to about 20′ away from the cohere and still see the results.

By attaching some more copper wire to either side of the coherer I noticed an improvement in the performance.

Here is a picture of the multimeter after spark. I have heard that if you use a small enough voltage through your coherer and measure the resistance that way, then you won’t have to reset it after each spark. Resetting it is basically thumping, or even gently tapping, the cohere to shift the metal shavings back to their previous state. When set off the metal shavings will micro weld themselves together, changing the resistance through the coherer.

Here is one video of the coherer in action. I noticed that the barbecue igniter makes the camera auto focus go haywire.

Videos

Notice when I tap the coherer that it resets back to no resistance.

I have no idea why the focus is freaking out.