Sunday, March 3, 2013

Razor Blade Radio

All right! I admit it! I was one of those nerds as a kid. I loved everything electrical. I read Popular Electronics from cover to cover every time I could get an issue. I strung up all kinds of strange and weird projects all over the bedroom I shared with my brother, much to the consternation of my Mom, who at one time threatened never to set foot in our room until I got all those scary things cleaned up from the floor under the bed. More than once, I blew a fuse plugging one cockamamie thing or another into the wall. Note, I said fuse, not circuit breaker. Replacing those fuses became quite a drain on my meager allowance but I was happy to pay the price. As I look back across all those contraptions I think the weirdest and the most interesting one I ever built was a razor blade radio.

The very idea of a radio made from a coil of wire, a pair of headphones, a battery, a pencil lead and a razor blade just sparked my imagination. But one summer, there it was, in all its glory staring up at me from Ziff-Davis’ pages. I was all of 11 or12, so you can imagine my parent’s rolling eyes when I asked Mom for a pencil and the core from a toilet paper roll and Dad for one of his razor blades. I had the wire, paper clip and headphones already so I was good to go. Merrily I went out into the back yard and searched the omni-present woodpile for the perfect board to use as a platform for my home made radio. It had to be just so because this was going to be my crowning glory.

I can understand the skepticism in my family. Not all of my electronic projects worked well, in fact some of them worked not at all. But this one was going to be different. The magazine told the story of how GIs made these radios in their foxholes during the war. If they could do that out in the field, surely I could build one in the comfort of my home.

The coil was the hardest part to make. I carefully unraveled the shellac coated wire from the windings of a burned out motor. I needed a couple of hundred feet. I had just enough before I came to the point in the winding where electricity had burnt through the shellac and burned out the motor. I must have spent hours winding the wire around the cardboard toilet paper roll. Each winding had to lie precisely next to the one before it. Several times it would slip and I would have to unwind it all and start it over again. A small dab of glue held the final winding in place. Next, came the “cat whisker” detector which was made from an unwound paper clip with one end carefully stuck next to the pencil’s lead. These household items now were officially radio parts.

Using thumbtacks, I affixed my perfect coil, the razor blade and the “cat whisker” to the board and wired them to some screws to be used as terminals for the ground, antenna and headphones. The instructions said a battery would make it louder so I used an old 6 volt lantern battery I had around from my Boy Scout lantern. At last it was time to “smoke test” my creation.

I ran a wire under the screen in my window down to the drain pipe outside, there was my ground. A second wire went to the screen itself, there was my antenna. The connection to the battery was the last thing to do. I had my headphones on when I touched the terminal on the battery! “Click” then nothing! Wait, the pencil lead was not touching the razor blade. Carefully I bent the paper clip until contact was made. I could hear static. That was something! The instructions said that I might have to move the lead around the razor blade to find the best spot. Sure enough after some searching, WJAX came booming into my headset. It was a resounding success.

Everyone came running at the sound of my whoops and hollers. They all thought that I was finally electrocuting myself with one of my inventions, but these were shouts of joy and triumph. My razor blade radio worked. It could receive only the one station, the one closest to our house, so there would be no nights listening to rock and roll from my favorite station across town. But that didn’t matter. My zany project worked. I had built my first radio. The first of many radio receivers was working, not to mention the many transmitters that were coming in my future. Oh MY!

1 comment:

  1. Thanks for the post and great tips..even I also think that hard work is the most important aspect of getting success..
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