From: Jonathan Kirwan
Subject: Re: Crystal radio
X-Newsreader: Forte Agent 1.92/32.572
NNTP-Posting-Date: Sun, 29 Sep 2002 01:24:42 GMT
Organization: AT&T Broadband
Date: Sun, 29 Sep 2002 01:24:42 GMT
On Sat, 28 Sep 2002 21:38:35 GMT, Chuck Simmons
>The canonical crystal set was made from a variable capacitor, a coil, an
>ear piece from a telephone, a safety pin and a galena.
The galena crystal I placed in molten lead and cooled it.
>construction was critical. The nails used as terminals had to be nearly
>rust free. The coil had to be wound on a dur-dur.
And here I'd always thought it was spelled der-der. ;)
>In case you don't
>know, a dur-dur is the cardboard tube inside a roll of toilet paper or
>paper towels. The technical name, dur-dur, derives from the fact that
>when you were five, you probably marched around the house with one of
>these pressed to your mouth saying "dur-dur-dur-dur-...-dur."
Same story I'd heard. hehe.
>pinch, an iron pyrite will work in place of a galena.
Hmm. Never tried that. Given my ignorance, it sounds possible. Did
you actually try some iron pyrite?
>The base is,
>naturally enough, a board. The Dave Berry article, "How to Make a
>Board," explains this well but don't use your board to kill spiders as
>the electrical leakage through spider guts may reduce the performance of
>These radios work best with very long antennas. Do not try to drag the
>wire across your neighbor's roof while he is at home. It's really very
>hard to explain what you are doing and why.
I was running magnet wire all over the place, including from one end
of the roof to the other. That one, in fact, worked pretty good --
until weather combined with my lousy structural design to bring it
>Once the device is assembled you are ready to test it. You will find
>that moving the safety pin point around on the galena or the pyrite is
>more effective at tuning than the capacitor. The capacitor is really for
>looks. After all, whoever heard of a radio without one. Not having the
>capacitor would be like making a 1950s SF movie without a Jacob's
My first jacob's ladder was made from a TV's flyback and hanger wire.
Quickly discovered that I had to be very careful keeping kinks out of
the wire and getting the lacquer abraded off of it.
>Now that your radio is working and you have become adept at tuning, the
>real challenge comes. Finding anything at all worth listening to on
Back then, it was the 50,000 watt (day and night) KEX radio station
for me. Old time radio broadcasts, including lum and abner at the jot
'em down store. With that kick from the station, I could almost run
my room lights -- which is probably why that was the station I usually
listened to, then.