When I was 10 years old (55 years ago), I found a child's picture book
in the library that showed a copper penny, a safety pin, and a wire coil
mounted on a piece of wood. I had no particular interest in radio or
science at that time but this book appealed to me. I borrowed the book,
went home and built the radio. My antenna was just a piece of wire on
the floor. The darn thing worked! Now, several decades later I realize
that living across the street from the WALL transmitter helped out a lot
;) But that little book and a single afternoon started me off on the
greatest hobby in the world. I have since tried reconstructing such a
set and never had any luck. It's got to be a real copper penny, the
older and more beat up the better, and the safety pin has to find
exactly the right spot and make contact "just right." Except if you
live across from the transmitter tower in which case you can probably
just go outside and listen to your gutter and downspout junction!
Stan WB2LQF
On Thu, Jul 25, 2013 at 03:52 AM, David Gilbert wrote:
>
Actually, I'm pretty sure the crystal set you are referring to used a
piece of galena (a lead sulphide compound), not germanium (and not
geranium, which is a flower). Early crystal sets used a piece of
springy wire called a "cat whisker" to contact the galena at a
sometimes difficult-to-locate crystal, in essence forming a crude
point contact (i.e., Schottky) diode. The crystals are small but
naturally occurring in the galena. My dad had such a set and I
remember using it when I was about six or seven years old (60 years
ago for me), but by that time actual germanium diodes were available
and my first "real" radio used one of those.
73,
Dave AB7E
On 7/25/2013 12:22 AM, Chuck Smallhouse wrote:
My first experience hearing local AM stations was using an actual
chunk of geranium crystal mounted in a blob of lead, that you'd
traded some of your best agate marbles for, You used the point of a
fine safety pin to scratch around on that chunk of geranium to find
the sweat spot, where the station (s) came in the best into your
headphones. It didn't seem to be the same spot night after night !
You tried to use the longest wire that you could sneak out your
window and up to near the top of the tallest tree in your back yard.
Later if you wanted to separate KVOA (1290) ad KTUC (1400), here in
Tucson, you had to wind a big coil on an empty round oatmeal box, and
try and tune it with a variable capacitor that you'd "rescued" from a
defunct radio. This was all mounted on a "bread board", generally a
short section of a 1x 6" or a 1x 8"pine or redwood board. Terminal
points were metal screws into the board (preferably brass) that the
wires were wrapped around !
Gee, that was well over 70 years ago ! Time sure flies when you are
having fun !
Chuck,. W7CS
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