Crystal Sets: General
Crystal sets became widely used in the 1920's with their crystals,
cat's whisker and point contact providing hours of amusement, and that
before the broadcast station was picked up!
The point contact between the crystal and a metal
wire or "cat's whisker" formed a semiconductor junction.
An early design of circuit is shown. Far from ideal, it still provided
reception within a few miles of the transmitter providing the aerial was long enough -
the length of a garden being about right!
Usually galena, lead ore, this provided the semiconductor rectified needed for
the radio "detector". Although the crystal had no magical ability
(just a physical property) this did not stop the manufacturers making some outlandish
claims, see the tins for details!
Some Early Crystal "Tins"
The tins would contain one or more crystals and sometimes a pair of tweezers and
A later crystal in a box, possibly of U.S. origin?
The simplest sets had just a coil to tune to the desired
frequency. With few transmitters around this would work, just, and
had the cost advantage of not needing a variable capacitor.
The Brownie II was of this simple design. The knob at the front
moved a slider along a coil. The closer the slider moved to one end the worse the
Circuits soon began to use a fixed coil with a variable capacitor.
The headphones were of necessity high impedance devices which meant that a crystal
set was essentially for personal use. Ingenious designs appeared to amplify the
The Valve Set
Valve (tube) wireless sets soon became the norm offering signal that all the family
could hear and removing the need for the listener to patiently find the right spot
on the crystal.
The Magic of Crystal Sets
Crystal sets did live on from the 1920's into the 1930's not least because they
were simple, cheap and needed no batteries. Crystal sets were also popular with
the young radio enthusiast as they were so simple to build. In fact crystal sets
are still built by enthusiasts and for educational purpose today.
The crystal set was magical. It allowed a whole audience to gain access to the
exciting new media of the day. Perhaps not unlike the "sets" discovered in the
early 1990's; that gave rise to the internet audience.
A 1920's commercial crystal set can be seen in detail on the radio shelf. More crystal sets can be found in
What was "point contact" ?
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