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My first ever radio: a crystal radio kit for my 6'th birthday.
This arrived in a plastic packet containing a three-way terminal
block, 3mm headphone socket, Crystal earpiece, variable capacitor,
glass germanium diode, a small capacitor, 3-inch ferrite rod
and a certain amount of enamelled wire. A few yards of lighting
cable from the local hardware shop was needed for the aerial.
Miraculously I still have part of this radio, as photographed
above, minus the coil and earpiece.
The circuit diagram for this crystal radio is shown below.
The coil was made by winding about 80 turns or so of the enamelled
wire onto the ferrite rod. It is very important to use a high
impedance crystal earpiece (or headphones), not the modern
low impendance moving coil types. With several yards of wire as the
aerial, it was posible to hear some MW radio stations clearly!
Crystal radios make a fantastic introduction to electronics
and radio.
