I played with spark transmission for a while modifying an old door bell to
make a very high frequency tone and then using tuned circuits to make it
only perhaps cover half of medium wave. It of course very soon mutated into
an electric shock machine using an old valve filament transformer backwards,
a rectifier etc.
Probably grossly unsafe but we all survived.
Brian

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"Bill Wright" wrote in message
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On 19/04/2019 18:07, Brian Gaff wrote:
Can one still get pp1, pp4 and pp9 batteries by the way?
PP1 were six volt press stud, pp4 round but 9 v press stud either end and
pp9 big 9v for good portable radios.
Also looking for the bijou battery since its used in a vintage torch.
Brian


Someone I know well used to trespass on the main East Coast line during
the late 1950 and early 1960s, looking for things to steal. One thing he
found (by smashing a padlock) was a large number of very large 1.5V cells.
They had screw terminals and were connected in series. They were black,
rectangular, about 3" x 3" x 10". They were very heavy but the boy managed
to carry a lot of them home, where he used them to power his spark
transmitter.

Bill