Allegro Razor Blade Sharpener

[Gordon WParticipant @gordonw]

In my days of crystal sets a good long arial and good earth was essential, all the power supply came from the radio signal. The only essential, had to be paid for, was a high-resistance earphone. Plenty about ex government. Tuning coil on varnished cardboard tube with a slider for tuning, razor blade or real diode and you were away. I am sure signals were more powerful in those days, only long wave and medium to worry about, on long wave you good get broadcasts from all over the world in good conditions.

[jason udallParticipant @jasonudall57142]

ok. on the subject of on unauthodox semi conductors..

zinc oxide diode

flame diode

magnetic amplifiers

 

Edited By jason udall on 29/03/2015 13:52:45

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