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Old 12th Jan 2011, 11:18 am   #10
davegsm82
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Join Date: Jan 2004
Location: Blyth, Northumberland, UK.
Posts: 858
Default Re: Battery-less audio amplifier

I've tried to do this before, it never worked particularly well.

In the early 90's (possibly late 80's?) I made a crystal radio from some old cheap chinese AM transistor radio, I put a battery snap (pp3) on the earth and connected this to the radiator. I was astounded to find it didn't need an aerial! The ferrite rod inside was enough. Used to listen to Radio1 on that late into the night, until I got bored or fell asleep and rolled my ear over onto one of those horrible crystal earpieces!

Interestingly, now that I have my own home i've been experimenting more, when I moved in we removed the old gas fire but left the aluminium flue in place, this is insulated from everything by brickwork. Measured with a fluke 175 there is about 500mV DC with respect to earth on it at all times, even after breifly shorting it out. Works quite well as a CB aerial too!

Have a look here, from what I can tell, these crazy russians aren't playing with a live transmitter, they're playing with a disused antenna not far from a transmitter, just look at that spark!...

http://englishrussia.com/index.php/2...-plasma-radio/

Dave.
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