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Old 11th Jan 2011, 2:02 pm   #4
kalee20
Dekatron
 
Join Date: Feb 2007
Location: Lynton, N. Devon, UK.
Posts: 7,059
Default Re: Battery-less audio amplifier

Both these approaches have this in common - they use EM energy from another source to provide power. Only Herald1360's approach uses energy from somewhat further up in the frequency spectrum.

Of course, to keep on-topic, you could only use one solar cell, else you'd have a (solar) battery.

Micropower operation is fascinating, however I'd guess that the micropower op-amp could not drive more than a crystal earpiece without significantly increasing its power demand.
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