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Old 11th Jan 2011, 12:02 am   #1
JHGibson
Retired Dormant Member
 
Join Date: Apr 2003
Location: Salt Spring Island, BC, Canada
Posts: 368
Default Battery-less audio amplifier

Being a hard-core crystal set builder, I was delighted to read about a battery-less audio amplifier. It used a second crystal set peaked on a local station to charge up a 0.3 FARAD cap. It took most of the day to charge it up to some 1.5 volts , but that was sufficient to run a micropower op amp drawing a microamp for 3 hours.
For details see article 25 on
www.bentongue.com/xtalset/xtalset.html
John.
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