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Old 12th Jan 2011, 9:32 pm   #11
JHGibson
Retired Dormant Member
 
Join Date: Apr 2003
Location: Salt Spring Island, BC, Canada
Posts: 368
Default Re: Battery-less audio amplifier

Getting back to the original post, reading Ben Tongue's article 25, the procedure seems that you leave the crystal set tuned to a strong local station when the receiver is "off" and the 0.3 Farad cap will charge up. When the crystal set is "Turned on", the now fully charged 0.3 F cap can run the micropower opamp for some 5 hours and that 20 db of gain really helps. 5 hours of listening time is plenty! No need for additional parts like photo voltaic cells.
John.
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