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A wall-wart alternative
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Posted to alt.home.repair,alt.energy.homepower,misc.consumers.frugal-living
phatty mo
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A wall-wart alternative
wrote:
I finally got tired of replacing the 2 C-cells in a clock with a moving
pendulum, so I measured the current (3 volts at 340 microamps) and built
a charge pump like this, viewed in a fixed font:
0.047 uF @400 V
|| |
-----------||---------------------|------------
|| | | |
| | 3V
120 VAC --- --- to clock
^ _
0.047 uF @400 V | |
|| | |
-----------||-----------------------------------
||
I used two caps in case one shorts and for some ground isolation. The diodes
are 5.1 V zeners ($1.29 for 2 at Radio Shack) to limit the clock voltage if
someone unplugs the batteries. This circuit supplies 390 microamps. I hope
to avoid replacing the batteries until their shelf life runs out in 2012 :-)
This could be useful for lots of low-power stuff, eg smoke detectors.
Nick
Why not a small dc-dc converter,from your main 12/24/48V battery bank..
Safer,and probably more efficient. (takes the inverter out of the
loop,atleast.)
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