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57088Re: Best light-charging, dark turn-on circuit?

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  • chartres456
    Dec 2, 2007
      Hi, Wilf,

      Thanks for your very helpful suggestion. I grounded all inputs and
      linked all the outputs on the AC240 and it worked first try, first
      tested with battery power and then with the classic pummer SE.

      The challenge now is providing enough SE power. Using a 3733 solar
      cell and either a) two 1.5F 2.75V aerogels in series, or b) a SB
      BattR5 3.6V 170mAh rechargeable Ni-Cad, the pummer only blinks for a
      few minutes on what appears to be a full charge. This in contrast to
      more than half an hour for the "dual LED pummer" from a 2433 and a
      single 1.5F aerogel. Is there a more favorable solarcell/storage
      combination that will extend the activity?

      thanks much for your help!


      --- In beam@yahoogroups.com, "wilf_nv" <wrigter@...> wrote:
      > Hi Chris,
      > The LM358 has a standby current of 1ma so the FIFO circuit will need
      > to be isolated. Use a 74AC240 with a diode and the solar cell
      > connected to the enable lines like the classic pummer SE and tie all
      > outputs connected to drive the FIFO.
      > --- In beam@yahoogroups.com, "chartres456" <chartres456@> wrote:
      > >
      > > Reposting a question that may have gotten buried in the religious
      > > debate of earlier this week....
      > >
      > > A year ago Wilf posted a circuit that makes a highly agreeable fade
      > > in, fade out flasher:
      > > http://tech.groups.yahoo.com/group/beam/message/54701.
      > >
      > > Instead of powering the circuit with batteries, it would be nice to
      > > make it a true pummer: solar cell charge during the day and then
      > turn
      > > on with the requisite voltage at night. This leads to two questions:
      > >
      > > 1. Has anyone compared the various dark turn-on circuits that
      > directly
      > > power the load (as opposed to dropping the trigger on a '240 based
      > > pummer) - Sim D1, SmartCap, Sim D1 v3, etc. to determine which is
      > the
      > > most efficient, most robust, least noisy, with decent hysteresis?
      > >
      > > 2. The FIFO circuit needs higher voltage - at least 4.5V in my
      > hands -
      > > than the standard dark turn-on circuits provide. What's the best
      > solar
      > > cell / storage combination to achieve this higher voltage? Could any
      > > of the above circuits be modified to provide 4.5 volts or more?
      > >
      > > thoughts so far:
      > > a) use a 1F 5.5V capacitor - though that won't provide more than 30
      > > min of decent pumming
      > > b) would it work to charge two 2.5V, 10F capacitors in series for an
      > > effective 5F at 5V?
      > > c) is the optimal power source the 3733 Solarbotics solar cell that
      > > puts out a nominal 6.5 V?
      > > d) is there a battery pack (e.g. Solarbotics BattR10) that could be
      > > paired effectively with one of these charging circuits?
      > >
      > > Any and all advice appreciated!
      > >
      > > Chris
      > >
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