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57076Best light-charging, dark turn-on circuit?

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  • chartres456
    Dec 1, 2007
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      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:

      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!

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