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Best light-charging, dark turn-on circuit?

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  • chartres456
    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
    Message 1 of 5 , 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:
      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
    • wilf_nv
      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
      Message 2 of 5 , Dec 1, 2007
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        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
        >
      • chartres456
        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
        Message 3 of 5 , Dec 2, 2007
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          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!

          Chris



          --- 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
          > >
          >
        • wilf_nv
          couple of problems conspire against solarizing the FIFO. 1) The FIFO LED peak current (30ma) on time is 100x longer than the pummer current pulse. 2) The FIFO
          Message 4 of 5 , Dec 2, 2007
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            couple of problems conspire against solarizing the FIFO.

            1) The FIFO LED peak current (30ma) on time is 100x longer than the
            pummer current pulse.
            2) The FIFO does not provide inherent output drive voltage doubling.
            3) The FIFO two series 1.5F aerogel caps = 0.75F
            4) The FIFO circuit has a narrower operating range.

            Since the FIFO was designed for 5V and the average current of the
            circuit is 15ma (please measure), four or five 170mah NiCd batteries
            in series (4.8V) should work for at least several hours. You can add
            a resistor in series with the LED to lower the brightness and average
            current.

            I can optimize the FIFO circuit for lower voltage (3.6V) operation
            using a cmos opamp.

            The SE driver (74AC240) can be combined with the opamp and used as
            the PWM controlled voltage doubling LED driver and to turn the FIFO
            on intermittently to extend battery life.

            Remember the charm of the FIFO circuit is its simplicity and the
            unusual fade in fade out pattern but not its efficiency.

            wilf





            --- In beam@yahoogroups.com, "chartres456" <chartres456@...> wrote:
            >
            > 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!
            >
            > Chris
            >
            >
            >
            > --- 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
            > > >
            > >
            >
          • chartres456
            Wilf, I appreciate your educating me on the virtues and limitations of the FIFO circuit. A reminder of the need for parsimony when placing demands on solar
            Message 5 of 5 , Dec 3, 2007
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              Wilf,

              I appreciate your educating me on the virtues and limitations of the
              FIFO circuit. A reminder of the need for parsimony when placing
              demands on solar engines.

              Thinking in an opposite, and perhaps heretically non-beamish,
              direction, we all have a surplus of 5V DC energy available at our
              desks, often close to where our robots reside.

              Have you seen or developed circuits that could use the USB ports on
              our desktop computers to a) drive a flasher or other load, or b)
              charge a compact ni/cad or lithium rechargeable that's incorporated in
              the 'bot design? (Web searches, surprisingly, haven't yielded credible
              circuits. One might have to purchase and dismantle one of the silly
              USB-powered toys that are widely offered.)

              It seems one would want to incorporate a form of isolation to avoid
              frying the computer if there was a flaw in the peripheral...

              Wilf, thanks for your instructive responses.

              Chris

              p.s. A couple of inspirations for charging batteries via USB found on
              the web:

              http://www.usbcell.com/ (I've got two of the AAs powering my cordless
              mouse - they work flawlessly)

              The USB Cell people look as if they're developing a USB-charged 3.6V
              phone and device battery that we might find useful; in the meantime I
              found a couple of alternatives:
              http://www.dealextreme.com/details.dx/sku.7067
              http://www.dealextreme.com/details.dx/sku.3060

              Would be interesting to see if these would make interesting platforms
              for both stationary and mobile devices, but it would also be useful to
              adapt other charging circuits (several of which depend on wall-wart
              transformers) for USB input.




              --- In beam@yahoogroups.com, "wilf_nv" <wrigter@...> wrote:
              >
              > couple of problems conspire against solarizing the FIFO.
              >
              > 1) The FIFO LED peak current (30ma) on time is 100x longer than the
              > pummer current pulse.
              > 2) The FIFO does not provide inherent output drive voltage doubling.
              > 3) The FIFO two series 1.5F aerogel caps = 0.75F
              > 4) The FIFO circuit has a narrower operating range.
              >
              > Since the FIFO was designed for 5V and the average current of the
              > circuit is 15ma (please measure), four or five 170mah NiCd batteries
              > in series (4.8V) should work for at least several hours. You can add
              > a resistor in series with the LED to lower the brightness and average
              > current.
              >
              > I can optimize the FIFO circuit for lower voltage (3.6V) operation
              > using a cmos opamp.
              >
              > The SE driver (74AC240) can be combined with the opamp and used as
              > the PWM controlled voltage doubling LED driver and to turn the FIFO
              > on intermittently to extend battery life.
              >
              > Remember the charm of the FIFO circuit is its simplicity and the
              > unusual fade in fade out pattern but not its efficiency.
              >
              > wilf
              >
              >
              >
              >
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