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more vore14

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  • dkbovaird@aol.com
    I added the series resistors to limit the current into the 74HC240 input pins. I chose 10K since the 74HC240 inputs can tolerate higher voltages than its Vcc
    Message 1 of 4 , Sep 1 11:54 PM
      I added the series resistors to limit the current into the 74HC240 input
      pins. I chose 10K since the 74HC240 inputs can tolerate higher voltages than
      its Vcc supply if its input current is limited to below 20mA.

      Should I get into a circuit description or should I just leave it up to Wilf,
      since he kind of implied that he might comment further on it? The circuit is
      simple enough, the diodes are there to prevent the three caps from conducting
      into each others current drain path, while still allowing each cap to be
      recharged by the solar cell.

      For a 6v solar cell (two 3v cells wired in series) the upper "on" point for
      the motors should be about 3.5v with the voltage drop of the diodes. And the
      lower "off" point should be somewhere around 1.5v.

      Because of the hysterisis of the 74HC14 the only problem with using it with
      the photodiodes like I did is that I don't think it will be too sensitive to
      low light levels to influence its phototropic turning behavior.

      The only other problem I can see is that if the reverse sensor/switch is
      closed (the bot hit something) when the motor driver cap is nearly depleted
      of its charge, the bot will most likely stay stuck for quite a while since
      the solar cell will spend its current trying to recharge the reverse cap(s)
      but I think this is a problem with any solar powered reversing bot, unless
      the motor driver cap has just enough charge left to reverse the bot far
      enough to open up the reverse sensor/switch before it shuts down to recharge.

      dave.
    • dkbovaird@aol.com
      Wilf s original reversing photovore circuit configuration (which I ve attached) should be more sensitive to low light levels shining on the photodiodes.
      Message 2 of 4 , Sep 2 12:06 AM
        Wilf's original "reversing photovore" circuit configuration (which I've
        attached) should be more sensitive to low light levels shining on the
        photodiodes.

        dave.
      • Hank Miller
        What exactly is this thing supposed to do? And do you have a freeformed schematic of it? It looks intereting.Hank ...
        Message 3 of 4 , Sep 2 6:16 AM
          What exactly is this thing supposed to do? And do you have a freeformed
          schematic of it? It looks intereting.Hank


          >From: dkbovaird@...
          >Reply-To: beam@yahoogroups.com
          >To: beam@yahoogroups.com
          >Subject: [beam] more vore14
          >Date: Sun, 2 Sep 2001 02:54:30 EDT
          >
          >I added the series resistors to limit the current into the 74HC240 input
          >pins. I chose 10K since the 74HC240 inputs can tolerate higher voltages
          >than
          >its Vcc supply if its input current is limited to below 20mA.
          >
          >Should I get into a circuit description or should I just leave it up to
          >Wilf,
          >since he kind of implied that he might comment further on it? The circuit
          >is
          >simple enough, the diodes are there to prevent the three caps from
          >conducting
          >into each others current drain path, while still allowing each cap to be
          >recharged by the solar cell.
          >
          >For a 6v solar cell (two 3v cells wired in series) the upper "on" point for
          >the motors should be about 3.5v with the voltage drop of the diodes. And
          >the
          >lower "off" point should be somewhere around 1.5v.
          >
          >Because of the hysterisis of the 74HC14 the only problem with using it with
          >the photodiodes like I did is that I don't think it will be too sensitive
          >to
          >low light levels to influence its phototropic turning behavior.
          >
          >The only other problem I can see is that if the reverse sensor/switch is
          >closed (the bot hit something) when the motor driver cap is nearly depleted
          >of its charge, the bot will most likely stay stuck for quite a while since
          >the solar cell will spend its current trying to recharge the reverse cap(s)
          >but I think this is a problem with any solar powered reversing bot, unless
          >the motor driver cap has just enough charge left to reverse the bot far
          >enough to open up the reverse sensor/switch before it shuts down to
          >recharge.
          >
          >dave.
          ><< vore14.gif >>


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        • dkbovaird@aol.com
          ... schematic of it? It looks intereting.Hank Hi Hank, This thing is supposed to end up as a type of Photovore (a robot that looks for light and then moves
          Message 4 of 4 , Sep 2 9:26 AM
            > What exactly is this thing supposed to do? And do you have a freeformed
            schematic of it? It looks intereting.Hank

            Hi Hank,

            This thing is supposed to end up as a type of Photovore (a robot that looks
            for light and then moves toward the light). My circuit is not finished yet so
            I wouldn't recommend that you try to build it. I tend to post partially
            complete schematics just to illustrate my thinking on possible circuit
            designs and ideas.

            If you haven't seen this site, a good tutorial of a complete and proven
            photovore design is available at Chiu-Yuan Fang's site

            http://www.geocities.com/SouthBeach/6897/photovore.html

            You should be able to find all the information you need to build (and
            troubleshoot, if you need it) a photovore there. I think many BEAMers started
            with Chiu's design as one of their first bots.

            I think you mentioned that your father was helping you previously, I think
            that's great, keep BEAMing, but homework comes first! It will help you build
            better BEAM bots!

            dave.
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