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1st symet attempt

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  • wendall_dogman
    Hi all, I m new to all of this, and have breadboaded together an FLED solar engine for a symet based on the Junkbots book. And of course, if it was working, I
    Message 1 of 10 , Nov 2, 2007
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      Hi all,

      I'm new to all of this, and have breadboaded together an FLED solar
      engine for a symet based on the Junkbots book. And of course, if it
      was working, I wouldn't have to post here and start asking questions.
      You can see the schematic for this at
      http://www.solarbotics.net/library/circuits/se_t1_fled.html.

      All parts are Radio Shack. The motor is rated at 1.5-3.0V, and
      plugging it directly into a 1.5V charge makes it spin up fine. The
      2N3906 in a Radio Shack transistor marked "National 1069015A"-- the
      box said "2N3906" at Radio Shack, hope it is the right thing. The
      other transistor is definatly a 3904-- says so right on the part.

      I have tried to copy exactly the breadboard photo in the book, have
      rebuilt it several times, etc. I've tried using a little solar panel
      from Radio Shack, and when that didn't work, I added a constant 1.5V
      charge to it in case the panel wasn't putting out enough juice to do
      anything. Even with 1.5V there is no activity. Again, I'm very
      limited on my understanding on electronics, so I hope I am making
      valid measurements, etc. in my diagnosis below . . .

      My power source puts out about 1.285 actual volts. I can measure
      voltage across the outputs of the caps and ground, so I don't think
      I've got them in backwards or blown them yet. I have the full 1.285V
      going into the 3906's emitter and I can measure 1.2V at the base. If
      I measure directly across from the emitter to the collector I can see
      a 0.61V charge, but if I measure from the collector to ground I get
      0V. That's about how far I've traced this before I get confused, and
      I'd love to know what the next thing I should test or check out would
      be . . . One last thing I've noticed is that if I up the Voltage from
      1.5 to 3.0 my FLED begins to blink, so at least I haven't burned that
      out yet, either. Anyway, any input would be greatly appreciated.
      This is my 3rd attempt on building a symet in a year, and I'd like to
      actually get it working this time around!
    • chhstaffer
      ... questions. ... panel ... 1.285V ... If ... see ... and ... would ... from ... that ... to ... Have you tried adjusting the resistor values? in the
      Message 2 of 10 , Nov 2, 2007
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        --- In beam@yahoogroups.com, "wendall_dogman" <wendall_dogman@...>
        wrote:
        >
        > Hi all,
        >
        > I'm new to all of this, and have breadboaded together an FLED solar
        > engine for a symet based on the Junkbots book. And of course, if it
        > was working, I wouldn't have to post here and start asking
        questions.
        > You can see the schematic for this at
        > http://www.solarbotics.net/library/circuits/se_t1_fled.html.
        >
        > All parts are Radio Shack. The motor is rated at 1.5-3.0V, and
        > plugging it directly into a 1.5V charge makes it spin up fine. The
        > 2N3906 in a Radio Shack transistor marked "National 1069015A"-- the
        > box said "2N3906" at Radio Shack, hope it is the right thing. The
        > other transistor is definatly a 3904-- says so right on the part.
        >
        > I have tried to copy exactly the breadboard photo in the book, have
        > rebuilt it several times, etc. I've tried using a little solar
        panel
        > from Radio Shack, and when that didn't work, I added a constant 1.5V
        > charge to it in case the panel wasn't putting out enough juice to do
        > anything. Even with 1.5V there is no activity. Again, I'm very
        > limited on my understanding on electronics, so I hope I am making
        > valid measurements, etc. in my diagnosis below . . .
        >
        > My power source puts out about 1.285 actual volts. I can measure
        > voltage across the outputs of the caps and ground, so I don't think
        > I've got them in backwards or blown them yet. I have the full
        1.285V
        > going into the 3906's emitter and I can measure 1.2V at the base.
        If
        > I measure directly across from the emitter to the collector I can
        see
        > a 0.61V charge, but if I measure from the collector to ground I get
        > 0V. That's about how far I've traced this before I get confused,
        and
        > I'd love to know what the next thing I should test or check out
        would
        > be . . . One last thing I've noticed is that if I up the Voltage
        from
        > 1.5 to 3.0 my FLED begins to blink, so at least I haven't burned
        that
        > out yet, either. Anyway, any input would be greatly appreciated.
        > This is my 3rd attempt on building a symet in a year, and I'd like
        to
        > actually get it working this time around!
        >
        Have you tried adjusting the resistor values?
        in the debugging notes in the book junkbots they say "if you hear
        a high-pitched whine from the motor the solarengine is having trouble
        latching on. Find a lower-value resistor and swap it into the
        circuit."
      • Joseph Charles
        Hi Wendall, You don t have a high enough supply voltage. You ll need around 3 volts for the circuit to fire. This includes the turn-on voltage of the FLED and
        Message 3 of 10 , Nov 2, 2007
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          Hi Wendall,

          You don't have a high enough supply voltage. You'll need around 3
          volts for the circuit to fire. This includes the turn-on voltage of
          the FLED and the PNP transistor.

          When the FLED flashes, brief spikes of current flow through the motor
          winding and the base resistor. Current through a resistance causes a
          voltage to appear across the resistance. The motor winding and the
          resistor are in series across the base/emitter junction of the PNP
          transistor. When the voltage across the base/emitter approaches around
          0.5V, the PNP transistor starts to turn on.

          When the PNP begins to turn on, it starts turning on the NPN, which
          makes the PNP turn on harder, which makes the NPN turn on harder...and
          we're off and away.

          A blinking FLED, without motor movement, is leaking charge from the
          storage capacitor. If your FLED just blinks away with no motor
          movement, try raising the resistor value. This will generate a higher
          voltage, across the base/emitter of the PNP, for the same current
          through the FLED, increasing the chances of turn on. I wouldn't go
          much higher than 10k, though, but feel free to experiment.

          Hope that helps.

          Cheers,

          Jo


          --- In beam@yahoogroups.com, "wendall_dogman" <wendall_dogman@...> wrote:
          >
          > Hi all,
          >
          > I'm new to all of this, and have breadboaded together an FLED solar
          > engine for a symet based on the Junkbots book. And of course, if it
          > was working, I wouldn't have to post here and start asking questions.
        • wendall_dogman
          Hi all, thanks for your help. I hooked up a 10K pot in place of the 2.2K resistor and after a little tweaking got the motor to start spinning while pushing 3V
          Message 4 of 10 , Nov 3, 2007
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            Hi all, thanks for your help. I hooked up a 10K pot in place of the
            2.2K resistor and after a little tweaking got the motor to start
            spinning while pushing 3V into the circuit! My guess is that the
            resistance is around 8K or so, I'll measure it shortly to find out for
            sure.

            Now I see the issue with the "latching" bit. It seems like the motor
            makes about a 1/8 turn each pulse but sometimes it gets stuck and
            won't turn until you manually twist the shaft of the motor a bit.
            Would using a smaller motor help this? I have a tape deck motor which
            appears to be smaller than what I'm working with now. I was hoping to
            save it for a solar roller, but I could use it now if it would work
            better . . . I have a number of these Radio Shack motors if swapping
            one out for another might help.

            So I need more solar panels to do this right than my one little Radio
            Shack job. Will I need something that will put out 3V consistantly,
            like the current that I'm currently feeding it? That seems like that
            would be a lot of Radio Shack solar panels.

            Finally, I think I have read that the FLED is not supposed to flash?
            Mine is flashing . . . that's ok, right?

            Thanks again for the help, it is really great to see the 1st twitch of
            a solar engine come to life, even if it's not really solar powered yet
            . . .
          • wendall_dogman
            Hi all, I m looking into solar cells to power this symet. The standard Radio Shack silicon solar panel produces 0.4 amps at 0.55VDC in full sunlight
            Message 5 of 10 , Nov 5, 2007
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              Hi all, I'm looking into solar cells to power this symet. The
              standard Radio Shack silicon solar panel produces "0.4 amps at 0.55VDC
              in full sunlight" according to the packaging. In re-reading the symet
              chapter in Junkbots, I see that I need something "capable of producing
              at least 3V". So I guess my question is how do I arrange a minimum of
              6 of these cells on top of my symet, or better yet, what kind of solar
              cells should I be looking for that can actually produce 3V? Is
              Solarbotics about the only site with decently powerful solar panels?
              And is there anywhere with cheaper ones that would still be adequate
              for powering a symet or other beam robot?

              Another question is whether amperage matters-- my limited
              understanding of electronics tells me that higher amps would cause the
              FLED solar engine to activate more frequently, as it would cause the
              caps to charge more quickly. Is this correct? While it's connected
              to batteries right now, it activates every second, which is due to the
              FLED from what I've read. Does this happen because the batteries can
              produce enough amps to fully charge the caps in less than a second, so
              there is plenty of juice for the FLED to do it's thing when it's one
              second timer goes off every time?

              Finally, will bigger caps mean a faster spin or a longer spin each
              time the solar engine fires?

              Sorry for all the simple questions, once I get this straight in my
              head I'm sure I'll be able to ask more intelligent things later.
            • wendall_dogman
              Ok, I was reading my pot wrong in the post below-- instead of 8K resistance it was only 2.62. Sorry if that figure freaked anyone out.
              Message 6 of 10 , Nov 5, 2007
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                Ok, I was reading my pot wrong in the post below-- instead of 8K
                resistance it was only 2.62. Sorry if that figure freaked anyone out.

                --- In beam@yahoogroups.com, "wendall_dogman" <wendall_dogman@...> wrote:
                >
                > Hi all, thanks for your help. I hooked up a 10K pot in place of the
                > 2.2K resistor and after a little tweaking got the motor to start
                > spinning while pushing 3V into the circuit! My guess is that the
                > resistance is around 8K or so, I'll measure it shortly to find out for
                > sure.
              • Robotics in Motion
                Good afternoon, Another source would be my store located at www.roboticsinmotion.com. Check it out. Regards, Kevin Wells, Owner www.roboticsinmotion.com ...
                Message 7 of 10 , Nov 5, 2007
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                  Good afternoon,
                   
                  Another source would be my store located at www.roboticsinmotion.com.  Check it out.
                   
                  Regards,
                   
                  Kevin Wells, Owner
                  ----- Original Message ----
                  From: wendall_dogman <wendall_dogman@...>
                  To: beam@yahoogroups.com
                  Sent: Monday, November 5, 2007 4:15:26 PM
                  Subject: [beam] Re: 1st symet attempt

                  Hi all, I'm looking into solar cells to power this symet. The
                  standard Radio Shack silicon solar panel produces "0.4 amps at 0.55VDC
                  in full sunlight" according to the packaging. In re-reading the symet
                  chapter in Junkbots, I see that I need something "capable of producing
                  at least 3V". So I guess my question is how do I arrange a minimum of
                  6 of these cells on top of my symet, or better yet, what kind of solar
                  cells should I be looking for that can actually produce 3V? Is
                  Solarbotics about the only site with decently powerful solar panels?
                  And is there anywhere with cheaper ones that would still be adequate
                  for powering a symet or other beam robot?

                  Another question is whether amperage matters-- my limited
                  understanding of electronics tells me that higher amps would cause the
                  FLED solar engine to activate more frequently, as it would cause the
                  caps to charge more quickly. Is this correct? While it's connected
                  to batteries right now, it activates every second, which is due to the
                  FLED from what I've read. Does this happen because the batteries can
                  produce enough amps to fully charge the caps in less than a second, so
                  there is plenty of juice for the FLED to do it's thing when it's one
                  second timer goes off every time?

                  Finally, will bigger caps mean a faster spin or a longer spin each
                  time the solar engine fires?

                  Sorry for all the simple questions, once I get this straight in my
                  head I'm sure I'll be able to ask more intelligent things later.




                  Be smarter than spam. See how smart SpamGuard is at giving junk email the boot with the All-new Yahoo! Mail
                • Joseph Charles
                  Hi Wendall, You are pretty much on track with your understanding of amps and capacitors. The Radio Shack solar panels are not really suitable because, as you
                  Message 8 of 10 , Nov 6, 2007
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                    Hi Wendall,

                    You are pretty much on track with your understanding of amps and
                    capacitors.

                    The Radio Shack solar panels are not really suitable because, as you
                    have noted, you'll need quite a few to achieve the voltage you need.

                    Higher voltage types seem to generally produce a smaller current, but
                    that's why the SE came about in the first place: to store the charge
                    until it can usefully dump it through the motor.

                    Larger caps will mean a longer spin for your motor.

                    Jo


                    --- In beam@yahoogroups.com, "wendall_dogman" <wendall_dogman@...> wrote:

                    >
                    > Finally, will bigger caps mean a faster spin or a longer spin each
                    > time the solar engine fires?
                  • Joseph Charles
                    I was extremely worried.
                    Message 9 of 10 , Nov 6, 2007
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                      I was extremely worried.

                      --- In beam@yahoogroups.com, "wendall_dogman" <wendall_dogman@...> wrote:
                      >
                      > Ok, I was reading my pot wrong in the post below-- instead of 8K
                      > resistance it was only 2.62. Sorry if that figure freaked anyone out.
                    • wilf_nv
                      Argh! Huh? Phew! ... out.
                      Message 10 of 10 , Nov 6, 2007
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                        Argh! Huh? Phew!

                        > --- In beam@yahoogroups.com, "wendall_dogman" <wendall_dogman@> wrote:
                        > >
                        > > Ok, I was reading my pot wrong in the post below-- instead of 8K
                        > > resistance it was only 2.62. Sorry if that figure freaked anyone
                        out.
                        >
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