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RE: [beam] SC-head

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  • Wilf Rigter
    I m sure everyone s had a good laugh over CShead-v3 but overlooking that it only twitches when you shine a light in its eyes, it also requires less power than
    Message 1 of 16 , Nov 6, 2001
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      I'm sure everyone's had a good laugh over CShead-v3 but overlooking that it
      only twitches when you shine a light in its eyes, it also requires less
      power than most other head circuits. Just kidding, note the extra inverter
      where the sun don't shine and much better now, thank you, in the attached
      CShead3corrected.gif . But the silver lining is that the uncorrected version
      had a big vacuum between PD1 and PD2 just waiting for a deadband diode: ergo
      CSheadv4.gif - untested until tonight but it doesn't get much simpler! The
      diode may be replaced with another PD, forward or backward biased, pointing
      to the back of the head for more complex behavior.

      wilf

      -----Original Message-----
      From: Wilf Rigter
      Sent: Tuesday, November 06, 2001 12:35 AM
      To: Wilf Rigter; ''R. Martin Keen ' '; ''beam@yahoogroups.com ' '
      Cc: ''beam@yahoogroups.com ' '
      Subject: RE: [beam] SC-head



      Works great! Well only after fiddling with it. The 1M + 1M combination was
      a dead wrong suggestion. But 1M in series and 4M in parallel with the
      schmitt trigger and 1000 pf to ground works but is sesnitive to light
      level. I tried your original design with 100pf in parallel with the schmitt
      trigger and got a lot of oscillation. An easy test for efficiency of the
      circuit is to measure current with no motor attached. With Vcc=5V and the
      light balanced, if the current is more than 3mA then the circuit must be
      oscillating. I measured 18mA with the parallel capacitor.

      I have not tried many variations on your SC circuit nor have I build the
      whole head assembly but the attached circuit seems to work well on a
      protoboard with a pair of insensitive PDs and driving a small gear motor. I
      replaced the series resistor with two parallel diodes to make the circuit
      less sensitive to variations in light. If you add 10M resistors in parallel
      with the PDs the circuit powers down to a few mA with very low light.

      I will build the SC head circuit/assembly and test it as a unit.

      wilf

      -----Original Message-----
      From: Wilf Rigter
      To: 'R. Martin Keen '; 'beam@yahoogroups.com '
      Cc: 'beam@yahoogroups.com '
      Sent: 11/5/01 10:01 PM
      Subject: RE: [beam] SC-head

      Yes, "unusual" is a compliment. No luck, eh? Interesting! I'll play with
      it and report back.

      wilf

      -----Original Message-----
      From: R. Martin Keen
      To: beam@yahoogroups.com
      Cc: beam@yahoogroups.com
      Sent: 11/5/01 9:08 PM
      Subject: [beam] SC-head

      Thank you, Wilf. I'll take 'unusual' as a compliment, after seeing your
      NuRing circuit.

      I bread boarded the new design, and it didn't really work. When a
      photodiode is shorted out, it make a nice bistable flip flop. I tested
      several different arrangements without luck. I hope someone else will
      try.
    • R. Martin Keen
      Thank you Wilf, Bruce, and Dave! I was wrong about the size of the capacitor. I thought it was 220 pF, but it is .022 uF. The capacitor said 22 (underlined),
      Message 2 of 16 , Nov 6, 2001
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        Thank you Wilf, Bruce, and Dave!

        I was wrong about the size of the capacitor. I thought it was 220 pF,
        but it is .022 uF. The capacitor said 22 (underlined), with a white spot
        on top.
        It has very quirky behavior. The original head would turn toward the
        light (duh), but stop 10 degrees early. Fifteen seconds later it turns
        five degrees closer. A minute later it moves another 5 degrees, and
        stops. Dunno why this happens, but it is fun to watch.

        I've kinda got the solar part working. I'm trying to cut down on parts
        right now, but a circuit should be out tomorrow!

        -Martin

        THE resource for beginners
        http://beamlinks.botic.com
        "The best of everyone's BEAM"




        On Tue, 6 Nov 2001 00:35:22 -0800 Wilf Rigter
        <wilf.rigter@...> writes:
        >
        > Works great! Well only after fiddling with it. The 1M + 1M
        > combination was
        > a dead wrong suggestion. But 1M in series and 4M in parallel with
        > the
        > schmitt trigger and 1000 pf to ground works but is sesnitive to
        > light
        > level. I tried your original design with 100pf in parallel with the
        > schmitt
        > trigger and got a lot of oscillation. An easy test for efficiency of
        > the
        > circuit is to measure current with no motor attached. With Vcc=5V
        > and the
        > light balanced, if the current is more than 3mA then the circuit
        > must be
        > oscillating. I measured 18mA with the parallel capacitor.
        >
        > I have not tried many variations on your SC circuit nor have I build
        > the
        > whole head assembly but the attached circuit seems to work well on a
        > protoboard with a pair of insensitive PDs and driving a small gear
        > motor. I
        > replaced the series resistor with two parallel diodes to make the
        > circuit
        > less sensitive to variations in light. If you add 10M resistors in
        > parallel
        > with the PDs the circuit powers down to a few mA with very low
        > light.
        >
        > I will build the SC head circuit/assembly and test it as a unit.
        >
        > wilf
        >
        > -----Original Message-----
        > From: Wilf Rigter
        > To: 'R. Martin Keen '; 'beam@yahoogroups.com '
        > Cc: 'beam@yahoogroups.com '
        > Sent: 11/5/01 10:01 PM
        > Subject: RE: [beam] SC-head
        >
        > Yes, "unusual" is a compliment. No luck, eh? Interesting! I'll play
        > with
        > it
        > and report back.
        >
        > wilf
        >
        > -----Original Message-----
        > From: R. Martin Keen
        > To: beam@yahoogroups.com
        > Cc: beam@yahoogroups.com
        > Sent: 11/5/01 9:08 PM
        > Subject: [beam] SC-head
        >
        > Thank you, Wilf. I'll take 'unusual' as a compliment, after seeing
        > your
        > NuRing circuit.
        >
        > I bread boarded the new design, and it didn't really work. When a
        > photodiode is shorted out, it make a nice bistable flip flop. I
        > tested
        > several different arrangements without luck. I hope someone else
        > will
        > try.
        >
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