Loading ...
Sorry, an error occurred while loading the content.
 

Re: Question about wilf Rirter's phototropic 2-motor walker schematic

Expand Messages
  • wilf_nv
    Hi Charley, can you post a link to the schematic, thanks wilf ... makes ... run ... is
    Message 1 of 7 , Jun 30, 2008
      Hi Charley,

      can you post a link to the schematic,

      thanks

      wilf


      --- In beam@yahoogroups.com, "rameses32" <rameses32@...> wrote:
      >
      > I built this circuit But I have a question about the photo bridge
      > buffer, the enable pin in the schematic is tied to high, and this
      makes
      > the output high-Z, and the walker is not phototropic, but when I
      run
      > the enable pin to ground the robot becomes phototropic, my question
      is
      > should it go straight to ground? or through a resistor or connect
      > somewhere else?
      > Charley
      >
    • rameses32
      http://www.solarbotics.net/library/circuits/bot_walker_phototrope.html Have a look at the 74HC125 at the photo-bridge, the enable pin goes to VCC, making the
      Message 2 of 7 , Jul 1, 2008
        http://www.solarbotics.net/library/circuits/bot_walker_phototrope.html

        Have a look at the 74HC125 at the photo-bridge, the enable pin goes
        to VCC, making the output high Z.

        Charley




        --- In beam@yahoogroups.com, "wilf_nv" <wrigter@...> wrote:
        >
        > Hi Charley,
        >
        > can you post a link to the schematic,
        >
        > thanks
        >
        > wilf
        >
        >
        > --- In beam@yahoogroups.com, "rameses32" <rameses32@> wrote:
        > >
        > > I built this circuit But I have a question about the photo bridge
        > > buffer, the enable pin in the schematic is tied to high, and this
        > makes
        > > the output high-Z, and the walker is not phototropic, but when I
        > run
        > > the enable pin to ground the robot becomes phototropic, my
        question
        > is
        > > should it go straight to ground? or through a resistor or connect
        > > somewhere else?
        > > Charley
        > >
        >
      • S
        It also seems the diodes in the Motor Drivers are backwards. At least according to this anyway:
        Message 3 of 7 , Jul 1, 2008
          It also seems the diodes in the Motor Drivers are backwards. At least according to this anyway:


          rameses32 <rameses32@...> wrote:
          http://www.solarbot ics.net/library/ circuits/ bot_walker_ phototrope. html

          Have a look at the 74HC125 at the photo-bridge, the enable pin goes
          to VCC, making the output high Z.

          Charley

          --- In beam@yahoogroups. com, "wilf_nv" <wrigter@... > wrote:
          >
          > Hi Charley,
          >
          > can you post a link to the schematic,
          >
          > thanks
          >
          > wilf
          >
          >
          > --- In beam@yahoogroups. com, "rameses32" <rameses32@> wrote:
          > >
          > > I built this circuit But I have a question about the photo bridge
          > > buffer, the enable pin in the schematic is tied to high, and this
          > makes
          > > the output high-Z, and the walker is not phototropic, but when I
          > run
          > > the enable pin to ground the robot becomes phototropic, my
          question
          > is
          > > should it go straight to ground? or through a resistor or connect
          > > somewhere else?
          > > Charley
          > >
          >


        • Joseph Charles
          The circuit you reference uses NPN input transistors. The two-motor walker H-bridges use PNP input transistors. ...
          Message 4 of 7 , Jul 1, 2008
            The circuit you reference uses NPN input transistors.

            The two-motor walker H-bridges use PNP input transistors.


            --- In beam@yahoogroups.com, S <garvinguy@...> wrote:
            >
            > It also seems the diodes in the Motor Drivers are backwards. At
            least according to this anyway:
            >
            http://f1.grp.yahoofs.com/v1/QBxqSAwD1LX4pBNME-YZNAgNbRIlbN-0yIvy7GSLugrKOcoKEDXuXTglfPTSJDEmqLXpNvdN7QFKLU1FJzFViXWi1dFthg/smoke%20proof%20Hbridge.gif
            >
          • S
            Ahh you re right. Thought I checked that. Joseph Charles wrote: The circuit you reference uses NPN input transistors. The
            Message 5 of 7 , Jul 1, 2008
              Ahh you're right.  Thought I checked that.

              Joseph Charles <jodicalhon@...> wrote:
              The circuit you reference uses NPN input transistors.

              The two-motor walker H-bridges use PNP input transistors.

              --- In beam@yahoogroups. com, S <garvinguy@. ..> wrote:
              >
              > It also seems the diodes in the Motor Drivers are backwards. At
              least according to this anyway:
              >
              http://f1.grp. yahoofs.com/ v1/QBxqSAwD1LX4p BNME-YZNAgNbRIlb N-0yIvy7GSLugrKO coKEDXuXTglfPTSJ DEmqLXpNvdN7QFKL U1FJzFViXWi1dFth g/smoke%20proof% 20Hbridge. gif
              >


            • wilf_nv
              You are absolutely right Charley, the photobridge PWM oscillator 74HC125 buffer enable pin should be connected to ground (not to Vcc as shown). Alternately
              Message 6 of 7 , Jul 1, 2008
                You are absolutely right Charley,

                the photobridge PWM oscillator 74HC125 buffer enable pin should be
                connected to ground (not to Vcc as shown).

                Alternately connect that enable pin to same point as the microcore
                74HC125 enable signal. By making the latter connection, it makes the
                circuit operation a bit more complex and possibly more difficult to
                troubleshoot. That is only justified if stopping the optical bridge
                controlled PWM oscillator will reduce the standby current when bright
                light is detected and the walker is "basking" in a bright light pool.

                Just to remind you, the purpose of the PWM oscillator is to change
                the timing of the microcore to turn the walker towards the light
                source. When the microcore is disabled, the PWM oscillator has no
                effect anyway and just wastes power. How much power? You will need
                to measure it to find out if it is significant compared to the
                charging current of the solar cells.

                The 2 diodes in each h-bridge are included to avoid "smoke" that can
                occur if both inputs of the h-bridge go low at the same time.

                Can you say oops?

                Thanks for your feedback and keep us updated on your progress!

                wilf


                --- In beam@yahoogroups.com, "rameses32" <rameses32@...> wrote:
                >
                >
                http://www.solarbotics.net/library/circuits/bot_walker_phototrope.html
                >
                > Have a look at the 74HC125 at the photo-bridge, the enable pin goes
                > to VCC, making the output high Z.
                >
                > Charley
                >
                >
                >
                >
                > --- In beam@yahoogroups.com, "wilf_nv" <wrigter@> wrote:
                > >
                > > Hi Charley,
                > >
                > > can you post a link to the schematic,
                > >
                > > thanks
                > >
                > > wilf
                > >
                > >
                > > --- In beam@yahoogroups.com, "rameses32" <rameses32@> wrote:
                > > >
                > > > I built this circuit But I have a question about the photo
                bridge
                > > > buffer, the enable pin in the schematic is tied to high, and
                this
                > > makes
                > > > the output high-Z, and the walker is not phototropic, but when
                I
                > > run
                > > > the enable pin to ground the robot becomes phototropic, my
                > question
                > > is
                > > > should it go straight to ground? or through a resistor or
                connect
                > > > somewhere else?
                > > > Charley
                > > >
                > >
                >
              Your message has been successfully submitted and would be delivered to recipients shortly.