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55958Re: FullSpeed Dozer

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  • jabmechtech
    Jun 2, 2007
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      --- In beam@yahoogroups.com, "Joseph Charles" <jodicalhon@...> wrote:
      > Hi Jab,
      > I've actually come full circle on this.
      > I noticed last night that the 74AC14 full-speed dozer seemed to
      need a
      > fair difference in light levels on each of the PD's in order to
      > If it went into a less well-lit part of the room, it basically
      > a bit 'visually impaired' and just chugged around, not reacting
      when I
      > shaded a PD. I had to make one PD very much darker than the other
      > to get a reaction.
      > I assume the largish hysteresis of the 74AC14 inputs, and the very
      > high resistance of the PD bridge, when darkish, compared to the 10M
      > oscillator resistor, may be at play here. (Could be wrong, though!)
      > I swapped out the PD's for a pair of phototransistors, with current
      > limiting 1k resistors (one for each PT), and the sensitivity was
      > greatly improved.
      > But I looked at the increasing parts count and thought, "Hmmm...".
      > So I breadboarded the original 'waddle' bot (with reverse), and set
      > loose. I've decided I actually prefer the funny little movement of
      > this version, and its sometimes unpredictable reactions, to the more
      > 'souped-up' versions.
      > It think that Wilf's 74AC240 BullDozer circuit won't have the same
      > insensitivity problems that my 74AC14 version had, so it might be
      > to have a go at building that one.
      > This also confirms why I like to use breadboards (and some sort of
      > test base, too). You can chop and change a circuit, and try as many
      > variations as you like, before settling on a final design.
      > Jo
      > Hi Jo.
      I'll try swapping out the IR LEDs for PRs insted with the 1K
      resistorlike you did. But use the Motor drive circuit.I'll also have
      a go at the 2nd circuit with the 330ohm resistor and diode and single
      Mine just spun in one direction unless I plased my hand almost on it
      to shade the eyes then it falowed my hand(like it was hungry for
      fingers) :).
      When I can get some more parts I'll build Wilfs BullDozer.
      Thank you. I have learned so much from this project and had a blast
      doing it. I'm sorry I still don't understand the bread board thing, I
      can't get stuff to work until I build(and Rebuild)it.
      > --- In beam@yahoogroups.com, "jabmechtech" <jabmechtech@> wrote:
      > > I can't build this yet, I'm short on the part count. It seemed to
      > > keep climbing.:(
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