55958Re: FullSpeed Dozer
- Jun 2, 2007--- In email@example.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
> fair difference in light levels on each of the PD's in order toreact.
> If it went into a less well-lit part of the room, it basicallybecame
> a bit 'visually impaired' and just chugged around, not reactingwhen I
> shaded a PD. I had to make one PD very much darker than the otherone
> to get a reaction.it
> 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 offun
> 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.I'll try swapping out the IR LEDs for PRs insted with the 1K
> 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.
> Hi Jo.
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
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 firstname.lastname@example.org, "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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