Subject:
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Re: Train Depot DCC Update
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Newsgroups:
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lugnet.trains
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Date:
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Wed, 17 Mar 1999 07:04:06 GMT
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Viewed:
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3635 times
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Three mile Island train theme
SteveB
Matthew Bates wrote in message ...
> Hmmm, that's a jolly fine theory, I didn't know such a material existed. • Maybe
> I need to go back and figure out a way to incorporate the disc into the
> modified motor[1]. It would be kind of embarassing if my motor fell out • onto
> the track one day after melting its way through the plastic.
>
> Matt
>
> [1] The disc is held in place by the same piece of metal that picks up the
> supply from the wheels. For a DCC installation these need to be isolated • from
> one another. The only place that I can see to make a cut is the little tab
> that holds the disc onto the motor terminal, but cutting the tab makes the • tab
> and the disc fall out!
>
> > OK, here's my guess. It's a polymer thermal resistive protection device.
> > Put it in circuit, and turn up the power...basically, no resistance.
> > Now, with the power up, try to stop the wheels. This would increase
> > the amount of current drawn by the motor, causing a heat build-up, and
> > potential damage to the plastic components holding the motor. This
> > would be a Bad Thing. So, the ploymer device, now being asked to pass
> > more current than it is rated for, begins to heat as well, causing the
> > current-passing element to become highly resistive, thus preventing the
> > motor from heating too much. This would cause the train motor to stop
> > working if it got too hot (maybe after pulling a really heavy load).
> > There are also thermal switches, versus this high-resistance device.
> >
> > So, if LEGO uses this technology in the motors, would they also use
> > them in the speed controllers? This could explain some of the problems
> > where folks put 2-3 motors on a train, and the controller finally
> > quits after a while, but then resumes operation after the device has
> > had time to cool.
> >
> > (I'm an ex-hardware-hacker, who hasn't opened his speed controller
> > or a LEGO motor (yet). I'm only offering one possibility. :-)
> >
> > -Z- http://baylug.org/zonker
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Message is in Reply To:
 | | Re: Train Depot DCC Update
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| Hmmm, that's a jolly fine theory, I didn't know such a material existed. Maybe I need to go back and figure out a way to incorporate the disc into the modified motor[1]. It would be kind of embarassing if my motor fell out onto the track one day (...) (28 years ago, 15-Mar-99, to lugnet.trains)
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