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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Mon, 15 Mar 1999 21:03:00 GMT
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Viewed:
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1069 times
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In lugnet.trains, Matthew Bates writes:
> 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.
Didn't open a motor yet but with the description I would say that it is a
thermistor (thermal resistive device). Better find a way to live it in place.
> > 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.
When I opened my controller I didn't saw (or remember seeing) such a device
inside it. Could also be that the voltage regulator overheat and there is a
thermal protection inside to protect. (Will have to reopen it again an check
the spec of the device.
Martin
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Message has 1 Reply:
 | | Re: Train Depot DCC Update
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| (...) I suppose I could try soldering wires to it and thereby put it between the DCC decoder output and the motor. Does it need to be thermally coupled to the motor though or is the heat of the current passing through it sufficient? Matt (25 years ago, 15-Mar-99, to lugnet.trains)
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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 (...) (25 years ago, 15-Mar-99, to lugnet.trains)
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