Subject:
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Re: Eliminate high-speed derailments forever! (and possibly void your warranty)
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Newsgroups:
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lugnet.trains
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Date:
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Mon, 23 Aug 1999 18:37:40 GMT
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Viewed:
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667 times
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Actually, lowering the voltage would lower the current draw too with a
constant
load. Of course a motor is anything but a linear load, and it does tend
to draw more
current at slower rpm. In any case, you're not going to break it, since
the 9v
train controller is basically a big potentiometer, (or more likely a
rheostat), delivering
less voltage closer to the center detent.
KL
Tom McDonald wrote:
>
> In lugnet.trains, John R. Clark writes:
> <snipped interesting idea>
>
> > So the obvious question is: Am I damaging/shortening the life of my • transformer
> > by feeding 1.5 volts less than it expects into it?
>
> The transformer in the wall socket adapter probably won't be bothered too
> terribly, as it's only a 17% reduction in voltage. The motors don't try and
> suck additional current to make up for it. But a 17% raise in voltage however
> is *not* recommended, if anyone is thinking of trying it. You could overheat
> or fry it.
>
> > And another question that someone with more electronics knowledge than I have
> > can answer: The universal converter has removable male jacks, which are
> > designed
> > to fit many different devices. They are also reversible, which means that the
> > tip can be either positive or negative. So does it matter which way it goes
> > into
> > the transformer?
>
> In this question, by stating "transformer", I assume you mean speed
> controller, where it absolutely does matter by that point. The wall socket
> adapter itself has the rectification that converts AC into DC, and the step-
> down transformer which converts the higher voltage to 9V or 7.5V.
>
> It's okay for the speed controller to have approximate voltage to play with,
> such as 7.5V in this case, but the polarity must always match. Why would you
> need to switch polarity if the speed controller can make things go backwards?
>
> Older adjustable voltage regulators (such as the LM317) require correct
> polarity to function, and there could a couple in there or their equivalents.
> Incorrect polarity could well do damage, but at the very least I expect the
> LED not to work.
>
> -Tom McD.
> when replying, all natural spamcake contains no triglycerides!*
> *spamcake has been known to cause tumors in laboratory technicians.
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