DC voltage for conventional HO trains


Folks:
Not necessarily. There may be pyrolysis, or vaporizing lubricant. I think it would be awfully tough to start an actual fire with a small-scale model loco. You might get high temperature, but the amount of heat would be quite low.
Lionel smoke units don't use fire. They just vaporize oil.
Model locos work fine with really basic control. I built a throttle a little while back with a TIP120, a 5k pot, a few resistors, and the transformer and rectifier from an old MRC Ampack, and it worked beautifully. My Railpower 1300 seems to be the same design.
Some use an automobile bulb for current limiting. Hook it up in series with the load.
12v nominal has been standard for a while. Of course, a pack needs to develop more than that on no load. There will always be voltage drop. Then you have MTH and their absurd ways. The less said about that the better.
Cordially yours: Autobus Prime w/minicon Farebox.
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The use of a light bulb in series with the tracks is always a nice idea when dealing with high power powerr supplies. You want to use a bulb that won't glaow when a normal load is present but when there is an overload, the light goes on. If you need more power, you can always put several bulbs in parallels to allow for the necessary running current. It sure lets you know when you have a short or other such problems with the layout.
-- Bob May
rmay at nethere.com http: slash /nav.to slash bobmay http: slash /bobmay dot astronomy.net

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a_a_a wrote:

It's one of those things you can prove to yourself quite easily.
Take a loco, sans superstructure, (so that you have access to the motor & gear train. Place on track, apply power, (the loco should move), Now grasp the motor shaft and squeeze, stopping the rotation of the motor. Now, turn up the speed control (while still holding the motor shaft to prevent rotation. SHORTLY, you will see 'magic smoke', and/or let go of the motor shaft because of heat from the motor.
Now, stop being so dis-believing of free information!!!
Chuck D.
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Charles Davis wrote:

Exactly. That is not a "small fire".

You are actually proving my point.
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a_a_a wrote:

What point? That you think that you qualify as a 'Nit Picker' ?
Chuck D.
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On 11/8/2008 6:27 PM Charles Davis spake thus:

Butbutbut ... that's exactly the sort of information one should be most suspicious of.
--
Washing one's hands of the conflict between the powerful and the
powerless means to side with the powerful, not to be neutral.
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Just remember Rule of Acquisition* #59: Free advice is seldom cheap.
*The Rules of Acquisition are a Star Trek DS9 invention. They're the rules that govern the businessman-race called Ferengi.
Puckdropper
--
If you're quiet, your teeth never touch your ankles.

To email me directly, send a message to puckdropper (at) fastmail.fm
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Puckdropper wrote:

* The Rules of Acquisition, though a completely fictional creation, are none the less useful for stating in rather succinct and obvious truthfulness, what would otherwise be referred to as 'Common Sense'.
Chuck D.
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David Nebenzahl wrote:

Correct ---- but with a little 'Common Sense' thrown into the mix.
If something glaringly wrong is stated, there WILL be other comments to that effect.
[Actually the 'Free Information' is mislabeling what shows up here. (R.M.R)]
Chuck D.
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snipped-for-privacy@gamewood.net writes:

Not really. While I have had decoders destroy themselves to protect the motor (sigh), I've also had several that simply turned themselves off - it's not like a stalled engine is a super-rare situation. Actual melting is going to be a lot more common on a DC layout. *
--
* PV something like badgers--something like lizards--and something
like corkscrews.
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This happened long before I joined the group, but a local Ntrak club tells stories about one locomotive that started smoking. Remember the old axiom, where there's smoke, there's fire.
I doubt a small fire would be started in seconds rather than minutes. It would seem to me that the heat required for combustion around mostly metal and carbon would be much greater than what could be generated at 60W (Assuming a worse case scenario of 12V at 5A.)
Puckdropper
--
If you're quiet, your teeth never touch your ankles.

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a_a_a wrote:

Yes, I saw smoke drifting from under a loco about 20 years ago. I was using a homebuilt 5-amp DC power supply. Naturally, it was fused for 5 amps. There was no permanent damage. But it's one of the reasons I recommend small powerpacks. OTOH, I have burned out small train-set powerpacks, when they tried to deliver the 1.5-2 amps that old open frame motors demanded under heavy load (and without overheating.)
Sparks, smoke, etc happened (and still happen) frequently with Lionel, when those very large transformers are used.
I had am Atlas N scale loco start smoking a year or so ago. It stalled at a turnout. I think it was miswired, as it was the PC board that burned up. Anyhow. Atlas replaced it without comment.
I'm sure others have similar, um, interesting tales. ;-)
--
Wolf Kirchmeir

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Not a BIG fire mind you, but yes, I have seen a train motor catch fire. And I've seen others get hot enough to melt plastic but not actually ignite.
In both cases these were very old open frame motors - I think modern electric motors deal with stalling a lot more gracefully. *
--
* PV something like badgers--something like lizards--and something
like corkscrews.
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