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PV
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 Posted: Tue Nov 11, 2008 2:23 am Post subject: Re: DC voltage for conventional HO trains |
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a_a_a <a@a.a.net> writes:
| Quote: | Have you ever heard of that actually happening, or is this another of
those theory-rather-than-practice things?
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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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PV
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| Posted: Tue Nov 11, 2008 2:28 am Post subject: Re: DC voltage for conventional HO trains |
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cad@gamewood.net writes:
| Quote: | 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.
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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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Bob May
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| Posted: Wed Nov 12, 2008 5:16 am Post subject: Re: DC voltage for conventional HO trains |
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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
<autobus_prime@yahoo.com> wrote in message
news:7ffa7dcd-8e5d-45bc-8098-45a465c0fc3b@r37g2000prr.googlegroups.com...
| Quote: |
"Where there is smoke, there is fire."
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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