Subject:
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Re: Does anyone know how to modify a train controler?
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Newsgroups:
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lugnet.trains
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Date:
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Mon, 22 Oct 2001 20:53:06 GMT
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Viewed:
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716 times
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Dean Husby wrote:
> Rick Clark wrote:
> >
> > I've also used this solution for some switching setups, and found it quite
> > useful. I can answer some questions, but the cost is that I'll ask a new one.
> >
> > No explosions, the motors work fine at 12v. I've even taken one up to 14v with
> > no ill effects, but I'm sure that continued usage would severely shorten the
> > life of the motor. And yes, the 12v setting will power the 12v light bricks
> > (as will the 9v), but in either case, you gotta find a way to make the
> > connectors compatible. The easiest way, I think, is to get a 12v wire, unscrew
> > the connectors, and separate them from the wire. Then take a 9v wire, cut it
> > in half, strip and tin the ends, and screw them into the 12v connectors. Now
> > you have two 9v to 12v connectors. Seems to work great!
> >
> > So here's my question: When I set the switch on the multi-voltage unit to
> > 7.5v, the LEGO speed regulator seems to only have about 3 speed settings, the
> > fastest of which is about half speed, and the slowest of which isn't really
> > even strong enough to overcome friction in the motor. So, electronics experts,
> > how come 7.5v doesn't give me 9 gradients of speed that are ~20% slower than
> > 9v (7.5 ~=~ 80% of 9) ?
>
> I think you've missed the point slightly.
>
> We are talking about 9 volt controllers and power supplies to the unit.
> The STANDARD power supply for the 9 volt controllers is 12 VOLTS AC! It
> turns it into DC 9 VOLTS inside the unit.
>
> When your using the less then 12 volts mode you're STILL taking the 3
> volt hit inside and the end result is a lowered total output.
>
> In your example, 7.5 volts is aprox 5 volts. That's not much for the
> train. It could degrade even more at low voltages. I'm not sure. I
> haven't had a chance to try it yet.
>
> Dean
You're right, I didn't understand the specifics, and this is why I'm not an
electrical engineer. So, to summarize, the wall wart that plugs into the wall
reduces 120v of AC electricity from the wall to 12v AC. Then, the train controller
receives the 12v AC as input, and converts it into 9v DC, which the train motor
uses.
So to Andreas's point, if you set a variable voltage transformer to 12v, it will
not only NOT blow up the motor, but it will make the train function exactly the
same as if you had plugged in the original, stock transformer, which is to say, it
will offer 9 gradients, up to a maximum of 9v. 12v in, 9v out.
So: 9v in, top speed will be ~75% full (9 / 12=.75)
7.5v in, top speed will be ~62% of full. (7.5 / 12 = .62)
etc.
For the record, though, at a recent train show, we actually did use a model
railroading transformer, which was able to direct 14v DC into the tracks, and we
ran a motor for several minutes, with no long term effects. It went really fast,
though!
Rick C.
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Message is in Reply To:
 | | Re: Does anyone know how to modify a train controler?
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| (...) I think you've missed the point slightly. We are talking about 9 volt controllers and power supplies to the unit. The STANDARD power supply for the 9 volt controllers is 12 VOLTS AC! It turns it into DC 9 VOLTS inside the unit. When your using (...) (23 years ago, 22-Oct-01, to lugnet.trains)
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