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In lugnet.trains, Martin Legault wrote:
> In lugnet.trains, David Laswell wrote:
> > Our club lets kids run the controller for one of the lines when we do certain
> > events (like, right now, with Detroit Festival of Trees), but we could use a way
> > to forcibly limit the speed on the line that they're allowed to run. One way
> > that's really easy is to just build physical stops onto the top of the regulator
> > so the dial won't turn as far in either direction, but that makes it difficult
> > to actually operate the dial and won't be much fun for the kids. The other
> > solution I just came up with would be to maybe limit the voltage going into the
> > regulator. And that's where there's a problem. LEGO power adapters, for some
> > odd reason, output in ~9vAC, not DC. ...
> Hello,
>
> you can put AC or DC voltage at the input of the regulator with no problem as
> long as you don't put more than 9VAC~14VDC. The internal circuit will take
> both.
>
> So a quick fix that put 4.5~5V DC at the input will ouput about 3~3.2VDC at the
> output.
You have to be careful here. The controller is designed to take AC or DC, but
the input diodes that that convert the AC to DC are only rated for 1 Amp (1000
milliampres). Make sure your transformer/wallwart is not rated for more than
this. That's more than enough for a train motor or 2. Also the interal circuit
including the diodes will drop ~2v no matter what. I'd use a 9v transformer,
thus giving you a maximum of 7v for that last 3 notches on the controller.
Which shouldn't be to fast.
Mat
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Message is in Reply To:
 | | Re: Reducing voltage
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| (...) Hello, you can put AC or DC voltage at the input of the regulator with no problem as long as you don't put more than 9VAC~14VDC. The internal circuit will take both. So a quick fix that put 4.5~5V DC at the input will ouput about 3~3.2VDC at (...) (17 years ago, 23-Nov-09, to lugnet.trains, lugnet.robotics)
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