Re: Reducing voltage

"Matthew J. Chiles" <[email protected]> Mon, 23 Nov 2009 17:13:35 GMT
Newsgroups gmane.comp.hardware.lego.robotics
Organization None
Message-ID <[email protected]>
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.  Finding an AC-AC power adapter is
> difficult at best, and the only two that I can find through Radio Shack (the one
> place I knew of that _does_ sell them) run 9-13vAC or 18-24vAC, which is not
> going to help at all.  They do sell an adapter that goes as low as 3v, but it
> outputs in DC instead of AC, and I'm not having much luck doing a generic
> internet search for adapters that output in AC below 9v.  Does anyone know where
> I might be able to find such a beast?

Years ago PNLTC used to do this for the kids table at the show.  From what I
recall, we just drove a screw though the controller at about the 4th notch in
the black area on each side to keep it from turning too far.  It is a very long
lasting, inexpensive and easy solution.  Any old PNLTC guys out there remember
exactly how this was done?

If no one pipes up, I would unscrew a controller and see where the screw would
stop the dial without damaging any internal components

-Matt :)