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In lugnet.technic, Larry Pieniazek writes:
> In lugnet.technic, Trevyn Watson writes:
> > I think you misuderstood what Larry said (or I misunderstood what you
> > said). I think Larry was saying that you should use the wall wart from
> > the train speed regulator, which is what Lego recommends.
>
> Yes. That is what I meant. I even believe sincerely that it's what I said. :-)
>
> I am not sure who exactly within LEGO first recommended it but if you dig
> hard enough in lugnet.robotics I believe you will find just such a
> recommendation.... that you should use the wall wart from the speed reg (not
> the speed reg itself) to power your RCX if you so desired.
>
> If you put DC through a bridge you get 100% duty on one side and 0% duty on
> the other, possibly resulting in asymmetric heating, contrast with AC which
> gives 50-50 duty. Maybe that's what ROSCO was referring to.
>
> However I would like to point out that the wall wart in my hand (from a 4558
> I have handy) (which is stamped "Made In China for the LEGO Group", (sans
> any (r) symbol, shame on them, but I digress)) takes in 120V AC & .12 A and
> puts out 11 Volts AC & 7VA.
>
> Do wall warts issued for 220 regions put out DC instead? If so that would
> tend to be just as likely to burn out the bridge rectifier in the speed
> controller if it is expecting AC, would it not? It may be a bit more rugged
> than the one in the RCX though.
>
> (and in fact hearsay at the time of the 1.5 introduction was that this was
> precisely why it was omitted, that they had too many field returns of the
> 1.0 RCX with burned out bridge rectifiers... not that it was a cost savings
> in manufacturing driven change)
I'd be a little surprised at a bridge rectifier which couldn't accept DC. Many
electronic appliances have them these days so that it doesn't really matter
what kind of wall wart you use, so long as the voltage is in the right range.
The wall wart can supply AC or DC, and it doesn't matter what the polarity of
the DC is.
Frank
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Message has 1 Reply:
 | | Re: Powering motors from the mains
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| (...) The main problem comes from the heat generated. This isn't a problem, unless you're driving motors fairly constantly with your RCX, but can eventually cause the diodes to break down. Of course, when one half of the rectifier goes, you can (...) (22 years ago, 19-May-02, to lugnet.technic, lugnet.robotics)
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Message is in Reply To:
| | Re: Powering motors from the mains
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| (...) Yes. That is what I meant. I even believe sincerely that it's what I said. :-) I am not sure who exactly within LEGO first recommended it but if you dig hard enough in lugnet.robotics I believe you will find just such a recommendation.... that (...) (22 years ago, 18-May-02, to lugnet.technic, lugnet.robotics)
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