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Subject: 
Re: Powering motors from the mains
Newsgroups: 
lugnet.technic, lugnet.robotics
Date: 
Sat, 18 May 2002 04:19:13 GMT
Viewed: 
258 times
  
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)

++Lar



Message has 3 Replies:
  Re: Powering motors from the mains
 
(...) 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 (...) (23 years ago, 18-May-02, to lugnet.technic, lugnet.robotics)
  Re: Powering motors from the mains
 
The current is going through two silicon diodes though, with attendant .5 volt drop through each so consider if that will be a problem in this application. Likely its not. (...) Tom Napolitano tomnap@bersama.net (23 years ago, 18-May-02, to lugnet.technic, lugnet.robotics)
  Re: Powering motors from the mains
 
(...) Ooops! Silly me! Yes, the Australian (240v) train reg adapter is also 10v AC, so fine to use with RCX. ROSCO (23 years ago, 19-May-02, to lugnet.technic, lugnet.robotics)

Message is in Reply To:
  Re: Powering motors from the mains
 
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. Also, I dont see how you could burn out the diodes (...) (23 years ago, 18-May-02, to lugnet.technic, lugnet.robotics)

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