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Subject: 
Re: Motors comparison page updated
Newsgroups: 
lugnet.robotics, lugnet.org.us.smart
Date: 
Thu, 13 Jan 2011 08:31:23 GMT
Viewed: 
136 times
  
Hi Brian,

Thank you! Surprising that with as easy as it is to backdrive, that the
efficiency is as low as it is.

I was surprised too. I suspect a relatively high internal resistance of the
windings, rather than mechanical friction, as the source of losses. No, (shame
on me!) I didn't checked yet with an ohmmeter.

Out of (not idle) curiosity, is it possible to drive even more current-hungry
devices safely from the NXT? I need a way to drive a 120V AC, 15 amp device
under NXT control (I need to be able to cycle it on/off rapidly with a variable
duty cycle, to control average power output).
This is clearly outside of my own SOA there
(http://en.wikipedia.org/wiki/Safe_operating_area)! Are you sure that duty cycle
modulation works with this kind of AC motor? You would need to synchronize with
mains... Or - to keep it simple and safe - you might try to control the dial of
a powerful light gradator with a NXT motor?

Philo



Message has 1 Reply:
  Re: Motors comparison page updated
 
(...) I've been operating outside my personal SOA for years now :) (...) It's actually not a motor - it's a small electric hot water heater element. When plugged in it produces 1300W, but if I want less than that I need to figure out some way to (...) (14 years ago, 13-Jan-11, to lugnet.robotics, lugnet.org.us.smart)

Message is in Reply To:
  Re: Motors comparison page updated
 
(...) Thank you! Surprising that with as easy as it is to backdrive, that the efficiency is as low as it is. Out of (not idle) curiosity, is it possible to drive even more current-hungry devices safely from the NXT? I need a way to drive a 120V AC, (...) (14 years ago, 12-Jan-11, to lugnet.technic, lugnet.robotics)

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