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 Robotics / 362
    Solar-powered RCX? —Brian Stormont
   Hi, How does the RCX handle things when there are batteries installed and it is also plugged in via the power jack? Does it use the external power first? I was curious if it would be possible to make a solar panel to power the RCX when there is (...) (26 years ago, 9-Nov-98, to lugnet.robotics)
   
        Re: Solar-powered RCX? —Kekoa Proudfoot
     (...) No, there is no way to tell as far as I know. I believe the choice of power source is done by circuitry, not logic. I do believe that the external power supply is used in preference to the batteries, but this might not really be the case - you (...) (26 years ago, 9-Nov-98, to lugnet.robotics)
    
         Re: Solar-powered RCX? —Michael Gasperi
     I think the RCX will use which ever supply voltage is greater. I havn't tested this, but I'll bet that when you plug the AC adapter into the RCX when the AC adapter is not even plugged into the wall the RCX will still work. This means there isn't a (...) (26 years ago, 9-Nov-98, to lugnet.robotics)
    
         Re: Solar-powered RCX? —Kekoa Proudfoot
     (...) I'm almost positive that the RCX uses whichever is greater, within a diode drop somewhere. But even still, I imagine that there is some leakage current from the batteries. Or maybe I was imagining that, and my batteries did not really drain. (...) (26 years ago, 9-Nov-98, to lugnet.robotics)
   
        Re: Solar-powered RCX? —Tom Boles
   Along the same line, does anyone have the specs on the co-ax power plug itself? diameter (outside & inside) and the polarity? I dont want to fry my brick through experimentation... Thanks, Tom (determining if there is circuitry involved should have (...) (26 years ago, 10-Nov-98, to lugnet.robotics)
   
        Re: Solar-powered RCX? —Kekoa Proudfoot
   (...) A plug that fits, with either polarity, 9-12V, ought to work fine. Capacitors and a rectifier do the conversion for you. Be careful, but don't worry about it too much. (...) As far as I know, it's not this simple. There is no mechanical (...) (26 years ago, 10-Nov-98, to lugnet.robotics)
   
        Re: Solar-powered RCX? —Tom Boles
   Sorry, maybe there is to much engineer in me but are you saying the external power supply produces low voltage AC and that it is rectified in the brick to DC to run the system? I can believe it's regulated inside, but it needs DC from the "wall (...) (26 years ago, 10-Nov-98, to lugnet.robotics)
   
        Re: Solar-powered RCX? —Ralph Hempel
     Tom Boles wrote in message <36486EB4.3941EC00@i...ns.com>... (...) Many embedded systems use a bridge to be polarity and AC/DC insensitive on the power inputs. At the very least, you should put a series diode to protect against reverse voltage. By (...) (26 years ago, 10-Nov-98, to lugnet.robotics)
    
         Re: Solar-powered RCX? —Chris Moseley
     Ralph Hempel <rhempel@bmts.com> wrote (...) Someone should tell Sony this - a friend fried my discman by reversing polarity. I had (foolishly) assumed that they would have dne this on the 9V external PS feed. Doh. Moz (26 years ago, 12-Nov-98, to lugnet.robotics)
   
        Re: Solar-powered RCX? —Kekoa Proudfoot
   (...) I believe AC is okay, although most wall warts are DC. Look at the little 9-12 V ~ symbol right near the port :) -Kekoa (26 years ago, 10-Nov-98, to lugnet.robotics)
   
        Re: Solar-powered RCX? —Ralph Hempel
   Kekoa Proudfoot wrote in message <199811101742.JAA037...rd.EDU>... (...) This implies a 9-12V AC adapter. This is a cost reduction, since a DC adapter is generally a transformer, bridge and minimal filtering. The Brick needs reverse voltage (...) (26 years ago, 10-Nov-98, to lugnet.robotics)
   
        Re: Solar-powered RCX? —Michael Gasperi
   I use a big transformer only type wall wart I had laying around. Pure AC output. The wall wart says it is 9VAC @ 3.2A but no load is about 10.5VAC. I'm sure this is more power than I need but it was free. If I look at the normally (battery) 8.2vDC (...) (26 years ago, 10-Nov-98, to lugnet.robotics)
 

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