Subject:
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Re: Help with converting voltage on circuit board
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Newsgroups:
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lugnet.robotics, lugnet.technic
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Date:
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Sat, 8 Apr 2006 11:34:20 GMT
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Viewed:
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2851 times
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In lugnet.robotics, Dustin Jones wrote:
> I've taken some more detailed pictures of the circuit and the reverse side.
>
> http://homepage.mac.com/dustinmj/PhotoAlbum16.html
>
> Reading through the manual, connections 6 and 7 are for sensors and connections
> 0-5 are for output (4V as labled on the cover), but you only can turn the
> circuit on or off. Connections A,B,C use the pairs of 0-1,2-3, and 4-5 to
> provide on, off and direction. The input from the wall transformer provides
> 13.8V AC 1.25 amps.
>
> Dustin
Thanks Dustin, those will help. I am inclined to agree with Philippe Hurbaine on
the regulator. It is also obvious that it can take AC from the full wave
rectifier near the power port.
In answer to Davids question about the 4v connector (using the old Lego
electrical connector), it looks more likely to be just a straight 4v supply
output, which is not controlled. Were it an input, the devices that are
compatible are pitiful battery boxes which would probably not handle the load of
more than one motor very well. Equally, I do not remember needing an input
voltage there when using it at school, although that was about 12-15 years ago.
However, since the supply goes there, before going to any of the H-bridge
transistors (the geometry of the tracks looks fairly straight forward on that),
then maybe you could cut the tracks coming from the main supply to there, or at
least keep a common ground, and put in 12v supply that would handle the load.
However, I still repeat my concern about the power transistors in the bridges
handling that larger voltage.
For anyone else who remembers this box, did it actually do any form of PWM, or
would you have had to do that yourself in the software? I do see potential timed
circuits, but maybe one would expect a 555 or equivalent.
Danny
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