Subject:
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RE: 5VDC Voltage Regulation
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Newsgroups:
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lugnet.robotics
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Date:
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Mon, 27 Sep 1999 19:19:21 GMT
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Viewed:
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633 times
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> > I would just put a 33Ohm 1/2W resistor in series with the relay coil.
> > According to the spec for the relay, the coil wants 5V at 90ma. The RCX
> > outputs about 8V with full power so that is 3V too much. The • resistor must
> > eat up the 3V at 90ma. V/I=R so 3/.09=33 ohms. I^2 R=Power so (.09)^2
> > 33=.27W so use a 1/2W. = RS#271-1104.
>
> This doesn't seem to work. I am trying this first since it is
> the simplest
> solution so far and I have a 330hm resistor at hand. Without the
> resistor the
> voltage across the coil with he port set to level 7 is 7.17.
> When I add the
> resistor in series the coil no longer functions and the voltage is 7.74.
Ummmm, I think Michael meant to say 33 Ohm resistor. That's what his
calculation says and like soooo many others, I just looked at
the answer without checking the math...
Cheers,
Ralph Hempel - P.Eng
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Outside of a dog, a book is a man's best friend.
Indside of a dog, it's too dark to read...
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Reply to: rhempel at bmts dot com
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Message is in Reply To:
 | | Re: 5VDC Voltage Regulation
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| (...) This doesn't seem to work. I am trying this first since it is the simplest solution so far and I have a 330hm resistor at hand. Without the resistor the voltage across the coil with he port set to level 7 is 7.17. When I add the resistor in (...) (25 years ago, 27-Sep-99, to lugnet.robotics)
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