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 18:41:02 GMT
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Viewed:
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618 times
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> Ralph Hempel <rhempel@bmts.com> wrote in message
> news:000001bf0901$f58c67a0$0500000a@pro150...
> > > I'm in over my head with a project and need some help. I'm
> > > trying to use an RCX
> > > output port to control a 5VDC SPDT Relay from Radio Shack (part
> > > #275-240A).
>
> I would just put a 33Ohm 1/2W resistor in series with the relay coil.
> According to the spec for the relay, the coil wants 5V at 90ma. The RCX
> outputs about 8V with full power so that is 3V too much. The
> resistor must
> eat up the 3V at 90ma. V/I=R so 3/.09=33 ohms. I^2 R=Power so (.09)^2
> 33=.27W so use a 1/2W. = RS#271-1104.
Leave it to Michael to actually go through the math and put the right
answer up for the group to see - nice work.
Cheers,
Ralph Hempel - P.Eng
------------------------------------------------------
Outside of a dog, a book is a man's best friend.
Indside of a dog, it's too dark to read...
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Reply to: rhempel at bmts dot com
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Message is in Reply To:
 | | Re: 5VDC Voltage Regulation
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| Ralph Hempel <rhempel@bmts.com> wrote in message news:000001bf0901$f5...@pro150... (...) 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 (...) (25 years ago, 27-Sep-99, to lugnet.robotics)
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