Subject:
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Re: DCC for the RCX
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Newsgroups:
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lugnet.trains
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Date:
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Fri, 30 May 2003 04:33:17 GMT
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Viewed:
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2742 times
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Huh??!? Your basic resistor can only handle 1/4 watt (0.25W), so your
worst-case 2.8W is more than ten times the rated maximum current. Even
dumping an “insignificant” 0.5W across a resistor is probably not adviseable
unless you are also trying to heat your house. With fire. And don’t forget
that all of this power is being supplied by the motor driver circuit of your
precious RCX which has limits of its own.
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I don’t know about you, but I tend towards .5W or bigger for most of my
resistors, and diodes have exactly the same problem if you use them as a voltage
drop. Load is not really signifigant on a 5A booster (soon to be 10 amps
total...2 boosters). You would save 0% of your loss by using diodes vice using
resistors:
E=RI regardless of anything else, and w=IE, so to get your 5V drop at 100 ma
draw, you are loosing .5W regardless of if you use a diode, a resistor or a 2nd
light.
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Is it worth trying to save a few pennies using a resistor to do a diode’s job
at the risk of doing dammage to your RCX?
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Yes, since it doesn’t make any difference whatsoever as to how the job is done.
None. Not at all. So, use the cheaper resistor if you are dropping the
voltage. Another thing to think about is that you only need 1 set of diodes if
you are going to do this, since the acc leads are DC off a DCC decoder.
James
(and if all else fails, show me your converted motors!)
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Message is in Reply To:
 | | Re: DCC for the RCX
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| (...) Huh??!? Your basic resistor can only handle 1/4 watt (0.25W), so your worst-case 2.8W is more than ten times the rated maximum current. Even dumping an "insignificant" 0.5W across a resistor is probably not adviseable unless you are also (...) (21 years ago, 29-May-03, to lugnet.trains, FTX)
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