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  #41  
Old 9th February 2010, 09:55 PM
Enoch Enoch is offline
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You have that the wrong way round Baz - the resistance of the bulb is the constant, it's the voltage that's the variable. As voltage increases and the resistance stays the same the current increases. Therefore higher engine speeds = higher voltage = higher current. always allow for this in calculating wire ratings. In the aircraft industry we used to do that, add 50 per cent then double it
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  #42  
Old 9th February 2010, 10:10 PM
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alga alga is offline
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Well, that's close to multiplying by pi, which is used when estimating software development ;-D
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Haynes Roadster FAQ | Haynes Builder Locations
Gallery, build thread in Lithuanian / via Google Translate.
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  #43  
Old 9th February 2010, 10:48 PM
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AshG AshG is offline
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i worked out the rating then doubled it on everything.
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  #44  
Old 11th February 2010, 05:56 PM
baz-r baz-r is offline
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Quote:
Originally Posted by Enoch View Post
You have that the wrong way round Baz - the resistance of the bulb is the constant, it's the voltage that's the variable
doh i know. i was just thinking in the wrong wavelength again
its the night shifts you know
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  #45  
Old 11th February 2010, 06:18 PM
baz-r baz-r is offline
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here's a quick calc linkey so no thinking is required

http://www.sengpielaudio.com/calculator-ohm.htm

55w bulb = 2.61 ohm at 12v

11.5v=4.41A
12v=4.58A
14v=5.34A

Last edited by baz-r : 11th February 2010 at 06:19 PM. Reason: typo
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