Date:         Wed, 12 Oct 94 17:13:22 EDT
Sender:       Vanagon Mailing List <vanagon@vanagon.com>
From:         dcarment@ccs.carleton.ca (David Carment)
Subject:      Re: cyl head temp gauge

H Steven Dolan writes:
> 
> Cylinder head temperature guages (and most other high temperature measuring 
> devices) use thermocouples as sending units.  A thermocouple is a 
> junction between two dissimilar metals.  When this junction is heated, 
> electrons pass from one metal to the other. Moving electrons = electric 
> current.  The greater the heat, the greater the current.  If you hook a 
> milliamneter to the output wires and calibrate it in degrees, you get a 
> temperature guage, with no outside current input.  As the current is 
> teeny even at high temperatures, the resistance of the lead wires must be 
> included in the calibration.  If you add to or subtract from the wires, 
> you will change the resistance, and thus the temperature reading.  And 
> now, back to our program....
> 
> 					H Steven Dolan
> 					dworkin@netcom.com
> 
I apologise for my stupidity but would the additional length of wire
running from the leads at the back to the gauge at the front need to be
included in this calibration? This would be almost impossible to do
accurately given the extra 8 feet of wire for each lead. DC> 


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David Carment
School of International Affairs
Carleton University
Ottawa, Ontario
K1S 5B6
voice - (613) 788-2600-6662
fax - (613) 788-2889
Email address: dcarment@ccs.carleton.ca
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