Ohms Law ???
Thread Starter
Race Director
Joined: May 2006
Posts: 16,528
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From: Dayton, Ohio
It might look like I removed some but its just the differences from one resistor to another , still read around 86 ohms.
The customer that gave me all the books just loaned me an Omega thermocouple so I can get some accurate temp checks.
Le Mans Master
Joined: Oct 2000
Posts: 8,897
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From: Santa Ana CA
So I built a new one today.
5 watt 68 ohm wire would resistor and a 100 ohm variable resistor.
Took a photo before I do the final shrink wrap.
Overall size 2cm's by 1.5 cm's.
Currently set at 90 ohm total.
Will mount it into the car on the weekend with the module attached to the heater box.
5 watt 68 ohm wire would resistor and a 100 ohm variable resistor.
Took a photo before I do the final shrink wrap.
Overall size 2cm's by 1.5 cm's.
Currently set at 90 ohm total.
Will mount it into the car on the weekend with the module attached to the heater box.
The needed watts for the resistor is not as great as you have been led to believe. In all prior calcs I noted, the power requirement is based on the car voltage and the resistor to be added to the circuit. But I fail to see where anyone has included the resistance of the actual sender unit (whatever that may be) in the power calculations. You need to look at the entire path.
If the power requirements are a high as you've been led to believe, your potentiometer (being used as a variable resistor) will be very short lived. While the resistor may have adequate wattage, that pot can't be rated for more than 0.5 watt or so. If the pot is turned to the same value as the wire wound resistor, they both see the same wattage. So its way overkill on the wirewound, or you'll be smokin' that pot.
Last edited by toddalin; Sep 10, 2010 at 09:03 PM.
