# Gauge Light Dimmer



## Yoyizit (Jul 11, 2008)

navman28 said:


> I installed a 25 ohm 3 watt rheostat to adjust my gauge lighting. When on, the rheostat gets extremely hot.


For 25 ohms to dissipate >3w you'd need sqrt (3x25) = >9v across it.

How much current do your gauge lights draw when full on? If they are incandescent lamps the calc. for a dimmer resistor gets really tricky. Does the 25 ohms make them dim enough?


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## navman28 (Oct 29, 2009)

I know the gauges are LED but dont know what they draw. Yes they do dim, just the rheostat gets really hot.


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## Yoyizit (Jul 11, 2008)

LEDs should be easy to control, but you need to measure the current draw at full brightness.
I^2 = 3w/25 ohms so I is at least 0.8 A. That seems high for LEDs.


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