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Re: Re: Re: Dew Removers

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Posted by Rick Crockett on December 18, 2000 19:20:43 UTC

Hi Walt:

680 ohm resistors are a common size and available at Radio Shack etc. It is the smallest common size that will allow you to drop 12VDC safely with a common 1/4 watt resistor. Using a smaller size carbon resistor, risks the possibility of thermal runaway in which the resistor catches fire and explodes. This was a common lab demonstration I saw many times as a student lab tech. That is why I sized the 1/4 watts at 680 ohms in my web page dewheater article. 1/2 watt resistors are harder to come by.

Good Luck,
-Rick

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