Perry Mick wrote:

Paul:

I took some measurements on a leading coil yesterday.
Primary resistance is 2.5 ohms, inductance 4.05 mH,
secondary inductance 67.1H.  This gives a turns
ratio of 129.  With 2.5 ohms in the coil and .33ohms
in the resistor, if you just hooked up 14VDC to the coil/
resistor and let it cook, the resistor would dissipate
8.44W.

My guess is what is really making the resistors fail
is maybe a dissipation approaching the power rating
of the resistor, combined with heat, a hot ambient
environment.  In fact, the power rating of a resistor
decreases with higher temperature.

--
Perry J. Mick
Duckt N7XR
http://www.ductedfan.com

Most of the meters knocking around these days are pretty inaccurate at the
low end.  Mazda specs the leading coil primary at .5 ohm.

Tracy Crook
tcrook@rotaryaviation.com
www.rotaryaviation.com

 
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