From: "Barton B. Anderson"
Date: Wed, 15 May 2002 00:00:13 +0000
Subject: Re: [TSSP] Racing arcs
Hi Paul, All, Today I had an incident to the coil. Just prior to testing, my son wanted me to fire the coil up for a friend. I had something odd occur. No sparks off the top load and a tingy sound at each break. Sparks at the bottom of the secondary (very small). After checking misc., I fired it up again with same results. I then thought about the toroid connection. I remembered (mounting, remounting, etc.) the toroid was the last thing I did the day before. I checked the connection and it was loose and the 1 foot of wire was tucked down inside secondary instead of my normal mode of up on inside of toroid. Tried again and got sparks off the top - at the same time I noticed a spark at the bottom winding. Upon inspection, a 1/8" hole was in the winding (only maybe 4 or 5 turns from the bottom which is no big deal on an 1817 turn coil). Anyway, I began removing turns and there was a carbon track behind the winding on the former. I took approximately 5/8" off of the bottom. After a good cleaning, it fired up just fine, no racing arcs, and actually appeared to run better than previous (left tapped at 14 turns). Specs have changed (unfortunately): I decided to go ahead and make some measurements both electrical and physical: So here 'tis, Secondary: 8.4375" x 39.75". 1789 turns. Base height is 28.75" (note, coupling is now reduced to approx. 0.1307 due to bottom turns removed essentially moving windings up). Top height and toroid height remains unchanged from previous. Measured Ls = 131.1mH. R = 99.8 ohms. Measured sec bare in place (in garage): 113 kHz Measured sec toroided (in garage): 72.7kHz Well that's it. Sorry Paul, this kind of screws things up. Your probably fatigued from all these numbers this week and may not want to take more on. But, thought I should send this data to you anyway. No harm done to the coil. It couldn't have occurred in a better spot. Also, while unwinding turns, I noticed the position of the bottom winding had been positioned down as it should, but it came down about 75% of the first turn (typically, I run it down right at the beginning of the primary which is at the same potential). Take care, Bart
Maintainer Paul Nicholson, paul@abelian.demon.co.uk.