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Re: GM coil record

Hi Jim,

A few "hints" are at:

http://users.better.org/tfritz/site/misc/GMHEI.ZIP

This zip file also has the "top secret" schematic with values in it!

Use sharp tungsten points for the gap.  I used nails and they burnt quickly.

I also used a needle point on the top terminal and a lightning rod for a
ground to jump the spark.

It is also interesting to note the use of an array of 630V polypropylene
caps operated far above their specs for the primary capacitor.  :-)

Bob's data does not apply much.  With the core removed, saturation problems
of the steel core are eliminated and it is a true Tesla coil.  The 1600V
1.7uF cap has more than 100mJ ;-O)  The above data and the details in the post

http://www.pupman.com/listarchives/2000/January/msg00257.html

and should provide all the info needed.

For those that "don't get it"...  Long ago I started a project to make a
simple easy to build "beginner's" Tesla coil out of a General Motors HEI
ignition coil.  I was successful!  Unfortunately too successful...  The
coil's high energy and low frequency of operation make it very dangerous!
Definitely NOT a beginner's toy!  The 10kHz 92,537 volt output will hit you
like a ton of bricks if you were ever to connect with it.  However, the old
typical spark lengths of 6 inches for auto ignition coils operated in the
ludicrous region were far exceeded (I do modify it by removing the steel
core).  As far as I know, the 13.25 inch arc I got out of an ignition coil
is by far the furthest ever recorded.  In this case, the General Motor's
coil was picked as a standard.  Ford and others coils don't count toward
the "GMHEICSLR".

Cheers,

       Terry
        Still proud holder the coveted GMHEICSLR* at 13.25 inches. :-))

*General Motors High Energy Ignition Coil Spark Length Record

BTW - Unlike other similar, but less important, things like the Stanley Cup
or the America's Cup, the GMHEICSLR has no cup.  I'll try to remedy that
situation this weekend! ;-))


At 09:39 AM 04/20/2000 -0700, Jim Lux wrote:

snip...
>
>Rules of engagement are important...   Is that the SGMHEICSLR? (SINGLE
>GM....) or are you claiming a record for any number of HEI coils.
>
>I am too lazy to look in the archives, but was that almost 14" spark with a
>cored or de-cored HEI coil?  I know you were driving it at somewhat above
>its design primary voltage (heh,heh)...
>
>based on some numbers that Bob Wroblewski sent me, at 12Volts, the limiting
>current will be about 3.2 Amps (DC resistance is 3.7 ohms by working from Q
>measurement).  With the 3.6 mH inductance, this is a stored energy of a
>feeble 10-20 mJoule, which seems low ( I'd expect 50-100 mJ, stock).  As I
>recall, you were pumping a joule or so?
>
>