The Fabulous GMHEICSLR* WORLD CUP!!!
This cup was created as a challenge, by Terry Fritz, the moderator of the Tesla-Pupman list, on 1998 when he, during a research aimed at creating a beginner’s coil, found out that a GE coil could be made to spark over a foot far when driven in Tesla Coil mode (air core, spark gap, tank cap, etc). Below you will find information on the cup, and the setup I am preparing to win it with. Terry is getting a little cocky over his record, its about time someone beats him 😉
*General Motors High Energy Ignition Coil Spark Lenght Record
GMHEICSLR "Rules of Engagement"
1. The coil used must be a “GM” High Energy Ignition Coil. No other makes are accepted. It may however be modified in any way that does not significantly affect its principle of operation. It can also be obtained from any aftermarket manufacturer as long as it is a direct replacement for the OEM part.
2. Only one coil can be used at any given time. Of course, you can burn up 10s, 100s, or 1000s of coils in attempting to beat the present GMHEICSLR ;-))
3. It must be operated as a “Tesla coil”. Capacitive discharge or CW is fine, but records in which more input voltage was put in than was outputted (e.g. pumping the base with a larger Tesla Coil) are invalid.
4. The coil must operate at least twice at the given spark length.
5. Since this really IS the world’s record, any person my make the attempt weather they be on this list or not.
6. You must be willing to disclose any details of the setup you use to achieve the GMHEICSLR. This maintains competitiveness and insures verification. This should not be a problem because even when you know everything, is still is not at all easy!
7. It has been noted that this type of coil can be very dangerous, so be extremely careful and assume responsibility for any mishaps.
8. Other rules may be added if needed but we will NOT nit pick…
And here is the man himself, holding proud to his trophy… Well just you wait Terry 🙂 I am already making space for this on my shelf 😉
Here is how Terry did it (narrated by him on a post to the list last year):
1. Get a brand new GM ignition coil (76 Cadillac 500 cid engine) from the cheap auto parts store (~$15). Old ones out of cars will have cracks and flaws in the vacuum impregnated core which will fail in this ~200kV service.
2. Grind off the welds on the outer steel laminated care and discard it. Beware the very sharp edges.
3. Epoxy a 16 inch long 2 inch diameter PVC pipe over the high voltage button. Solder long wires to the primary connections and connect the secondary ground lead to a wire connected to a good earth ground. Position the coil in an oil bath with the tube pointing up.
4. Fill the tube with oil too so that the whole thing is in, and insulated by, oil. You will have to space the coil off the bottom of the container too so there is about an inch of oil there. There is a lot of HV in a small place so the oil is all that is keeping the thing together. I put it all in a big pan to collect the coil if something goes wrong.
5. Position a metal rod down the center of the tube and place some little ball or something on the top for a terminal.
6. The spark gap will have to fire at about 1000 – 1500 volts. I used two sharpened nails that points could be closely adjusted to about 1 mm (that is a millimeter ;-)). Tungsten would have been the material of choice.
7. I used 0.1 uF 630V poly caps (well over their rating, EMMC work was going on then too…) for the primary cap. I needed 1.7uF in the primary but your mileage may vary. I added or subtracted caps to adjust the value for the best spark.
8. I used a high voltage (rectified ignition coil) power source to slowly charge the primary cap up. The wider the gap the longer the sparks. Don’t go over one pulse per second or the coil will die too soon. 10 inch arcs at 1000 volts seemed pretty safe. 1500 volts at near a foot is getting close to the destruct point of the coil. I got 13.25 inches from one (single coil not two – that’s cheating ;-)) coil to a pointed ground rod before I blew my best setup. This all shows dramatically the advantages Tesla coils have over conventional transformers for making big sparks. You would be very lucky to get a 6 inch spark out of a GM coil using it as a transformer or induction coil. The steel core will saturate and et up all the power after a certain point. With the core removed, you have a True Tesla coil air core resonant circuit that can develop as much voltage as the epoxy in the coil will stand. I cut open and examined a number of coils I blup.ew. One was defective, one was cracked, but the 13.25 inch one was perfect. The present record is 13.25 inches which was achieved twice, before the coil blew, on November 22, 1998 by Terry Fritz. Here are some images of his setup.
How I intend to beat the record:
Making the coil output more voltage presents no challenge at all, all that is needed to do is input more V. However, it seems as though the epoxy enclosure will not stand more than perhaps 230KV before it arcs over internally. Therefore, I will construct a very high efficiency system utilizing a loss less vacuum gap, heavy primary conductors, silicone oil insulation, H.V. cabling, pulse capacitors matched to the transformer, so as to maximize energy transfer to the spark, and than (here is the differential), look for ways to maximize the directivity and minimize energy losses through that spark. I believe the secret to beating this record lies in a properly matched top load.
I have now obtained a GE HEI Coil!
Emery Wayman sent this coil to me new, in its box through Fed Ex shipping to me in Holland (!!!) A year ago when I was helping him with his Bonetti Electrostatic Machine THANKS EMERY!!!
Work starts next week. I shall begin by removing the core and building an enclosure for it and the 500ml of silicone oil I am obtaining.