Tesla Coil Help

[skyler]

For a club I started at my high school, everyone agreed on making a tesla coil as a project.

I am starting to struggle realizing how everything has to be tuned, resonant, and I can't just throw a random number of turns on a random size PVC pipe. We are limited in price, so I will say our progress so far of what we have and ask a few questions.

•A piece of 4 inch Diameter 5 foot PVC pipe (actually have 2 of those) and a toilet plounge to hold it up 90 degrees

•A bucket capacitor made out of salt water, beer bottles, oil, I will post the capacitance tomorrow when I bring my capacitance meter

• 4 MOTS, we might have to get another for the ballast, correct? We will be hooking two outlets together for the Power Supply

•A stable spark gap (planning on rotary probably in the future, I have a 3400 RPM BIGG motor that may work)


Our Price is very limited, for we have few sponsors, (just my friend and I's parents and our own money)

So what are some next steps, and is the PVC not the right size? (From another question on the forum the pipe seems to be not the right size, my dads gonna get mad that he wasted his money on that and probably wont buy another     

I am sort of confused when working with JavaTC so if anyone could help me with that, it would be great!

Safety wise, I Know 4 mots is enough to KILL YOU  so we are taking every safety precaution including being at least 10 feet away when any transformer is plugged in.

What should I use for Primary wire?

Thanks for ANY help, Im just a dumb high school student, and need a bit of help from people who know what they are doing

73's

[houdini]

Go look on 4hv.org there are way more experienced hv people over there.

[skyler]

I am now working on the rotary spark gap Phase.

I have a 3450 RPM Motor.

I was looking around for tungsten rods. http://tb3.com/tesla/sparkgaps/srsg_IX/srsg_I.html said to use 7inch 5/32 tungsten rods.

So I do a little search on google. Some results were 100 bucks, and I found a bit cheaper for 70 http://www.ebay.com/itm/5-32-X-7-Pure-Tungsten-Electrodes-6-Shipping-/130038070829

I am on a very low high-school budget and will pay no more than 30 bucks for all of the electrodes, due to having so much more on the list to buy for the tesla coil. Is there any alternative, or place to buy tungsten electrodes a bit cheaper?

[Andy Watson]

Does the tungsten have to be 5/32? It looks like you're paying a premium for using an odd-ball size. Would 1/8 do, or 3/16 TIG welding electrodes?

[skyler]

Does the tungsten have to be 5/32? It looks like you're paying a premium for using an odd-ball size. Would 1/8 do, or 3/16 TIG welding electrodes?

Wish I knew, just looking at some spark gap designs online

[ron]

Does the tungsten have to be 5/32? It looks like you're paying a premium for using an odd-ball size. Would 1/8 do, or 3/16 TIG welding electrodes?

Wish I knew, just looking at some spark gap designs online

Nothing magical about 5/32.  XX Years ago I restored a large TC that used common
40penny nails for electrodes.  It worked great.  After ~10-15 min the gap would grow out of range and the coil had to be shut off and the primary discharged for gap adjustment.  It was so loud that no one wanted to hear it for more than a few min. so not a problem.

[BThunderW]

it's been years since I built a Tesla coil, been itching for a while to build a solid state version. All my previous coils were based on 12kv/15kv NST's.

[skyler]

•I finally got the MOTS (microwave oven transformers) to work, by correctly wiring the secondary coils (using the core of two mots as the center, and removing the connection to the core on the outer MOTS, as well as submersing the entire power supply in oil) and have a HIGH current 8KV power supply.

•I have experimented with several ballasts, including a MOT with the secondary shorted, a big hunk of aluminum etc, and am close to finding a good setup with the amount of current I have available (20amps-30amps)

•I used a 3450 RPM pool pump motor for the rotary spark gap. (Yes, I know it isn't Synchronous, and blah blah but this youtube video has an awesome Quad mot coil using 3450. )
The motor is very similar to this setup, using tungsten rods. -->

•I have a primary coil of 100 feet copper wire wound, but it might be a bit uneven (like goes up and down a bit).

•I still have my 12-15nf home-brew bucket capacitor as well as the large secondary with 12ft diameter and 4 feet height.

THE PROBLEM

I got the spark gap to fire Perfectly, so next step, I hook up the Series string of primary coil and bucket cap in parallel with the spark gap, which was firing perfectly

But.... Nothing, the primary coil fails to fire until I disconnect the capacitor primary string, and then it fires again.

What is going on? Does it have to do with it not resonating and the cap having a wayy off value (which i know is true, I thought I could compensate by buying 100 feet of copper tubing)

Thanks for any help, we are out of ideas and would love any input!!! HD Pictures of setup will come as soon I can get to my friends house again (as he has the coil)