Tesla Coil Project - Need Help Please

[DerStrom8]

Your right anything is a certain range works fine for a secondary coil. I did a lot of experements with secondary coils 950 turns is a very good place to start it is very easy to match your caps to that number of turns. If you wind 2 or 3 coils over each other 950 turns each and connect them in parallel you lower the wire resistance and the secondary coil works better. If your trying to get the absolute max out of your system tiny little things help add an extra 1/2" or more to the output sparks.

I always wondered if that would work!

CPU fan works good on a low power coils but not enough cooling for a 12 KW coil. Nice thing about a VSFFSG = Variable Speed Vaccum Fan Spark Gap is you can turn the variac and watch your output sparks get longer and shorter as the fan picks up speed. As the fan picks up speed the output sparks get longer and longer up to a certain point where they reach maximum length. Now you have 1 more adjustment that you never had before that helps you turn your TC. Richer Hall once said, VSFFSG works better than a rotor spark gap and it is much easier to build and costs less too.

This coil is only 360 watts, so I think a CPU fan would probably be sufficient for now. However, if the OP has access to a vacuum cleaner fan and motor, or if he has a variac and an AC fan, that would be even better.

So Marco, whaddaya say?

Regards,
Matt

 

[marcopolo09190]

Woah thanks everyone who've replied to this thread so far and helped with all the input I can't thank you all enough, especially you Matt!

Now back to the Tesla Coil:

I don't really want to change the secondary coil winding's so I'm going to keep that the same.

For my version 1 Tesla Coil I'll just leave the spark gap without a fan but I will move the copper tubes further away from each other. I'm planning to build another Tesla Coil after this one to be more effective after this one works.

I'm planning to try tune the Primary Coil by moving the wire every few centimeters at a time. If this does not work, then I will go ahead and build a new Primary Coil.

Does anyone know any good effective designs for Primary Coils?

And thanks ()blivion, I think I will make that Chicken Stick

Thanks everyone and can't wait for any of your replies

P.S. gary350, the reason why I didn't buy any capacitors / buy designs is because of what Matt said with how its a student project so I don't want to spend too much money and I want it to be "My Own Design".

Thanks

 

[DerStrom8]

Does anyone know any good effective designs for Primary Coils?

The conical type is generally used to make coupling adjustments easier, but with basic coils it's probably not necessary. You seem to have a good spacing between the inner turn of the primary and the bottom of the secondary. Vertical helical coils are okay, but I'm always afraid the output will strike the primary and cause problems for the transformer. For that reason I usually use flat "pancake" coils for my basic TCs. I think the setup you have now should be just fine. I still think you'll need more turns, but feel free to keep experimenting with what you've got.

Keep us posted on the progress!
Best wishes,
Matt

 

[DerStrom8]

So Marco, how's that coil coming? Any progress?

 

[jrz126]

Whats the manufacturer or part number of your NST?

It looks like you may have a newer solid-state NST. (Found a pic of an identical one here: **broken link removed**)
They operate at high frequency (10-50khz) to generate the voltage, and will not work for a Tesla coil. I made the same mistake when I was gathering parts for my first TC. I think i still have it in a box somewhere.


You should attach your breakout to the toroid/top load, running it with the toroid off will change the resonant frequency.

 

[DerStrom8]

Whats the manufacturer or part number of your NST?

It looks like you may have a newer solid-state NST. (Found a pic of an identical one here: **broken link removed**)
They operate at high frequency (10-50khz) to generate the voltage, and will not work for a Tesla coil. I made the same mistake when I was gathering parts for my first TC. I think i still have it in a box somewhere.

Good catch, Jeff! I don't know how I missed that

The OP mentioned a 50 Hz frequency, but that was probably just the input line frequency. It's very important that the output also be 50-60Hz, otherwise the capacitors will be unable to charge fully on each half cycle. It'll just be going too fast.

Judging by the video, though, the spark gap sounds like the capacitors are operating properly, so I would assume it has the correct output frequency. It's a good idea to check that, though, just to be sure.

You should attach your breakout to the toroid/top load, running it with the toroid off will change the resonant frequency.

While that is true, I have found that a lot of novice TC builders use a topload with way too much capacitance. In my personal experience, I generally found that a smaller (or no) topload at the start is a better way to go, and then increase the size to see if it increases or decreases the output. Usually you can find a nice sweet-spot where the output is at its maximum.

Thanks for your contribution!
Best wishes,
Matt

 

[marcopolo09190]

Hey everyone.

Thanks for asking about my progress Matt. Sadly I haven't had much time and the weather here has been bad so I can't do any more tests on the progress.

I'm now worried about what jrz126 said about my transformer. Will I have a big problem with this or is it fine like Matt said?

Thanks,
Marco

 

[DerStrom8]

Hey everyone.

Thanks for asking about my progress Matt. Sadly I haven't had much time and the weather here has been bad so I can't do any more tests on the progress.

I'm now worried about what jrz126 said about my transformer. Will I have a big problem with this or is it fine like Matt said?

Thanks,
Marco

Hey Marco. Good to hear from you!

Some closer looks at the transformer would be a huge help. It should give you an output frequency on the label. Another thing that will tell you if it's solid state or a classic transformer type is its weight. Is it heavy? Does it feel like you're picking up a brick or a cardboard box? Most NSTs are between 10 and 20kg. A solid state one generally weighs less than half that. It'll give you an idea, anyway.

--Matt

 

[marcopolo09190]

Hey again

Sorry I haven't replied lately, but I've had other stuff going on.

Here's a picture of the transformer label:

View attachment 69132

Also yes it is heavy.

I tested it all the other day in the dark and I just want to say that it looked amazing. Without the toroid, it sparked around 3 - 4" off the top but with the toroid on, it began to spark all across the secondary coil and not off the toroid.

Thanks,
Marco

 

[DerStrom8]

Hey Marco, good to hear from you again!

Arcing along the secondary generally means your topload capacitance is too high. See if you can switch to a smaller topload and see if it helps. It has to be balanced just right. The Tesla Coil Tuner project I linked to earlier will help you find the right L/C balance.

I think the neon sign transformer is fine. If it was a modern high-frequency type, I don't think you'd see any arcing at all.

3-4" is an excellent start. With a little more fine tuning I think you'll be golden!

Good luck!
Matt

 

[marcopolo09190]

Hey Matt

Alrighty, I'll try get a smaller topload.

So I've done some tuning and I think what I'll do is build a bigger primary coil!

Thanks

Marco

 

[marcopolo09190]

Hey Matt

I've built my primary coil and here it is:



Here is one with the original coil for scale:



I hooked it up a couple days ago and tried it out, with a metal pole a couple centimeters from the secondary coil top and no sparks were coming off at all so now I'm really confused.

Help / Advice is appreciated

Thanks,
Marco

 

[DerStrom8]

Hey Matt

I've built my primary coil and here it is:

View attachment 69232

Here is one with the original coil for scale:

View attachment 69233

I hooked it up a couple days ago and tried it out, with a metal pole a couple centimeters from the secondary coil top and no sparks were coming off at all so now I'm really confused.

Help / Advice is appreciated

Thanks,
Marco

Hey Marco, good to hear from you!

As with before, you can't just hook up a primary coil and expect it to work perfectly. Nothing has changed--you still need to tune it.

Since you were getting fairly close towards the end of the first primary, I imagine it would be fairly close to that same point on the second primary. Tuning is the key to making it work at all, and patience helps with that. Go ahead and try moving the secondary connection around and see what happens.

Best wishes,
Matt