Tesla Coil Project - Need Help Please

[marcopolo09190]

Hi Marco.

That looks like the right configuration, yes. Here it is in schematic form:

View attachment 68760

Sorry, I forgot to answer your question. In order to make a musical Tesla coil, you'll really need some sort of solid state control to modulate the input. The output would also have to be directly tuned to the input, which is really only possible with a full solid-state circuit.

Regards,
Matt

EDIT: Oh, and DO NOT connect the secondary ground to the transformer ground. The transformer ground should be connected to mains ground, and the secondary should be earthed. Connect it to a metal stake (1-2 foot, 30cm-60cm) and pound it into the ground.

Ok sweet I'll get round to building a little box for my capacitors and then wire them all up.

Thanks,
Marco

 

[marcopolo09190]

Hi Marco.

That looks like the right configuration, yes. Here it is in schematic form:

View attachment 68760

Sorry, I forgot to answer your question. In order to make a musical Tesla coil, you'll really need some sort of solid state control to modulate the input. The output would also have to be directly tuned to the input, which is really only possible with a full solid-state circuit.

Regards,
Matt

EDIT: Oh, and DO NOT connect the secondary ground to the transformer ground. The transformer ground should be connected to mains ground, and the secondary should be earthed. Connect it to a metal stake (1-2 foot, 30cm-60cm) and pound it into the ground.

Hey Matt.

Here is pictures of my capacitors in their box: https://imgur.com/a/gOgSJ

All I have to do is wire them up. How shall I do that?

Thanks,
Marco

 

[DerStrom8]

Hey Matt.

Here is pictures of my capacitors in their box: https://imgur.com/a/gOgSJ

All I have to do is wire them up. How shall I do that?

Thanks,
Marco

Hey, that looks great! Is the bottom of the box lined with foil? You'll need the caps to be connected in parallel, so connect all the foil parts and connect all the bolt parts. Those will be the two connections to your capacitor bank. Having the bottom of the box lined with foil will help connect the bottoms of all the capacitors.

Keep up the good work!
Regards,
Matt

 

[marcopolo09190]

Hi Matt.

I tested the tesla coil today and the capacitors work great with 6.22nF but I still haven't got a spark coming off the secondary coil. Here are some pictures of the whole configuration:

https://imgur.com/a/Gmmfv

Please help

Thanks,
Marco

 

[DerStrom8]

Hi Matt.

I tested the tesla coil today and the capacitors work great with 6.22nF but I still haven't got a spark coming off the secondary coil. Here are some pictures of the whole configuration:

https://imgur.com/a/Gmmfv

Please help

Thanks,
Marco

Hey Marco. My internet connection is quite slow tonight, so I can't seem to load the photos. I'll take a look first thing in the morning though.

In the mean time, if you could take a video of your coil operating, it might help me to figure out what you'll need to do next. A lot of the time you can tell what needs to be done just by the sound of the spark gap, believe it or not. If that's a possibility, great. If not, we'll go the classic route--trial and error

Anyway, it's past midnight here, so I should be heading to bed. I'll check back on the thread tomorrow morning though.

Best wishes,
Matt

 

[marcopolo09190]

Hey Marco. My internet connection is quite slow tonight, so I can't seem to load the photos. I'll take a look first thing in the morning though.

In the mean time, if you could take a video of your coil operating, it might help me to figure out what you'll need to do next. A lot of the time you can tell what needs to be done just by the sound of the spark gap, believe it or not. If that's a possibility, great. If not, we'll go the classic route--trial and error

Anyway, it's past midnight here, so I should be heading to bed. I'll check back on the thread tomorrow morning though.

Best wishes,
Matt

I'll try get a video tonight

The sound is much louder now with the new capacitors so thats all I can tell you right now I'll get a video done a little later so you'll get to see it when you wake up.

Thanks,
Marco

 

[marcopolo09190]

View attachment 68789

Heres a picture if you can see it

 

[DerStrom8]

Okay, nevermind--the images finally loaded

I have a couple of reservations about the current setup. The first is the spark gap. How exactly is it set up? I see the wires from the coil/capacitors are connected to different bolts than the transformer. Are the top and bottom bolts connected to the same spark gap contact? If not, you should have those clips connected to the same bolts as the transformer outputs (inputs to the tank circuit).

2, have you tried removing the toroid? Or put a breakout point on it? Usually if there's a sharp edge connected to the output, and the coil is connected properly, you'll get a bit of corona coming off the wire or breakout point. Try putting a nail on top of the toroid, or take it off completely. It also may help to test the coil in the dark. Let me know if you see any bluish glow around the output.

Finally, I'd recommend trying to find thicker wires. The ones you have now will probably work, but they're very thin and probably cause a lot of unwanted resistance. They might also allow current to leak through the insulation and into the ground and surrounding objects. You'll want to avoid this if possible. You should probably use closer to 8 AWG wire (not sure of the measurement Down Under). This will help keep the efficiency up.

Also, for future reference, you'll probably have to move the secondary coil connection to the transformer around to get the correct inductance in the primary. This is called "tapping", and it's probably one of the oldest, most used methods of tuning a Tesla coil.

Okay, now it's time for me to go to bed. Good night and I'll check back tomorrow.

Best wishes,
Matt

 

[marcopolo09190]

Okay, nevermind--the images finally loaded

I have a couple of reservations about the current setup. The first is the spark gap. How exactly is it set up? I see the wires from the coil/capacitors are connected to different bolts than the transformer. Are the top and bottom bolts connected to the same spark gap contact? If not, you should have those clips connected to the same bolts as the transformer outputs (inputs to the tank circuit).

2, have you tried removing the toroid? Or put a breakout point on it? Usually if there's a sharp edge connected to the output, and the coil is connected properly, you'll get a bit of corona coming off the wire or breakout point. Try putting a nail on top of the toroid, or take it off completely. It also may help to test the coil in the dark. Let me know if you see any bluish glow around the output.

Finally, I'd recommend trying to find thicker wires. The ones you have now will probably work, but they're very thin and probably cause a lot of unwanted resistance. They might also allow current to leak through the insulation and into the ground and surrounding objects. You'll want to avoid this if possible. You should probably use closer to 8 AWG wire (not sure of the measurement Down Under). This will help keep the efficiency up.

Also, for future reference, you'll probably have to move the secondary coil connection to the transformer around to get the correct inductance in the primary. This is called "tapping", and it's probably one of the oldest, most used methods of tuning a Tesla coil.

Okay, now it's time for me to go to bed. Good night and I'll check back tomorrow.

Best wishes,
Matt

Heya Matt

1. Top and bottom bolts are connected to the same spark gap so don't worry bout that.

2. Yes I did, and that hasn't changed anything either. I did place a metal pole stuck into the ground close to the secondary coil wire and that gave a small spark but nothing special.

Do you mean thicker wires for connecting everything? Would you say thats the main problem because I'd rather not change all my wiring if I don't have to if you understand.

And what do you mean by moving the secondary coil connection to the transformer around to get the correct inductance in the primary?

Have a good sleep

Thanks,
Marco

 

[DerStrom8]

Heya Matt

1. Top and bottom bolts are connected to the same spark gap so don't worry bout that.

2. Yes I did, and that hasn't changed anything either. I did place a metal pole stuck into the ground close to the secondary coil wire and that gave a small spark but nothing special.

Do you mean thicker wires for connecting everything? Would you say thats the main problem because I'd rather not change all my wiring if I don't have to if you understand.

And what do you mean by moving the secondary coil connection to the transformer around to get the correct inductance in the primary?

Have a good sleep

Thanks,
Marco

Hello Marco.

The thin wires definitely don't help, but they're not the main problem.

I didn't say move the secondary coil connection, I said move the connection from the secondary of the transformer around the primary coil. I actually should have said to move the outside connection--I'm not sure if that's the wire from the transformer or from the capacitor.

I know I'm not making much sense here, so I'll try to rephrase it. Your primary coil has an inside end and an outside end. The inside end should stay where it is, but the outside connection can move. If you move it every quarter or eighth turn at a time, you'll hopefully find a "sweet spot" where it'll work. And it goes without saying, DO NOT MAKE ADJUSTMENTS WHILE THE COIL IS PLUGGED IN!!!

If you try tuning it this way and still can't get it to work, you'll probably want to increase the size of the primary. There may not be enough there, but we'll wait and see.

If you don't want to go through all this trouble, you can build a Tesla Coil Tuner for pretty cheap. It'll help you figure out where to tap things, and even find the resonant frequency of your secondary coil/topload. If you can figure out how to read it, it's very useful.

Best wishes,
Matt

 

[marcopolo09190]

Hello Matt

I've done some testing with the tesla coil and I'll let you hear it for yourself with this video:

Can't wait for your reply

Thanks,
Marco

 

[()blivion]

First of all, IMO you should be a bit more careful when approaching the primary of your Tesla coil, especially after it was just powered on. They have been known to kill people. It is the BEER BOTTLE CAPACITORS and it's built up charge that will kill you. Luckily for you, there is no rectifying diode coming from the HV transformer, or the caps may not have discharged seconds before you switched it off THEN IMMEDIATELY TOUCHED THE CAP WIRE.

Bad bad habit IMHO.

As I go farther in, the spark will get shorter and shorter. . .

You need to find the resonant frequency. The farther you get away from it, in either direction, the lower and lower the power will be. What you should do is rather than skipping one whole loop at a time, you should go AROUND each loop, starting from the longest distance and move slowly in. Start by going about 1/8 a turn at a time and note the part that works best. When you find it, move the wire a bit up and down from that point. When you hit the right location on the primary coil, you should see a big spike in performance, THAT is the resonant point and where you should attach your wire.

The better way would be to build the tool DerStrom8 suggested. Very useful for what you're doing.

 

[DerStrom8]

Hey Marco. Thanks for the video.

Your spark gap sounds like it's getting hot and conducting to easily, for one thing. This can happen when the contacts are too close. You might try spreading them out a bit more, or adding more contacts. It should sound more like a high-frequency "pow pow pow", rather than a crackle. Other than that, you are probably correct--it looks to me like you'll need to increase the size of your primary coil. ()blivion is correct, however, in saying that you should probably tune it by moving around a quarter or eighth of a turn each way, rather than jumping an entire turn.

()blivion, residual charge in the capacitors is not as much of an issue with AC tesla coils as it is with DC ones, but you have a point. Marco, I would recommend you short the spark gap before going to touch the primary or capacitor setup. This will discharge the caps through the primary, eliminating any residual charge.

Anyway, ()blivion is right on. You'll know it when you've reached the resonant frequency, but at this point to me it looks like you'll need to widen your spark gap and get a larger primary.

By the way, the spark gap should be positioned so it can just barely spark. By this I mean set it up so that if it's widened even a tiny bit, it won't fire. Have the distance set so it just barely conducts. This will allow the maximum transfer of energy.

Otherwise, looking good!
Keep me posted!
Regards,
Matt

 

[gary350]

This is a pretty long 6 page novel I skimmed through it. It looks like your getting some ok help. Here is my 2 cents worth.

Looking at the photos I would say you need more turns on the primary coil it should have about 15 turns.

Secondary coil needs 950 turns no matter what diameter it is. #24 wire works great for 4" PVC pipe.

The spark gap needs a fan. Minimum requirement is a cooling fan. Best choice is a vacuum cleaner fan with a variac to adjust the speed.

Be sure to use larger wire on the capacitor bank when they discharge there is a lot of current that needs to travel through the wires.

Glass bottle caps are only about 30% efficent you will have about 70% power lose. There are several people selling caps on ebay I buy my caps from some of these ads. **broken link removed**

You could buy some TC plans on ebay. Good plans that really work NOT photo copies of magazine articles.

**broken link removed**

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This is my 10" coil it produces 12 foot streamers on 12KW.

 

[()blivion]

()blivion, residual charge in the capacitors is not as much of an issue with AC tesla coils as it is with DC ones.

Yup, I'm aware.

I would recommend you short the spark gap before going to touch the primary or capacitor setup.

I agree, I would also like to add that OP should possibly use a "chicken stick" discharging rod. A chicken stick is something that is non conductive, like a small diameter 3~4 foot length of PVC and has a bit of wire on the end, but ONLY on the end. Then you make two points on you capacitor bank that you can touch easily with the metal end of the chicken stick. This gives you one of the safer ways to work with HV... Distance. If your not near the dangerous parts it's much harder to get shocked. Another way is make your spark gap have a switch that does the same.

Then again, this is a pretty extreme measure for a small AC Tesla coil. You're probably safe without it. It's still a good thing to get used to. Whatever you do, make sure it's not a length of metal or something for a handle. That would kinda defeat the point.

 

[DerStrom8]

This is a pretty long 6 page novel I skimmed through it. It looks like your getting some ok help. Here is my 2 cents worth.

Looking at the photos I would say you need more turns on the primary coil it should have about 15 turns.

Secondary coil needs 950 turns no matter what diameter it is. #24 wire works great for 4" PVC pipe.

The spark gap needs a fan. Minimum requirement is a cooling fan. Best choice is a vacuum cleaner fan with a variac to adjust the speed.

Be sure to use larger wire on the capacitor bank when they discharge there is a lot of current that needs to travel through the wires.

Glass bottle caps are only about 30% efficent you will have about 70% power lose. There are several people selling caps on ebay I buy my caps from some of these ads. **broken link removed**

You could buy some TC plans on ebay. Good plans that really work NOT photo copies of magazine articles.

**broken link removed**

**broken link removed**

**broken link removed**

**broken link removed**

This is my 10" coil it produces 12 foot streamers on 12KW.

Hey Gary, thanks for your 2 cents!

The number of turns on the secondary doesn't have to be exactly 950. Anywhere between 600 and 1200 turns should work, though a higher number of turns introduces more resistance. My miniature Tesla coil has only 100 turns and works beautifully (for its size). It's important to remember that it's not the number of turns that's important, but that you can match the resonant frequency with the tank circuit.

As for the fan, that's a good idea. It's not absolutely critical in order for the coil to work, but it helps the spark gap from overheating and conducting too easily. Marco, you could probably place a 12v CPU fan on top of the PVC used for the gaps, but make sure it's well-insulated from the high voltage circuitry.

The larger wires, as I mentioned before, are also a good idea. Marco, I think once you get it tuned, you should definitely find some thicker wires designed for high voltage. You're probably leaking quite a bit of energy through the thin insulation and into the ground. If you ran the coil in complete darkness, you'd probably see parts of the tank circuit glowing and sparking where it shouldn't. Cables designed for hv would most definitely help.

It's true that beer bottle capacitors are inefficient, but they work well enough for hobbyists who just want to build a working Tesla coil without spending a fortune on parts. Buying capacitors online can get very expensive, especially for a student building one for a science project. That is the only reason I suggested them instead of telling him to buy professional ones.

You can get Tesla coil plans on google for free. You don't need a kit and/or real plans. If yo ask me, plans take away all the fun of building a TC. The fun part is creating one with your own stuff and making it work by yourself. When you build a Tesla coil by yourself (without plans), you can truly call the result "your own", and it just feels much better than building one from plans.

Thanks for the pics Gary!

Regards,
Matt

 

[()blivion]

You can get Tesla coil plans on google for free. You don't need a kit and/or real plans. If yo ask me, plans take away all the fun of building a TC. The fun part is creating one with your own stuff and making it work by yourself. When you build a Tesla coil by yourself (without plans), you can truly call the result "your own", and it just feels much better than building one from plans.

Well said.

 

[tvtech]

Hi Matt

You know your Tesla stuff. Great guidance and all here in/on this Thread.

Regards,
tvtech

 

[DerStrom8]

Hi Matt

You know your Tesla stuff. Great guidance and all here in/on this Thread.

Regards,
tvtech

Thanks tvtech I also want to thank Unclejed613, ()blivion, and Gary350 for their input. They've definitely been helping here and I appreciate that they've been filling in all the blanks I've been leaving

 

[gary350]

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.

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.