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I made a Tesla coil which does not show discharge, please help

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NoobMD

Thu Apr 22 2010, 12:43PM

Registered Member #2818 Joined: Thu Apr 22 2010, 12:14PM
Location:
Posts: 4

allright, so i made a tsla coil. specs are below: oh, i made 2 primaries(one helical and one inverted conical). i use the helical one
1. Secondary one-
Radius-1 inch
Height - 19.8 inches
No. of turns - 900
Wire Dia - 0.019685 inches
Height - 9.875 inches (to increasecoupling coeffiecient)
2. Primary - Inverted Conical One-
Radius 1 - 2.25 inches
Radius 2 - 4.5 inches
Height - 4 inches
No. of turns - 4.25
Wire Dia - 0.3125 inches
3. Primary - Helical one
Radius 1 - 3.946 inches
Radius 2 - 9.46 inches
Height - 9.875 inches (to increase couling coefficient)
No. of turns - 7
Wire Dia - 0.375 inches

Capacitors - Used 17 Snapple bottles as leyden jar capacitors
Dimensions of the bottles -
Diameter - 2.791 inches
Height - 5.492 inches
Thickness - 0.0803 inches
Dielectric Constant - 7.75 (soda lime glass
Right.
so this is the circuit - capacitors in prarell with the the key and the primary. the secondry base is grounded and the top is connected to two toroids on top of each other-
Toroid 1 - Minor Dia - 1.65 inches
Major Dia - 6 inches
Toroid Height - 22.5 inches
Toroid 2 - Minor Dia - 1.65 inches
Major Dia - 8 inches
Toroid Height - 24 inches
Now static gap design -
2 electrodes with dia - 0.116 inches and the distance of seperation is 0.02756 inches.
So the thing is that whenever i switch it on nothing happens, the spark gap fires up, capacitors are working (verified) but there is no discharge on the toroid, so i fed this data into javatc which showed me a 50% detune. so i made the no of turns 2.5 and radius decreased to 7 from 9.46. then i fired it up(javatc showed 2.5%detune), and it faintly lit a fluorescent but there still was no discharge. so can u please help me out and tell me what is wrong with this set up and how i can fix it.

ohh... i forgot the transformer- its a 9kv 30mA NST with an input voltage of 220V

[Edit: Less shouting]

raff

Thu Apr 22 2010, 02:06PM

Registered Member #2315 Joined: Tue Aug 25 2009, 02:35AM
Location: Leyte, PH
Posts: 161

post some pictures

NoobMD

Thu Apr 22 2010, 02:25PM

Registered Member #2818 Joined: Thu Apr 22 2010, 12:14PM
Location:
Posts: 4

right. about that. me and interloper are working on the same coil together.
the pictures are there:

the setup is now different. we removed all of the excess wiring, all of it and we are using a helical coil with AWG 00 wire which is 0.378 inches in diameter. and we are using 17 salt water capacitors instead of the 12 which are all connected in parallel.

raff

Fri Apr 23 2010, 01:18AM

Registered Member #2315 Joined: Tue Aug 25 2009, 02:35AM
Location: Leyte, PH
Posts: 161

have you tried swapping the primary coil connections?

NoobMD

Fri Apr 23 2010, 08:04PM

Registered Member #2818 Joined: Thu Apr 22 2010, 12:14PM
Location:
Posts: 4

yeah, thre is a slight different, there is a slight discharge when we bring tubelight near the toroid. but they still dont resonate at the same freq. can u tell me why?

ScotchTapeLord

Fri Apr 23 2010, 11:54PM

Registered Member #1875 Joined: Sun Dec 21 2008, 06:36PM
Location:
Posts: 635

Because it isn't tuned. I just looked at one of your later pictures and there doesn't even appear to be a movable tapping point on the primary as there was in the earlier one. I hope you aren't completely relying on your program's calculations for where to connect the primary.

If your primary is long enough, there exists one point on it where if tapped will produce the best results. Your program cannot find it. You have to. You have to tune it! Move the tap point around until you get output (make sure the coil is off when you do this). It's going to take a while.

And now for the terrible analogy: You're at the end of your journey and you can't find find the doorknob to your final destination... you have to feel around for it. :D

Good luck, looking forward to seeing some sparks!

NoobMD

Sat Apr 24 2010, 06:38AM

Registered Member #2818 Joined: Thu Apr 22 2010, 12:14PM
Location:
Posts: 4

Dude, i tapped it everywhere i could but no sparks

ScotchTapeLord

Sat Apr 24 2010, 08:08AM

Registered Member #1875 Joined: Sun Dec 21 2008, 06:36PM
Location:
Posts: 635

The slight discharge you mentioned earlier, does it change at all when you tap it at different points?

Maybe you should try it without the topload. This will lower the power requirement for breakout, and will help deduce whether the problem is tuning or something else. It will also raise your frequency quite a bit, so be prepared to tap literally everywhere...

Although, if the problem is too much stray inductance in your primary (like between your primary and your capacitors! This is caused by long, thin wires... so use thick, short ones), then you may not be able to reach the resonant frequency of the bare secondary.

There are only a few problems that I can think of:
Tuning,
Stray Inductance,
Secondary Fault

The last one is really the worst case. If you have output, it's unlikely.
You mentioned that the secondary is grounded, which is good, but what is it grounded to, and how long is that connection?

raff

Sun Apr 25 2010, 04:12PM

Registered Member #2315 Joined: Tue Aug 25 2009, 02:35AM
Location: Leyte, PH
Posts: 161

I suggest making a rolled film/foil cap. Hvwiki has some info regarding said capacitor...

Herr Zapp

Sun Apr 25 2010, 10:10PM

Registered Member #480 Joined: Thu Jul 06 2006, 07:08PM
Location: North America
Posts: 644

NoobMD -

Please help us understand the situation with this coil:
1. First, "interloper" was working on it, and started a thread on this forum titled "Tesla coil help" back on April 14th.
2. After getting numerous responses to his questions, interloper suddenly "disappeared", with his last post dated April 21.
3. On April 22, you started a new thread titled "I made a Tesla coil which does not show discharge, please help", which is apparently the same coil as interloper was working with.
4. Is interloper gone? Have you assumed control of this coil?
5. Did you read and understand all the responses to interloper's questions on his "Tesla coil help" thread?
6. I posted a series of questions on the "Tesla coil help" thread on April 21 that were answered; would you take the time to read those questions and provide some answers? Without specific information (and the requested photos) it's impossible for anyone on this forum to help you effectively troubleshoot the reasons your coil doesn't work.

Just because you've tried tapping the primary at multiple points ("Dude, i tapped it everywhere i could but no sparks") just gives more evidence that your primary and secondary systems may be wildly out-of-tune. If the resonant frequencies of the primary and secondary are grossly mismatched, there is no way that you can tune the primary to match the secondary, regardless of where you tap it. The only way to get your coil tuned is to know the approximate resonant frequencies of the primary and secondary systems. The only way to do that is to either actually measure the frequencies, using test equipment, or to calculate them, using careful physical measurements and a design tool like JAVATC.

So, to start, please go back to the "Tesla coil help" thread and answer the questions from April 21. Lets try to eliminate any obvious design or construction problems first, then move into possible tuning problems.

Regards,
Herr Zapp

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