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FrozenGate by Avery

Tesla Coil Build Thread

I always feel a mixture of jealousy and shame when I see amazing professional looking builds like yours.

It is quite depressing to have to work with very limited equipment (no power tools/saws), space, and supplies. Even the base you made for your coil looks amazing and is far out of my build capacity (I know how, but don't have the facilities to do it). Your primary looks gorgeous! I had to hand spiral my primary with no former/supports and it didn't come wound in a nice neat coil to begin with. I had to hand wind my secondary with no jig, haha.

The old adage is true; garbage in = garbage out. I'm still amazed my coil works at all, much more so that it works as well as it does.
 





Sig, you do realize that you don't necessarily need good machinery to build a decent coil right?

Improvision is a heavy part of all hobbies, and electronics are no exception by any means.

Making do with what you have will almost always work perfectly fine. And in some cases you might find something innovative during your improvisions. :)

Also, think about what Tesla had to use when he created his coils.
 
Haha, I know it isn't necessary to get it to work, but that doesn't mean it isn't easier to get it to work well with better equipment.

Here is the perdicament I am in with my SGTC and why it is remaining AS IS for the forseeable future. (I am moving to work with much smaller SSTCs as the primary is wound directly on the secondary and much lower voltages are involved. The electronics is largely unaffected by physical placement variables as long as symmetricality and low stray/leakage inductance is maintained.)

To get the most out of my coil I would need to increase the coupling factor between the primary and secondary coil. This means I would have to raise the primary coil up vertically. Since my primary is unsupported (it just sits on a lexan sheet) I cannot raise the primary any. The reason it is sitting on a lexan sheet with no supports: I can't purchase the thick plastic needed for supports here, and I only have small hand tools at my disposal (a single 5" coping saw and cordless drill) so even if I could purchase the material, I have no way of cutting/milling it.

I also need to add a larger topload to stop the parasitic breakout from the HV side of the secondary, but I can't since my Primary doesn't have enough turns to tune to a larger topload. I would also need to increase the inside diameter of the primary coil (remove turns) to prevent and stop primary-to-secondary-base arcing, and add a couple more turns to the outside of the primary coil to both compensate for the removal of interior turns and to increase the tuning range. The largest width of wood/lexan base I can purchase is 2ft, which the current plywood/lexan base is. My primary is already 23" in outer diameter, so adding turns would cause it to extend past the edges of the base - dangerous. So increasing primary diameter would also require me to find a new base for my coil, and matching insulators (lexan sheets).

The hardware store here cannot cut square edges on PVC pipe also (they are limited to a ~70degree angle from the axis of the pipe), and I obviously don't have the facilities to cut it myself. They also cannot make lengths accurate to less than 1/4" of an inch (one piece would be 10.25" another would be 10" etc). So, where as most people use PVC pipe + end caps to make base supports, I am again unable.
 
Don't feel bad at all
My coil is 30 years of dreaming, 5 years of planing and 6 months in construction !

The base is made out of a cable reel with PVC stands
the MOT supply is because NST's are so fragile
the primary tubing came in a coil and I made the supports out of a cutting board
The secondary was wound in 30 minuets using a drill and a shelf bracket and variac
the top load is dryer duct with aluminum tape

This is your first coil you should be proud of what you have done!
 
Amazing Coil nospin :D .

Heres a randome one i made today , VTTC in design .

Secondary is only 7cm high 5cm diamiter with 6cm worth of windings .

Output at 250W in is bushy arcs about 1" in length and no reddening of anode ,
at Full power unlimited are 3-4" Long But tube reddend quicky .

There was no tuing i just used ruff ideas from othere coils and that , after tuning i should get a better lenght arc and less reddening of anode :)

thought id share .


SAM_0510 by TwirlyWhirly555, on Flickr


SAM_0527 by TwirlyWhirly555, on Flickr


SAM_0520 by TwirlyWhirly555, on Flickr
 
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Nice results!!
Have you tried any toploads on it?
What is full power?

nospin
 
Wow!! That is a beautiful coil!

Let me guess, you're using older Sanyo MOTs? Big dudes from the late 1980's to early 90's? correct?

I always found these bigger mots allowed better performance even when 2.5x their rated insulation voltage. I built a 6 pack mot supply from those and popped their shunts out
to allow better cooling. 12Kv @ 0.67A - peaks of up to .8A. Too much for my breaker to handle.
 
The MOT's are the biggest I had out of 10
the shunts are intact but mine are super cooled and insulated in an oil bath
just like pole pigs! "See the pictures"

This is about the most efficient coil you will find! :D
 
nospin said:
Nice results!!
Have you tried any toploads on it?
What is full power?

nospin
Click to expand...

Very nice SGTC Sigurthr look foward to seeing SSTC :)

Thanks :D

After adding anothere 6 turns on primary i now have better results and less heating , there is a topload on it at the moment its just a pice of tine foil .

After a arc over i remade the secondary and used a small lemoade can base as the topload and i have it running pulsed via a mosfet in cathode to ground .

My latest is i have now got the coil running from smoothed DC and is pulsed via a relay in cathode insted of mosfet , but after a few minuits at full power it arced over and messed up seconday and primary . Not sure on full power draw didnt think to messure it :D

This is halfwave pulsed setup

Mini Tesla Coil V3 Pulsed . - YouTube

This is full wave DC running

mini tesla coil V3.2 CW Full wave Supply . - YouTube

And Full wave DC Pulsed running

Mini Tesla Coil V3.3 CW DC supply , Pulsed . - YouTube
 
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Haha, do you mean my big one or the lil one I whipped up in my last post? XD Thanks either way.

I love CW VTTCs/SSTCs! The bushy hot arcs are awesome. I'm not particularly fond of the QCW style or sword like arcs. Branchy or bushy all the way, hehe. My SSTC will be CW and interrupted CW (pulsed like you did). I don't think it will run too long on CW without getting quite hot though, it really stresses the components.

Ya, I was wondering how that 100V FET was surviving, haha. I would leave the cathode to ground connection continuous and try switching the screen on and off instead. I'm not sure what voltage your screen sits at though, but it should be less than cathode to ground IIRC. You could also try anode modulation, but I don't know how it is done to advise you any. I never worked with valves really.

I've enjoyed all your videos, keep them coming!
 
Sigurthr , Thanks :D Hehe Both Coils you have made are great i have yet to make a SGTC i kinda jumped to VTTC's insted :D . I Love the CW Coils to just looks so much cooler downside is as you said stresses the components , unfortuanly if i try and pulse the VTTC in CW mode i get massive voltage spikes that jump from secondary to primary and destroy them i have made my primary and secondarys 5 times now :P .

nospin , Thanks :) , i messured power draw and at full power i get 11 - 12cm Arcs CW and it pulls 4.5 Amps @ 230v so just over 1Kw in :D
 
You might need to alter your resonator design so that both the primary and secondary are on sturdier coilforms, such as 1/4" wall PVC pipe or suitable glassware.

Also generally what I've gathered is that for CW operation one would first operate the coil with a PWM interrupter at a high rep rate and vary the pulse width to find the maximum permissible operating "power" (duty cycle) for long life. Then you scale back the input power via variac while in CW mode to match the duty cycle ratio found with the PWM interrupter. For example if you find that a 40% duty cycle / pulse width is the max you can run it on with the interrupter, you would then set the variac to 40% input power when running on CW, and this in theory should allow the coil to safely run CW.

Other coils which have been built with CW in mind during design and construction obviously don't need this limiting, but there is always a trade off.

My mini resonator should withstand 750W no problem as long as I get some 8 or 10ga wire for the primary and use enough that current is limited to <5A. The secondary should do just fine as is as long as I get the coupling ratio correct to reduce inductive heating. So for me at least it is mostly a matter of primary adjustments, which in a helical system is the easiest part to adjust.
 
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