Author Topic: Tesla coil Build comparison. (Proof of ability) (Read 32628 times)

TinselKoala · « **Reply #15 on:** August 17, 2014, 11:48:25 PM »

@Farmhand:
My "grownup" Tesla coils, all different, all showing different principles:
#0: A 2 kW-class monster with rotary spark gap, big NST primary supply, safety gap, chokes, an Amplifying Transmitter (second secondary) coil, the whole nine yards. Haven't run it in years.
#1: A SolidState coil using TL494, a current driver, trifilar phase transformers, mosfet H-bridge.
#2: Major improved version of above with low-aspect-ratio resonator and double chromedome top capacity.
#3: SassyClassE SSTC: a low-aspect-ratio Class E single-mosfet DC-input SSTC, a real field-pusher.
#4: TKSlayer, my version of the Slayer Exciter simple low-voltage SSTC using NPN power transistor.
#5: MOT-DC Blown Gap SGTC, a unique single-MOT, HV FWB-rectified, compressed-air-quenched spark gap coil, 1 kW class, running at about 1.5 MV, actually.
#6: TKMiniSlayer, a bottom-loaded, tunable miniature version of the Slayer SSTC, using NPN power transistor, a field pusher.
#7: TinselKoil VII, the present design, a 'design proof-of-principle' built according to calculated parameters to see if they really worked, a hybrid SS-SG coil. DC input of 24 volts, ZVS dualing mosfet flyback driver at 30 kHz, flyback feeding traditional SGTC design with 4 nF SrTiO tank caps and 8-9 uH primary, ringing a loosely coupled secondary of 975 turns of #27 at somewhere between 600 and 800 kHz. The calculator used to design the coil says it should reach 1.15 MV at the top of the resonator (when fully tuned of course!)

ETA: Can you believe it? I forgot one, about #0.5, the portable transmitting plant that I use for a logo sometimes. It's in a crate on a high shelf.

Off to the bathroom to do some more runs... Coil runs I mean, silly!

How's THIS for "Overunity in VARs".....

The calculated theoretical VI profile of the 24-volt input TinselKoil VII:

TinselKoala · « **Reply #16 on:** August 19, 2014, 12:53:40 PM »

Getting there:
http://www.youtube.com/watch?v=jsfW6tT3cQA

TinselKoala · « **Reply #17 on:** August 20, 2014, 07:59:09 PM »

Making progress... this is just a test of the GIF animator... if it doesn't run inline please download and watch...

Not bad for 24 volts input, there are some streamers over 12 inches in there.

ETA: OK that didn't work, so here are some stills.

TinselKoala · « **Reply #18 on:** August 21, 2014, 07:10:11 PM »

Erratum: At about 2:05 I say "drains" when it should be "sources" that the negative rail is connected to.
http://www.youtube.com/watch?v=d_VtbfhyvUU

Farmhand · « **Reply #19 on:** August 21, 2014, 09:12:11 PM »

Nice, it has those smooth silky discharges like flames. I like it.

..

Kamil · « **Reply #20 on:** August 21, 2014, 11:16:40 PM »

Hi Guys,
For last two years I have experimenting with Tesla coils but always kept them small size ,powered by flyback which was nice and fun but now I feel like I like to move forward and build some think bigger but relatively easy just to keep cost down.
I have few MOTs and thinking about useing them as a power supply for my new project.
Can you give me some advice plus schematic which will be best to start with building big Tesla coil ?

P.S. You can visit this website:
http://isparktube.com/ is really good and I have posted there few of my projects

Regards

MenofFather · « **Reply #21 on:** August 22, 2014, 09:46:06 AM »

Quote from: TinselKoala on August 20, 2014, 07:59:09 PM

Making progress... this is just a test of the GIF animator... if it doesn't run inline please download and watch...

Not bad for 24 volts input, there are some streamers over 12 inches in there.

ETA: OK that didn't work, so here are some stills.

That curent is consumptio?

tinman · « **Reply #22 on:** August 22, 2014, 10:10:27 AM »

Nice build there TK.
I bet that would light some CFL's.

TinselKoala · « **Reply #23 on:** August 22, 2014, 03:45:26 PM »

Quote from: MenofFather on August 22, 2014, 09:46:06 AM

That curent is consumptio?

I have not yet been able to measure the current draw because it makes my digital meters freak out and I can't seem to find my moving-coil ammeter in all this clutter, if I even still have one. I know several ways to do it but they require some setting up and I've been too busy and lazy to do it. Past experience says that the driver will draw up to 7 amps when a heavy flyback output is demanded. I am using 2 Sealed Lead Acid 12V batteries of 5 A-H capacity each and they are lasting a surprisingly long time so I think that the draw must be less than 7 A most of the time.

TinselKoala · « **Reply #24 on:** August 22, 2014, 03:48:09 PM »

Quote from: tinman on August 22, 2014, 10:10:27 AM

Nice build there TK.
I bet that would light some CFL's.

It does indeed, lights up the ones in the bathroom fixtures dimly. I haven't yet tried it with the bare bulbs and etc. But I have found that big sparking coils aren't as efficient as what I call "field pushers" which don't produce visible psarks. By turning the spark gap down to tiny gaps (hard to do with this type) while avoiding power arcs, one can make a sparker into a field pusher and get more range on the E field effect like lighting CFLs with no circuitry at a distance.

TinselKoala · « **Reply #25 on:** August 22, 2014, 03:52:27 PM »

Quote from: Kamil on August 21, 2014, 11:16:40 PM

Hi Guys,
For last two years I have experimenting with Tesla coils but always kept them small size ,powered by flyback which was nice and fun but now I feel like I like to move forward and build some think bigger but relatively easy just to keep cost down.
I have few MOTs and thinking about useing them as a power supply for my new project.
Can you give me some advice plus schematic which will be best to start with building big Tesla coil ?

P.S. You can visit this website:
http://isparktube.com/ is really good and I have posted there few of my projects

Regards

If you are building a Big TC then Farmhand will probably be able to help you more than I can. Lately I have been going in the other direction, my next one will be tiny.
My MOT-DC coil is probably unique in that it uses a single MOT, a HV full wave bridge, and is able to make 18 inch streamers using only the 2 kV output of the single MOT. Most MOT coilers use two MOTs in series to get decent voltage output for the TC tank circuit and they don't rectify the MOT output, I think.
MOTs are far more dangerous than the Neon Sign Transformers, even though they are lower voltage, because the MOTs aren't current-limited. You can do a lot of damage in a hurry, with a MOT.

TinselKoala · « **Reply #26 on:** August 22, 2014, 03:56:40 PM »

A couple more videos:

http://www.youtube.com/watch?v=T2JWGNCvh80

http://www.youtube.com/watch?v=SXsChNrBn5I

The spark gap performance is the key to success. Winding the coils is easy, tuning to resonance not too hard... but getting the spark gap to work properly is tricky. Each type has its own quirks. Much of Tesla's creative effort at one time was devoted to spark gaps and other kinds of circuit interruptors.

Kamil · « **Reply #27 on:** August 22, 2014, 04:36:33 PM »

Quote from: TinselKoala on August 22, 2014, 03:52:27 PM

If you are building a Big TC then Farmhand will probably be able to help you more than I can. Lately I have been going in the other direction, my next one will be tiny.
My MOT-DC coil is probably unique in that it uses a single MOT, a HV full wave bridge, and is able to make 18 inch streamers using only the 2 kV output of the single MOT. Most MOT coilers use two MOTs in series to get decent voltage output for the TC tank circuit and they don't rectify the MOT output, I think.
MOTs are far more dangerous than the Neon Sign Transformers, even though they are lower voltage, because the MOTs aren't current-limited. You can do a lot of damage in a hurry, with a MOT.

Thank you TinselKoala for getting back to me.

I visited your You Tube channel and I have to say that I'm impressed with your experiments.
Because you have experience with Bid TC I will appreciate if you advice me on how to build spark gap for my MOT to make it right and SAFE , and how to protect my secondary from over arcing because I heart that you can damage your coil in seconds if is not properly earthed .
Will you be able to give me schematic with good details or any from google will do ?
Thanks in advance .

Kamil

Farmhand · « **Reply #28 on:** August 22, 2014, 09:10:01 PM »

Kamil, Very wise to be safe, I always consider safety first and every part of the primary circuit with MOT's in it is potentially
deadly. When I'm experimenting with anything to do with deadly charge on capacitor or high powers at dangerous voltages
I get myself into a routine where I turn off and disconnect the supply, then discharge all the capacitors and jumper them (shorted)
before even considering touching anything, distractions can be dangerous too.
I have 40 uF on my two MOT's to correct the power factor, which can be left with charge on them sometimes, they get 240 volts.
My primary capacitance is small because less than 20 nF due to my fairly high frequency around 760 kHz, that 20 nF gets charged
to almost double the voltage of the output of the two MOT's in series because I use a DC resonant charging circuit, without that
almost doubling of the 4000 v or so to about 7000 v my spark gap doesn't work so good, I think because of the low capacitance
and energy of the primary capacitor bank.

Building Tesla coils is kind of a very customized thing for most, people build them for different reasons.

Spark gaps are not a strong point for me as I lack a lot of equipment and live out of town. I had to build a wooden frame rotary
spark gap to get a good output from mine. As I just found out the rotor I made from a plastic cutting board for the spark gap is
cracked now so I'll need to make a new gap of some kind.

Almost impossible to build a "safe" Tesla transformer. It's the operator who needs to be safety minded and careful.
I've got my input power restricted by a coil in series with the MOT's that has a fair bit of resistance, my next play with it
will be to remove or reduce the power restriction and fix my spark gap or build a new one, it could do with a better frame
and rotor.

..

TinselKoala · « **Reply #29 on:** August 22, 2014, 10:47:16 PM »

Yep, all of the above. Safety first, and a MOT is no toy, my small 1 kW MOT coil scares me even more than my full on 2kW NST coil.

Meanwhile, I really didn't like the look of TKVII with that white pvc form for the primary coil, so I made a more traditional "basket" form out of some mahogany plywood. It looks a lot better I think and is certainly more "classic" in appearance.

I also temporarily installed the ground electrode to see what kind of gap breakdown I would get. It spans the 15 cm gap easily enough, but not larger at the moment. So I am guesstimating only about 500 kV output.

Of course the electrode detunes the thing fairly drastically.

http://www.youtube.com/watch?v=aIZClhoU2Xk

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