Tesla Coil Build Thread

[nospin]

one microwave and your in, free!

I made a 2.8kw coil with two

I don't use NST's for a reason

 

[USAbro]

The cap arced through because the dielectric wasn't thick enough to withstand the voltage, it will still hold a charge at voltages lower than the punch-through voltage. It is unsuitable for tesla coil work, and a fire hazard for anything else now. Toss it. I believe I said earlier the plastic should be around 1mm thick per layer.





He has a point; the MODs I tested a while back were pretty capacitive to tens of KHz. I only have one left but if need be I can test it on my 30KHz supply. They won't die from it because they have much higher reverse breakdown voltages and forward current ratings than the application requires, but they'll still pass a fair amount of reverse current from a 16KHz supply. Another issue all together is the forward voltage drop on those diodes can be rather hefty, tens of volts at minimum, and I think his ballast only puts out 30V under load. After the Vdrop it's likely he'd see essentially no current flow once loaded.

Oh, okay. It was like less than 1mm thick.

Another question. Can MOT's be wired to 120v mains to there primary? And that can be wired directly into the circuit? Are they enough voltage with just one of them? Two of them may be kind of hard to get.

 

[nospin]

1 MOT will work perfect on 120 volt and is good sized for your secondary

 

[USAbro]

Thanks. So how many wraps of wire should the primary be? Is the primary I showed in the pictures several posts back good enough?

If I used these caps https://www.youtube.com/watch?v=ACJCUPtCV3I and one mot and my current configuration, with a static spark gap but multiple gaps and a fan blowing on the gap, and two 10 inch pie pans as the topload, would it probably produce at least 6 inch are that spontaneously jump off the breakout point?

 

[The Lightning Stalker]

Get a can of spray adhesive and stick Al
foil, or better yet gutter flashing, to the
plastic. That is how I did my first glass
plate capacitors.

Don't MOT coils NEED a rotary gap because
of the high current?

Why don't you just get another flyback
transformer?

 

[nospin]

Thanks. So how many wraps of wire should the primary be? Is the primary I showed in the pictures several posts back good enough?

If I used these caps https://www.youtube.com/watch?v=ACJCUPtCV3I and one mot and my current configuration, with a static spark gap but multiple gaps and a fan blowing on the gap, and two 10 inch pie pans as the topload, would it probably produce at least 6 inch are that spontaneously jump off the breakout point?

That primary looks fine, I would use a sigle gap but you need more airspeed thru the gap, most narrow down to 1 to 1.5 inch at gap and use vacuum power

Google: sucker gap tesla

 

[USAbro]

I was thinking of taking 4 inch pvc pipe with two bolts screwed in the side for the spark gap. And then using a computer fan in the bottom to keep it cool. Would that work? Or would the bolts melt?

@The Lightning Stalker-The flyback uses high frequency and I'm hearing it won't work, besides, getting another TV or monitor is just about as easy as a microwave oven.

And NST would be the hardest to get.

Is a MOT really enough voltage to jump 1-1.5 inches?

 

[DashApple]

Is a MOT really enough voltage to jump 1-1.5 inches?

Not really no , 50Hz/60Hz MOTs sit at around 2Kv ,

 

[USAbro]

So than nospin, why are you recommending that big of a spark gap.

 

[Down with Umbrella]

And NST would be the hardest to get.

Careful with those mots. As it's been mentioned they can inflict a lethal shock.

If it really comes down to it I have three extra NSTs. Two 12k/30mA Franceformers. I haven't tested them out yet but I'd be willing to let you have one for nothing provided you paid for the shipping.

 

[Sigurthr]

The MOT output isn't enough to jump several inches, but a MOT powered TC when properly tuned and set up can provide up to about 1200Watts... enough for nearly three foot long hot arcs.

You can use MOTs for a static gap, you just need excellent forced air cooling and quenching of the gap. There is the phenomenon known as "power arcing" in high current air spark gaps where the electrodes get hot and give off enough electrons to keep the arc channel ionized, this acts as a resistor shorting out the tank circuit, doing nothing but eating tons of power and producing more heat. This is well documented in this thread pages and pages back, as well as the designs Speedy is using for his MOT powered spark gap tesla coil.

 

[Down with Umbrella]

Well I have some bad news regarding my TC. I set both my TF safety gap and main gap separately but when I connected the two and did a spark test I got nothing. But a bit of erratic spark gap arcing.
My connections seem solid(crimped 3/8 tubing with 6awg wire). Could be the alligator clips? Excess loops in the gto cable I haven't cut yet? Who knows..:/ seems like something to do with the terry filter.
Maybe some more testing tomorrow.

 

[nospin]

Sigurthr is right the gap needs to be close enough to start and then you
need high flow right at the arc point otherwise it never quenches to open the switch and just power arcs

most designs narrow down at the gap and then open back at the other side
but you need high temp mounting of the electrodes or enough flow to keep it cool

 

[Sigurthr]

Umbrella; it's time to remove excess components and nail down the problem; remove the safety gap, remove the terry filter. reassemble without them, and see how it goes.

 

[Down with Umbrella]

Here is two run and set up videos to see what I have going.
Variables, variables, variables. Here's a somewhat alarming part. I've thrown the switch 50 times and never recieved even a twitch. In the video you'll see an angry girlfriend who received a small "zip" as I held the iPad. This happened when the arc flashed over to the RF ground on the terry filter(not actually caught on video). How could she recieve a static shock when I have a designated RF ground for the TF and the transformers, PFC caps, and blower are connected to the house ground? Shock came from switch housing(also ground to the house mains)
I feel like a D*** because I assured her it was safe. It COULD be a coincidence because she was also wearing a sweater and slippers. But it happened when the arc flashed over to the ground. Hm.
I disconnected the PfC bleed resistors as Nospin recommend.

Next is this issue with the terry filter AFTER I shortened the main gap. Yes there is a silicon barrier some how it gets through. Even after all the solder pads are ground off. I'm thinking this might need to be totally rebuild.

The GTO wires are left long so I can test out each component. @ Sigurthr. I set each individual gap with just the transformers.
I have tried to maintain brass hardware large gauge wiring to handle the load.

Another strange thing is sometimes I have to toggle the switch on and off once or twice to get it to fire. I Attribute that to atmospheric conditions and electrode anomalies.

 

[Sigurthr]

You've got to fix those links, umbrella. when using the YT tags just put the hash-code part, not the URL part of the link.

Btw, she got shocked because what she touched was grounded. You see, the thing about RF is that it transmits power everywhere around the source, and anything in that near-field vicinity can become charged up to a potential if it is isolated from ground while the circuit is running. She was the object at a high voltage, not the switch housing. If you don't want to be shocked then you need to ground yourself too!