Tesla Coil Build Thread

[Sigurthr]

Lol, that could have been a nasty surprise! Any blown equipment?

 

[Fiddy]

yup, BBQ'd every power supply on that board.

 

[Speedy78]

My conical secondary for my Siguthr Coil and the 4" sphere topload. The coil still needs its endless count of polyurethane but my drive motor broke on my winding jig on the last turn. Also the first tested MOT at 2100V. Other one I have I can't seem to get more than 6V out with 5V in? No idea what going on but I haven't ruled out a damaged MOT yet.

 

[Sigurthr]

Hehe, I can't wait until you get that coil finished!

 

[Seoul_lasers]

Welcome to Straya

:wtf: :thinking:

422Vac.. how did you manage that ???

One mistake with that much juice... Wow...

Thanks for the post!

 

[DashApple]

2 shots from my 2.5"x2" 950 KHz SSTC .

IMG_0405 219 by TwirlyWhirly555, on Flickr

IMG_0405 632 by TwirlyWhirly555, on Flickr

 

[Fiddy]

My conical secondary for my Siguthr Coil and the 4" sphere topload. The coil still needs its endless count of polyurethane but my drive motor broke on my winding jig on the last turn. Also the first tested MOT at 2100V. Other one I have I can't seem to get more than 6V out with 5V in? No idea what going on but I haven't ruled out a damaged MOT yet.

Thats a mad mini coil

You've got the right wires on the input and outputs? i know there is a heater coil wound on the secondary too.

:wtf: :thinking:

422Vac.. how did you manage that ???

One mistake with that much juice... Wow...

Thanks for the post!

My co-worker did it in our switch room, usually we have red, blue, white for each phase, but this particular cable was blue, brown and black, he thought the black phase was the neutral when wiring a single phase distribution board!

It just fired power supply's for errrrrything

 

[Seoul_lasers]

Wow, regarding that secondary coil! Looks very good! Are you going
Dual MOT with voltage doubler with that ?
Do you have a pic of problematic transformer that only gave you 6v?
Sounds like you tapped the filament winding... Could be a broken ground ??

...
The 422v 3 phase is nasty stuff. I have seen arc flashes from fuse boxes
with overly high voltages in industrial settings before... Never pretty!
Very dangerous .
Anybody near the flash can suffer severe burns from vaporized copper or other
Metals.
As you've indicated you've lost some devices already from the
unfortunate mislabeling of wiring on 3 phase. Sucks! Good thing no arc flash or
Wiring fire in your wall!

 

[Speedy78]

It will be 4 MOTs and one for ballast and a RSG of some sort. On the damaged MOT I tapped the same wire that I did with the smaller one and then the iron core of the xfmr. Identical to how I set up the other and get 80 something V.

Here is the working MOT at a calculated 2100V. My primary is labeled 1 and 2. The heater should be B and C. I got my voltage (89V) between A and the core of the transformer.
The letters and numbers may be hard to read. They are small and red on the wires.


Here is the damaged MOT where I tested between the same locations.

 

[Sigurthr]

Just to note; I had Speedy use 5Vac from his variac for the tests, which is why the 2100v is calculated and why he read the 89V. Much safer this way.

 

[Seoul_lasers]

Just to note; I had Speedy use 5Vac from his variac for the tests, which is why the 2100v is calculated and why he read the 89V. Much safer this way.

No doubt...
it really does sounds like an internal arc across all the windings then in the secondary windings if he got that low a reading. That's fairly uncommon if this xmfr came from an oven. These xmfrs are built like tanks.
Actually disassembling oven for many years and not one xmfr was faulty than than one with a broken ground from rough handling.
One idea to test that problem transformer is to put ~210Vac across the secondary and read the primary voltage. All going well 10-11Vac should be present at the primary.

Actually ... Do you mind posting a side view with the faulty transformer so that I can see all A B C wires...

 

[Speedy78]

I tested the resistance of the windings. 1.2 on the primary of the functioning MOT ans 1.0 on the damaged one. Secondary for the functioning on was 164.6, for the damaged one was only 67.4. Could that indicate a short?

 

[Sigurthr]

It certainly could be shorted. Don't chuck it out though, you can use it for your ballasting MOT since the primary is still good.

S_L I always forget, do you short the secondary or remove it for the ballast mot? (I'd think that shorting it would cause the core to saturate faster thus reducing effective impedance, but as I don't know the state or scope of the shunts in a MOT I don't know if you want it to saturate or not.)

 

[Speedy78]

If the secondary is totally unusable even as a ballet I'm going to make a high current secondary out of 4ga and melt things.

 

[Speedy78]

Found some MOTs on ebay for 15$ a piece which is cheaper than I can find any used microwave and these are tested working with a warranty. I grabbed four of them and I have my already tested ballast MOT. The damaged MOT got cut up today and I replaced the secondary with 1 and a half turns of 4ga battery hookup wire. Who says high current cant be fun!

Sig any way to measure the current on this using the CT from the USSTCC coil and my DMM?

Ghetto rigged my secondary to an oven turntable motor at 3.5rpm. Has about 6 layers of poly on it now and still half a can to go!

 

[Sigurthr]

Sig any way to measure the current on this using the CT from the USSTCC coil and my DMM?

Yes and no. No is the better answer; you need a scope to do it right. IF the waveform was perfectly sinusoidal and you built a peak detector (and RC hold) circuit you could then calculate the RMS current by measuring the voltage put out by the CT when put across a precision resistor.