Beginner building first TC. Requesting advice. / Tesla Coils / Forums

Forums

4hv.org :: Forums :: Tesla Coils

« Previous topic | Next topic »

Beginner building first TC. Requesting advice.

previous 1 2

Move Thread

LAN_403

Daniel Uhrenholt

Sun Feb 26 2006, 11:35AM

Registered Member #125 Joined: Fri Feb 10 2006, 01:52PM
Location: Aalborg, Denmark
Posts: 155

The biggest problem with the dual MOT, is that the spark gap heats up quickly.
I have made a spark gap that works fantastic with 2 MOTs, I used copper bars on heatsinks as vasil mentioned.

Here is some pictures of it.

HV Enthusiast

Sun Feb 26 2006, 02:37PM

Registered Member #15 Joined: Thu Feb 02 2006, 01:11PM
Location:
Posts: 3068

Again, i think we need to remember that this guy is a beginner and will be building a first tesla coil. Making ballasts, complex spark gaps, etc... is not something i would make a beginner do.

My opinion is to forget the MOTs and go with a standard NST. Its much simpler, and safer as well.

Steve Conner

Sun Feb 26 2006, 03:38PM

Registered Member #30 Joined: Fri Feb 03 2006, 10:52AM
Location: Glasgow, Scotland
Posts: 6706

Yea, but it's more expensive unless you've got the NST already. (Dave marshall was selling a bunch of NSTs over in Sale And Trade, though, there might be some left)

I vote for the simplicity of vasil's twin MOT design. He uses a ballast to stop the MOTs putting out such extreme levels of current and power. As another poster said, if you have more than two MOTs, you can use one or two of the extra ones as ballast.

Mike

Sun Feb 26 2006, 04:47PM

Registered Member #58 Joined: Thu Feb 09 2006, 05:40AM
Location: Tri-Cities, Washington, US
Posts: 317

I strongly suggest you look over

site. He has a nice MOT schematic for variable output, it uses 4 MOT caps , which im sure you have, but make sure they are the same values. Also in it he says its been wired for 120vac, but i think he made a mistake since the primaries are in series, for 120vac they are usually in parallel. Schem here

Also as vasil pointed out, the saltwater caps have been proven to be very worthy of TC operation. As you can see from Greg's site.

As for the Spark Gap, you'll want a static sucker gap, probably a 3inch tee with an electrode on each end opposite eachother, and a vaccum motor attached to the top to extinguish the arc.

Also the toroid you can just use flex duct etc.
I think this would be a great TC for your first time, it would be easy, cheap, and give good output. And if anything gets broken from mistakes, it wont really matter since most of it was quite cheap to make or get.

JSpark311

Tue Feb 28 2006, 02:17AM

Registered Member #252 Joined: Sat Feb 25 2006, 07:21AM
Location:
Posts: 3

Y'all have given me alot to read over. I will do this as I am waiting for parts. Thank you so much! I will post back when I have something cool to show the thread.

---Josh

Christian Coilist

Tue Feb 28 2006, 09:37PM

Registered Member #269 Joined: Tue Feb 28 2006, 05:35PM
Location: Columbia, MO
Posts: 2

I am kinda tight on cash, and don't have a lot to spend on this new (hopefully) hobby. I do believe that I am going to attempt to build one of the salt water capacitors mentioned by Vasil. Although I don't drink, I live in the engineering dorm which is not too far from frat row... can't imagine I'll have much trouble acquiring bottles. Just need to purchase glue, plastic wrap (to cover bottles while they are stored in my closet), aluminum foil, and aquire some motor oil! Even used oil I think would be okay. Should be fun.

EDIT: Removed irrelevant material.

EEYORE

Wed Mar 01 2006, 04:32AM

Registered Member #99 Joined: Thu Feb 09 2006, 06:10PM
Location: florida, usa
Posts: 637

I know ima get bit in the arse

...Why not a SSTC?
Steves microsstc is so easy to get going...I got it working on my very first try...Its fun, and alot safer than a newbie "playing" with NST's and MOT's...Just a handful of parts, and your set.

Matt

Part Scavenger

Wed Mar 01 2006, 05:28AM

Registered Member #79 Joined: Thu Feb 09 2006, 11:35AM
Location: Arkansas
Posts: 673

Well, there were already so many conflicting opinions, I thought I might go ahead and add my own.

If you're building a SGTC, especially for the first time. I would not recommend voltage doublers or any the like. I prefer NO silicon in my SGTC's. I have successfully used doublers, but if you ask me, they're not worth the trouble.

I don't see a problem with using bottle caps provided they are well made. I don't know why everyone hates them so much. I've only blown one, and my 30 or so bottles only varied +/- .1nF I'll admit that MMC's are better, but they're expensive.

To know their value, just get a capacitance meter, which if you're in this hobby for very long, you're going to buy anyway. A good cheap meter is this one.

I love it and it's pretty accurate for 30 bucks (regular 40, on sale most of the time for 30, I've seen it for 20) It's on sale for 24 bucks right now. I highly recommend buying this thing.

The most frustrating time that I had with MOTs is the amount of current they produced. I simply could not get the spark gap to quench! At 4Kv, they will need alot of ballasting, not to say it won't work, I've seen more than one person do it.

If you do go the NST route, I found it disappointing and frustrating because I didn't know what I was doing and fried my NST. I was able to fix it, but it was never the same again. Here's how I killed it so maybe you won't do it: I didn't know about setting the spark gap and how it could affect my NST. When adjusting the SG on an NST based coil, ALWAYS start small and move the spark gap apart until performance peaks. I was doing the opposite, and so killed my (suspectedly fragile) NST. And personally, I don't worry about chokes on a one NST coil, but I would include a safety gap.

Make a neat setup. Think the positions of the components through, avoid crossing HV wires (I like to have a + and - side to my coils), and keep wires short.

Download WinTesla and TeslaCAD. Awesome tools, great for plugging around.

Kelvin science sells magnet wire in small quantities. They had the best price last I bought some, but it seems to have gone up? Look at goldmine electronics too, they had a good selection IIRC. Maybe some others have good distributors.

Something no one posted about MOC's is that they are the wrong type of capacitor and not only will they explode sometimes, they also will just die. They are not built for high frequency nor pulse applcations and can wear out almost instantly.

IGBT's and H-bridges are used in Solid State Tesla Coils, and Dual Resonant Solid State Tesla Coils. (SSTC's and DRSSTC's) These are completely different animals than SGTC's. The theory of the resonant transformer being driven at resonance or some factor thereof is the same, but the drivers are way different.

Oh, yeah. Please, Please, Please be careful with the MOTs. The guys here, back at the old fourm, told me my MOT setup didn't look very safe with jumpers and all. Anyway, I was too embarassed then to say anything, but I almost killed my self with it.

(Yeah, I know you guys were right

) Use a chicken stick(PVC'll do) when testing arcs.

Christian Coilist

Wed Mar 01 2006, 06:10AM

Registered Member #269 Joined: Tue Feb 28 2006, 05:35PM
Location: Columbia, MO
Posts: 2

Thanks for the post! The TeslaCAD seems pretty darn useful! My Craftsman multimeter will not measure capcitance, but I think my RA's multimeter will. I'll ask him very kindly.

- Greg

previous 1 2

Moderator(s): Chris Russell, Noelle, Alex, Tesladownunder, Dave Marshall, Dave Billington, Bjørn, Steve Conner, Wolfram, Kizmo, Mads Barnkob