Can you use a microwave transformer fora small Tesla coil? / Tesla Coils / Forums

Forums

4hv.org :: Forums :: Tesla Coils

« Previous topic | Next topic »

Can you use a microwave transformer fora small Tesla coil?

1 2 next

Move Thread

LAN_403

CokeCanNinja

Tue Feb 22 2011, 11:31PM

Registered Member #3706 Joined: Mon Feb 21 2011, 04:17AM
Location:
Posts: 11

I'm starting to design my first Tesla coil (a spark gap design) and I was wondering if I could use a microwave transformer instead of a NST. The coil will only be ~1 foot high and doesn't need to that powerful, I just want to build a coil to do some tricks with. I can get a microwave for free and rip out the transformer, but for a NST I'd have to shell out at least ~$75.

Dr. ISOTOP

Wed Feb 23 2011, 03:01AM

Registered Member #2919 Joined: Fri Jun 11 2010, 06:30PM
Location: Cambridge, MA
Posts: 652

MOTs are dangerous, high current, and low voltage. They're usually used for big coils, and even then only with shenanigans like DC resonant charging.

teravolt

Wed Feb 23 2011, 04:32AM

Registered Member #195 Joined: Fri Feb 17 2006, 08:27PM
Location: Berkeley, ca.
Posts: 1111

hi CokeCanNinja the answer is yes but the spark gap has to be deigned for the low voltage of 2100 vac. another option is 2 microwave oven transformers out of phase for 4200vac. They have to be exactly the same so they share the power evenly. Building this won't be easy or straight forward. The Kind of capacitors you use will have to get are polypropylene or pulse types of capacitors. I have seen pictures of 4mot teslas with 5ft sparks. CokeCanNinja these types of transformers are not toys and can be lethal when not respected or any high voltage so be mindful of what you do before you do it

CokeCanNinja

Wed Feb 23 2011, 06:51PM

Registered Member #3706 Joined: Mon Feb 21 2011, 04:17AM
Location:
Posts: 11

Oh well, I just I'll just plunk down some cash for NST.

DerStrom8

Wed Feb 23 2011, 08:24PM

Registered Member #3704 Joined: Sun Feb 20 2011, 01:13PM
Location: Vermont, U.S.A.
Posts: 92

CokeCanNinja wrote ...

Oh well, I just I'll just plunk down some cash for NST.

Before you do that, perhaps you can ask a local neon sign shop for old NSTs? That's what I did several years ago, and they ended up having two that they just wanted to get rid of. I just got them for free. I'm not sure if you have a local neon sign shop, but if you do, it is worth giving it a try.
Good luck!
Der Strom

Arcstarter

Thu Feb 24 2011, 05:43AM

Registered Member #1225 Joined: Sat Jan 12 2008, 01:24AM
Location: Beaumont, Texas, USA
Posts: 2253

A single MOT can get decent sparks with a voltage quadrupler and a charging choke. I made this after reading about Steve Conner's single MOT sgtc

Use a higher capacitance tank cap and lower BPS for longer arcs.

teravolt

Sat Feb 26 2011, 04:39AM

Registered Member #195 Joined: Fri Feb 17 2006, 08:27PM
Location: Berkeley, ca.
Posts: 1111

mots are a better choice because they are cheaper and easier to to find and lighter. Do you have a ebay account and what is your budget like? neons will need caps of a higher voltage but the of the same type. When I started out I made some caps out of sheeted glass and aluminium foil with a mixture of oil and perifin for insulator bewean each sheet of glass. poly caps will offer waight reduction and no mess at about 2.5ea. the forum has lots of examples of things poeple have done. what do you have in mind.

Dr. Slack

Sat Feb 26 2011, 09:16AM

Registered Member #72 Joined: Thu Feb 09 2006, 08:29AM
Location: UK St. Albans
Posts: 1659

NST versus MOT?

For a first spark gap coil, NST every time.

It's a first coil, so keep it simple. Higher voltage means more tolerant spark gap design. A MOT's 2kV is right on the ragged edge of what's possible, very touchy gap control, changes fast with erosion, you have a lot more freedom north of 10kV.

You *can* multiply a single MOT up to the same sort of voltage, but then it's more complexity, and DC. It's possible in theory to get a fixed spark gap working with DC resonant charging, but it's much better, more reliable, safer with a rotary spark gap, which is yet more complexity. Once you've had a fair bit of ozone in your nostrils, then RSG with DC resonant makes a very controllable, powerful and satisfying spark coil, but not for a first.

You *can*use multiple MOTs to stay AC, but then it gets heavy real fast as you add more MOTs, they're not realy insulated for the voltage you're stacking them for, so you probably need to put them under oil. It's not the way to do it, first coil or not.

As an aside, if you get bitten by an NST's 30mA or 60mA, you'll probably live. Get bitten by a MOT's 1amp and you'll probably die.

aris

Fri Jul 05 2013, 06:27PM

Registered Member #2871 Joined: Sat May 22 2010, 06:50PM
Location:
Posts: 81

hey guys i need some help about 4 mot stuck for my power supply of a big tesla coil.I use as ballast a fifth mot but this drops my output voltage too much....What can i use to ballast the quad mot stuck?

HV Enthusiast

Fri Jul 05 2013, 07:10PM

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

MOTs are low voltage - usually about 2100-2400V. They are also not internally current limited, so they will require a ballast.

2.1kV-2.4kV is NOT good for a spark gap coil. Too much current in the tank circuit / spark gaps to be efficient.

Franceformer used to make really nice 4kV, 20mA NSTs which were perfect for table-top coils. Not sure if they are still available, but they were great!

1 2 next

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