UK toroid source / Tesla Coils / Forums

Forums

4hv.org :: Forums :: Tesla Coils

« Previous topic | Next topic »

UK toroid source

1 2 next

Move Thread

LAN_403

Stuart G.

Tue May 31 2011, 12:25PM

Registered Member #495 Joined: Thu Nov 09 2006, 01:29PM
Location:
Posts: 11

Hi

I've been looking for a spun toroid to use as the topload for a Tesla Coil.

So far all the places I have found have been based in the united states.

I was woundering if there are any UK based places where I could purchase a torroid or have one constructed for a reasonable price.

So, anyone know of a place or a guy who can make/sell these?

uitvinderalex

Tue May 31 2011, 01:29PM

Registered Member #3662 Joined: Wed Feb 02 2011, 07:20AM
Location: Netherlands, Steyl
Posts: 4

I had the same problem here in the Netherlands, so I decided to make my own toriod. I bought four aluminium 90 degrees elbows and welded them together. After that I sanded and polished it to a smooth surface. The total cost of material was about 200 euros. You can find a picture of the result here:

So if I were you, I would search for a company or person in the metallurgy and asks them if they're able to make it and asks for a quatation, I will take a lot of hours to build one.

Ash Small

Tue May 31 2011, 02:03PM

Registered Member #3414 Joined: Sun Nov 14 2010, 05:05PM
Location: UK
Posts: 4245

The link above doesn't work, but you can copy and paste into google and get there

Sulaiman

Tue May 31 2011, 06:13PM

Registered Member #162 Joined: Mon Feb 13 2006, 10:25AM
Location: United Kingdom
Posts: 3140

On the assumption that this is your first TC;
- make your own .. very easy just not pretty.

I like aluminium ducting, e.g.

I used an old bicycle wheel to hold the ducting as a ring.

don't spend too much time/money on your first TC
as you will almost certainly want to make a second version after learning from the first.

Stuart G.

Wed Jun 01 2011, 02:09PM

Registered Member #495 Joined: Thu Nov 09 2006, 01:29PM
Location:
Posts: 11

I'm actually at university, the university of strathclyde to be more specific

I built this sstc as part of a fourth year project

Tesla

It's based on Steve Corners PLL work

I can get a few cm of partial discharge by using pointed electrodes and placing a ground electrode nearby. I can get a plasma arc to form over a gap of about 5-10cm. I was thinking that some of my problems might be due to the large diameter of the electrode, hence my search for a toroid.

I'm currently being employed by the university to upgrade the tesla coil I built as my forth year project, and there is budget available.

To achieve some partial discharge as opposed to plasma arcs, I was thinking toroid electrode, smaller air gap between primary and secondary aswell as possibly going to drsstc operation, currently its working of a 300V DC supply.

Discharge photograph

Should I start a new thread asking for general advice or keep posting in this thread?

Ash Small

Wed Jun 01 2011, 02:36PM

Registered Member #3414 Joined: Sun Nov 14 2010, 05:05PM
Location: UK
Posts: 4245

I think you can change the title of this thread by using the 'edit' function in your first post.

I've not done this myself, but others have changed the title of their threads.

There was a recent discussion on topload ideas here:

including some advice on using 90 degree cast aluminium bends.

Steve Conner

Wed Jun 01 2011, 08:11PM

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

Cool! I went to Strathclyde uni, it's nice to hear that my PLL driver found its way home.

Whenever I've wanted small or medium-sized spun toroids, I've had to buy them from John Freau in the USA. He takes Paypal and always seemed happy to ship them to the UK.

What frequency is your coil running at, and how many turns does it have? It looks like it's making plenty of current but not enough voltage.

Stuart G.

Wed Jun 01 2011, 09:56PM

Registered Member #495 Joined: Thu Nov 09 2006, 01:29PM
Location:
Posts: 11

secondary resonant frequency is 230khz with the spherical electrode

The primary is 6 turns, tightly wound

Secondary is 600 turns

Am I right in thinking that reducing the air gap between primary and secondary will increase the coupling and therefore the power transfer.

The system is currently drawing 5A at 300V and the steel electrodes are melting at the tips

PS, I think we might have met steve, I seem to remember seeing you and your coil at strathclyde during a open day four/five years ago, wanted to build a tesla coil ever since

Steve Conner

Thu Jun 02 2011, 06:12AM

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

OK, so I could be wrong, but I think it needs more turns of thinner wire to get the output voltage up. Either that or something is wrong with the driver and it's not driving at the actual resonant frequency.

The air gap between primary and secondary should be as small as possible, the coupling literally can't be tight enough. What limits it is flashovers. There is a high voltage between primary and secondary, and if the gap is too small it breaks down and your coil goes on fire. Yours seems reasonable.

Does it draw that high current even when you're not arcing it to ground?

Stuart G.

Thu Jun 02 2011, 07:09AM

Registered Member #495 Joined: Thu Nov 09 2006, 01:29PM
Location:
Posts: 11

It draws approximately 1A when not arcing to ground and 5A when arcing to ground, thats also the limit of The PSU I'm using

The pll naturally outputs 250Khz and drops to 230Khz when the Tesla coil is powered up, so I believe that is the resonant frequency

Can you explain how the audio modulation works on your PLL diagram, does providing a voltage input there detune the oscillator?

1 2 next

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