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please help with my first coil

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LAN_403

Wed May 30 2007, 09:20AM

Registered Member #809 Joined: Wed May 30 2007, 08:59AM
Location: Melbourne, victoria
Posts: 114

i have finally decided to build a coil but have many questions. first would an ignition coil circuit drive a tesla coil?. would these caps be suitable for a MMC configuration? http://jaycar.com.au/productView.asp?ID=RC5380&CATID=51&keywords=&SPECIAL=&form=CAT&ProdCodeOnly=&Keyword1=&Keyword2=&pageNumber=&priceMin=&priceMax=&SUBCATID=856
if the ignition coil won't work i could try to get a nst.
And tesladownunder i love your site its very informative and nice to know other people in Australia (like me) are actually interested in this stuff.
thanks

EDY19

Wed May 30 2007, 09:30AM

Registered Member #105 Joined: Thu Feb 09 2006, 08:54PM
Location:
Posts: 408

Those capacitors may work, but for that price each, you really might as well try something that is proven- like the CD942 series, or the GE42 series. As for the ignition coil- if this is your first coil, I would say to get a NST- its one less thing to go wrong- less maintenence and troubleshooting if something fails

Good Luck!

Wed May 30 2007, 10:37AM

Registered Member #809 Joined: Wed May 30 2007, 08:59AM
Location: Melbourne, victoria
Posts: 114

ok, so i will go down to a neon sign place and see if i can get one free

or cheaply anyway. but as i said this is my first coil so i don't know what voltage/current nst i should get? any suggestions? is a 30 milliamp one dangerous/ lethal?

Wed May 30 2007, 10:40AM

Registered Member #809 Joined: Wed May 30 2007, 08:59AM
Location: Melbourne, victoria
Posts: 114

also i tried google and could not find any info on the caps? are they not made anymore?

Sulaiman

Wed May 30 2007, 10:43AM

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

Adding to the above;
Making an ignition coil power supply for a spark gap TC is feasible, you will find quite a few people have done it,
you should get between 20 and 50 watts depending on coil type and your design,
which is enough for a working TC, but not very exciting.

An oil burner ignition transformer (OBIT) is a good alternative to an NST, with a little less power, but easy to find.

Whether you use an NST or an OBIT, for a first sgtc you MUST use a safety gap, any two smooth metal electrodes will do. (NOT 'pointy' electrodes such as nails etc.)
Set the safety gap as wide as possible but so that it 'fires' with nothing else connected.
I have killed NST and OBIT by having too large a spark gap.

When obtaining an NST or OBIT make sure that it's NOT one of the newer electronic types, an old-fashioned heavy transformer type is required.

I have made an sgtc using ceramic capacitors like the ones you're considering, they are not very good (quite poor).
The 'doorknob' transmitter types are good, but so expensive that I agree you'd be better to use good foil/film polypropylene capacitors.
You could use bottle capacitors which are cheap, but you will not know their capacitance, which will make designing a 'tuned' TC quite difficult for a first-timer.

Good Luck, don't be shy to ask for help, and stay safe.

Coronafix

Wed May 30 2007, 12:58PM

Registered Member #160 Joined: Mon Feb 13 2006, 02:07AM
Location: Melbourne, Australia
Posts: 938

This is the best place to get good caps in Oz.

Here are the caps I use in my coil.

There is a bit of a wait for them though.
NST new is not cheap but worth it.

Wed May 30 2007, 09:06PM

Registered Member #809 Joined: Wed May 30 2007, 08:59AM
Location: Melbourne, victoria
Posts: 114

thanks for the link. i sort of knew a little bit about rs but didn't know they had that big a range. also which one of these did you use because the link just takes me to the homepage?. also was your tc a nst powered one?
thanks for all the help

GreySoul

Wed May 30 2007, 09:36PM

Registered Member #546 Joined: Fri Feb 23 2007, 11:43PM
Location: Albuquerque, NM
Posts: 239

kv wrote ...

any suggestions? is a 30 milliamp one dangerous/ lethal?

If you don't know the dangers of high voltage you should really start by reading this:

Classictesla's Tesla Coilers Safety page:

Sam's HV safety FAQ:

....

After reading those you should have a better idea of what you're gertting into as well as what you need in the way of an NST. In general if you're scrapping or scrounging you take what you can get. If you're paying, then bigger is better up to what you can afford.I use a 12kv/30ma NST for my stuff and it woks fine. I've intentionally grabbed one of the 6kv legs (center tapped NSTs are pretty common) and I can assure you that you don't want to do it, even if it doesn't kill you it's gonna sting.

For caps I too recommend the CDE 942 series of poly film caps. they seem indestructible, if only for a longer period of time than the ceramics are...

Good luck on your coil. Also, if you want to really protect your NST build a terry filter, it's not a big investment.

-Doug

Coronafix

Wed May 30 2007, 11:38PM

Registered Member #160 Joined: Mon Feb 13 2006, 02:07AM
Location: Melbourne, Australia
Posts: 938

Yeh sorry, RS does that, the page expires.
The part number is 940C30S47K
ER - Capacitor, Polypropylene Film, High dV/dt, 3000v, .047uf
I use a 15kV 60mA NST. New for about $170.
The caps, I used 3 strings of 8 giving 17.6nF total.

Thu May 31 2007, 03:19AM

Registered Member #809 Joined: Wed May 30 2007, 08:59AM
Location: Melbourne, victoria
Posts: 114

would this transformer work? http://cgi.ebay.com.au/15KV-Neon-sign-transformer-tesla_W0QQitemZ230136467055QQihZ013QQcategoryZ105780QQssPageNameZWDVWQQrdZ1QQcmdZViewItem
also would i need to change the cap configuration to work with this?

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