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Help me debug my coil!!!

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Crimson Rain

Mon Oct 20 2008, 10:12PM

Registered Member #1745 Joined: Wed Oct 08 2008, 12:29AM
Location: Northen Michigan, US
Posts: 19

So I made a sgtc, had it up and running last week, then thought I blew my transformer. So I ordered a new transformer, and made a safety gap since im too cheap to get a terry filter, and Im still waiting on the transformer. For kicks and giggles I decide to just try out the spark gap with my old transformer, and lo and behold it works. I was very excited, and hooked everything back up together to start tinkering again. But when I hit the switch, NOTHING. I try disassmbling and reassembling different components to try and narrow down what could be the problem. Turns out, its the primary. What could possible be wrong with it? I hooked it up in parallel with the spark gap, and it wont spark, so I know this is the problem. The primary design btw is 1/4" copper tubing spaced at 1/4" with a 45 degree angle, 12 turns. Thanks for any help!!!

Bob J

Mon Oct 20 2008, 11:17PM

Registered Member #810 Joined: Wed May 30 2007, 05:23PM
Location: Quincy MA
Posts: 17

Hi Chrimson,
If you could link up pictures it would really help us understand your configuration........

Assume you get an arc from each terminal of the NST... If so, that's not a problem.... Since you had the system up and running last week and nothing else has changed you must have an open in your primary circuit.... Most likely candidates in my book are the tank caps (blown or a related connection).... Are you running a MMC?

Hope this helps...

Bob J

Crimson Rain

Mon Oct 20 2008, 11:27PM

Registered Member #1745 Joined: Wed Oct 08 2008, 12:29AM
Location: Northen Michigan, US
Posts: 19

Bob J wrote ...

Hi Chrimson,
If you could link up pictures it would really help us understand your configuration........

Assume you get an arc from each terminal of the NST... If so, that's not a problem.... Since you had the system up and running last week and nothing else has changed you must have an open in your primary circuit.... Most likely candidates in my book are the tank caps (blown or a related connection).... Are you running a MMC?

Hope this helps...

Bob J

Thanks for the reply. And as to your questions, I am unable to uplaod any decent pics, I dont have a camera

And as to the caps being blown or a related connection, I ran the system with the cap bank in parallel (took out the primary) to see if the spark appears normal (bright white light, loud as hell lol), which has me thinking its the primary. Does the primary need to be coated in anything to help prevents tarnish/corrosion? Ive noticed it looking pretty dull

Bob J

Tue Oct 21 2008, 01:01AM

Registered Member #810 Joined: Wed May 30 2007, 05:23PM
Location: Quincy MA
Posts: 17

Hi Crimson,

Sounds right for the caps....;- )

Might be your tap..... If you have an ohmmeter you can check out the connection.... Basically would trace the entire circuit looking for an open in one of the connections....

How is your spark gap? That's about the only other thing I can think of.... I would trace the entire circuit and look for an open...

Let me know if this helps....

Bob J

Dr. Drone

Tue Oct 21 2008, 01:19AM

Registered Member #290 Joined: Mon Mar 06 2006, 08:24PM
Location:
Posts: 1673

What type of NST? Does it have ground fault?

rgs,
ch

Crimson Rain

Tue Oct 21 2008, 03:07AM

Registered Member #1745 Joined: Wed Oct 08 2008, 12:29AM
Location: Northen Michigan, US
Posts: 19

Everything works, its just once you put the primary into the equation it doesnt. Like ive said, the spark gap by itself works, the spark gap with the cap bank works, but theres something wrong with the primary iteslf! I took a lead from one of the terminals on the transformer and connected it to the primary, then ran another lead from the primary to the spark gap (with a lead from the other transformer terminal to the spark gap obviously), and nothing. Thats how i deduced that its the primary in question.

J. Aaron Holmes

Tue Oct 21 2008, 04:26AM

Registered Member #477 Joined: Tue Jun 20 2006, 11:51PM
Location: Seattle, WA
Posts: 546

Hi, Crimson Rain:

It sounds like you may just be miswiring things. Are you sure you aren't accidentally connecting the primary coil directly across the transformer HV terminals? This would essentially short the transformer out, of course, so there wouldn't be anything to charge the cap or jump the gap. About half way down the following Wikipedia article are the two common Tesla coil schematics: http://en.wikipedia.org/wiki/Tesla_coil

Which did you use? The top schematic is preferred; placing the gap--not the cap--across the transformer keeps a lot of nasty RF voltages from hitting the transformer.

I would also add that running your transformer with just the gap and cap connected is bad. Without the inductance of the primary coil to limit the current of the cap's discharge, the cap may be damaged. And if you hook up the primary, make sure the secondary is there too. You want to get the energy out of the primary circuit quickly in a spark gap coil. If you don't, you're just burning up your spark gap and subjecting your cap (and possibly transformer) to excessive RF voltages and currents.

Cheers,
Aaron, N7OE

Crimson Rain

Tue Oct 21 2008, 05:36AM

Registered Member #1745 Joined: Wed Oct 08 2008, 12:29AM
Location: Northen Michigan, US
Posts: 19

OMG Im an idiot... I was drawing up a representation of my coil so you all could understand how I had my coil setup... The whole time I had the primary in parallel with the cap bank instead of in series with it. Sorry for all this fuss!!!!! *facepalm*

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