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Making my first coil, SGTC need help with powersupply.

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Estragon

Mon Aug 04 2008, 08:46AM

Registered Member #1391 Joined: Fri Mar 14 2008, 04:49PM
Location:
Posts: 40

Thanks for all this help! Well, so all my capacitors wont go to waste I wil connect them in series so they get even better voltage handling, or is that an overkill? Atleast i got some extras for repair and tuning :)
But then all I need to start building is my sommerjob to be over (so expect to hear a lot from me next week, if i start building :) ),
a good variable speed motor, and a RF-ground.

Could those fans in microwave ovens connected to a dimmer work? They spin pretty fast, but if I have to compansate for lower speed in the motor, can't I add more screws to the wood disk.

And would some "tent plugs" stuk down in the ground over an areal, and connected to each other serve as an uable RF ground, or would I need somthing better?
Or could i just hook it up to an roadsign or a streetlight? They look like big usable metal poles in the ground :D
Or.. could i use the ..mains ground.. ? Sounds kind of dangerous :P

Arcstarter

Mon Aug 04 2008, 08:43PM

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

I am not terribly sure, but i think the microwave fans would need a different frequency to have a different speed... I am not sure. You could just go to a store and by a motor that has a nut or screw on it for securing the disk for the rsg. Yes, you could add more electrodes for higher bps, but it has to be an even number and it has to be evenly spaced.

Estragon

Mon Aug 04 2008, 09:12PM

Registered Member #1391 Joined: Fri Mar 14 2008, 04:49PM
Location:
Posts: 40

Oh, okay, thanks!
So in the fans, voltage = torque, hertz = speed ?
It make sense, but I can just check with a dimmer later, to be sure. Or I just have to find a good motor somewhere.
But what about the RF-ground?

Ultra7

Mon Aug 04 2008, 09:21PM

Registered Member #1157 Joined: Thu Dec 06 2007, 12:11PM
Location: Houston, TX
Posts: 307

My RF ground is a 8 ft ground rod next to my garage.
But, If you don't have a spare ground rod lying about, you can sink 6 or 8 one foot sections of metal pipe into the ground and connect them all together with some flat braid ground buss wire for a nice segmented ground.

Either one you use, be sure to water it in about an hour before you run your coil.
I've found that the dry hot weather in Houston, TX makes my yard a very poor ground unless I wet it down before a run.

Lets have some pic's once you start building.

Estragon

Mon Aug 04 2008, 10:43PM

Registered Member #1391 Joined: Fri Mar 14 2008, 04:49PM
Location:
Posts: 40

Sure, I'll post pic's :)
But, I live in Norway, we got a LOT of wet ground xD

Metal pipes you say, is the surface areal of the ground very important?

Estragon

Thu Aug 07 2008, 09:30PM

Registered Member #1391 Joined: Fri Mar 14 2008, 04:49PM
Location:
Posts: 40

Now that I'm gonna start building I just want to make sure; Conical primary?

And another thing, how is the top of the secoundary usualy connected to the torroid?

Emmh, and could I use some glue/varnish like stuff I got to cover over the connections to supress corona?

Yeah.. :) And how many turns of primary you think I will find resonance at, like 5 or 20?

Aaaand, can the RF-ground and the strikerail be connected? Or must they be diffrent "grounds"?

quicksilver

Fri Aug 08 2008, 04:04PM

Registered Member #1408 Joined: Fri Mar 21 2008, 03:49PM
Location: Oracle, AZ
Posts: 679

ABSOLUTELY do not use the main ground for your radio frequency ground. I learned this the hard way. Keep them separated! In fact do what you can to make sure that the RF ground does not contact any portion of the mains or utility ground. - it is not only asking for tuning trouble but opens the door to real problems with ruining other more delicate items within the home, etc.

Actually I've seen a coil function fairly well that appeared not to possess a RF ground as I thought it would appear. Superficially the RF ground went no where; but I was told this was to isolate it. The coil still worked well. I would not recommend that drastic of a thing either but placing it within the mains grounding circuit is asking for problems you don't need.

The connection of the secondary to the toroid (IMO) should be as short as possible and direct. No extra wire; just clean and moving in a curving position with the rest of the coil to the toroid in a short a spiral as possible.

Estragon

Thu Aug 14 2008, 08:13PM

Registered Member #1391 Joined: Fri Mar 14 2008, 04:49PM
Location:
Posts: 40

Now I have started to construct it, but I would like your ratification before I power anything up.

I filled the capacitors with oil, that increased the capacitence to 5nF each, so I may use 4 with two of them in series, then parallel with the two others. To obtain a your recomanded value.

I could not wait, so I tested the powersuply. It makes WILDE arcs, loooong when I pull them out, and really hot, the copper wire melted at the tipp. Looked like it would be impossible to quench, but I am sure that will be diffrent, XD

The primary are just made of kinda thik stranded copper wire :( it was the best i could get, for my budget anyway :) !

The entire think is very cheapish and ugly, but I just want to try to make a first coil, upgrading is possible later :)

So, please. Is anything here wrong/bad shound anything be changed?

Arcstarter

Thu Aug 14 2008, 11:57PM

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

It is coming along very nicely! It looks like what i used but better because my 2nd tesla coil with 1 1/2 foot arcs used the same kind of primary :P. I think you will get some pretty good sparks with all of that after some tuning. Just dont forget you MUST use a rsg because using a static gap will not allow the capacitors to charge up and you will just get a hot arc across the gap.

Cannot wait to see some sparks hitting that strike ring!!

Estragon

Fri Aug 15 2008, 09:27AM

Registered Member #1391 Joined: Fri Mar 14 2008, 04:49PM
Location:
Posts: 40

Thanks you :) I would never have come this far without your help XD

But if the spark gap got problems quenching, could i use a static spark gap in series with the rotary? I saw that in one of the videos you linked, but first I should to check how it workd just with the RSG. Wich I have not made yet. Hmm, mot-fan with a triac dimmer is supposed to work.

Edit: BTW, the triac dimmer works with the fan-motor.

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