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New small 4 inch sgtc.

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Arcstarter

Tue Dec 30 2008, 01:53AM

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

Starting a new coil, and hopefully this project will actually be finished.. Past ones i did not have the money for or something got in the way.

I have most of the stuff coming. I have 12 cde .15uf caps coming, 48 22uf 400vdc lytics, 1000 1kv 1amp 1n4007 diodes, and bleeders for the doubler lytics.

Thanks to Steve Conner for the schematic taken from his website.

I have picked my power MOT, because of size and physical condition, and ability to stay cool with load(not too long, but better than my others).

I am using MOTs for the charging reactor. I know they are rated for much less voltage than i will be putting them under, but i am sure they will take it just fine. I mean look at the tiny chokes Steve used. Not only that, the voltage they will be seeing is dc for the most part. That means there is no resistance, other than wire resistance because inductors of course offer no resistance to dc. I have also put the mot across 12kv 60ma for a few minutes, and nothing changed.

Tank cap will be 10 cde caps in series, for 15nf and 20kvdc. Sounds low, but Steve did it :P. They will each have there own 10meg bleeders.

Primary is undecided, and secondary is 4 inch diameter and 24inches of winding with 24 gauge. I already had the former and the wire(from the unfinished and ruined 6 inch coil). I have not wound yet, but i will soon. I got one of those things made for mounting toilets, and sanded it down so that it would fit snugly into the pipe to hold it. When i am done winding i will put PVC cement in it and hammer it back on.

I don't have much building material around here and i have no more money, so i made an incredibly simple and cheap winding jig. Basically i cut out 4 pieces of wood with a hole saw mounted on my drill. Two of them where about the size of the inner diameter, and 2 where somewhat bigger. I then screwed the small one and big one together, to make two separate disks. I then cut a whole in the middle big enough to fit a metal pipe in. After i put the pipe in, i put a screw in to keep the pipe and 'end caps' from moving. After that i got a 1 1/2 by 5 1/2 and nailed two upright supports into it to hold the metal pipe that the secondary form was mounted on. I don't have any gear motors or belts to turn it with, so i did something very ghetto. After the secondary was mounted onto the upright supports, i put a spade bit into the pipe and hammered the pipe flat so that it fit tightly around the spade bit. Now, i can put my little electric driver on the end of the spade bit to turn it!

While making the thing to hold the electric driver in place, the thing that held the blade onto the jigsaw flew off, which made the whole thing move because the blade of course was the only thing keeping the jigsaw from moving forward too fast. Well, i had the jigsaw on full speed, with it locked on full speed, and my right index finger went under it, and it got hit, and crushed up against the foot of the jigsaw. The fingernail is broken in half and it may be broken. I cannot move it, it is numb, and it still hurts. But it did not hurt very bad, and still doesn't hurt too bad, so it may not be broken.

Will add pics later when i feel like it.

EDIT: Perhaps an explaination to why i picked something so over-complicated when i can just use my 12kv 60ma nst? Sure.

Well, there are many reasons. First off, i like the sparks. The sparks are different because you use much lower tank capacitance than a calculator would suggest. Also, higher BPS than most coils.

Also, the bps can by changed to anything without decrease in performance due to firing at the wrong time, like in the middle of the sine wave, since it is DC.

You can increase or decrease power simply by changing bps.

And, since it is dc, you can use lower capacitance(which also means higher, bps as stated above)

Arcstarter

Wed Dec 31 2008, 07:00AM

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

I received the capacitors today, and they are so small! Never thought they where that much smaller than the .68uf 1600 volt. Anyway, i am currently (YAY puns!) mounting them to a small chopping board, which is somewhat bigger (more like two times) than needed for just ten caps, so i will put a safety cap for the caps on there.

I sanded the secondary former down for about 2-3 hours in all, and then dried it with my heat gun. I did this because the pipe was on the side of the street, and i am not taking any chances on it. I always do, and it ends badly.

Also i already coated the former with one coat of polyurethane and spun it for about 2 or 3 hours to make sure it was dry. The small electric driver i used was not made for continuous operation, and it was under some load because it was so cheaply and quickly made, but it lasted, even though it was warm.

Tomorrow i will start winding it, and right after winding i will put a coat of polyurethane because i always waited too long and both times they overlapped. I will try to put maybe 20 coats of polyurethane, as i want it to look glassy like Chris Hoopers. The diodes won't be here for maybe a week or two, so i can put 3 coats a day, letting it dry 4 hours in between, which in one week would be 21 coats. Perfect.

I forgot to mention, i bought two PC Boards from radioshack, each 4 1/2 by 6 5/16 inches. 2200 indexed holes each, so i will cut each into 4 evenly sized pieces for 8 pieces, 2 of which will have 7 lytics, 2 will have 14 lytics, 4 will have 12 of the diodes.

The boards with 7 caps will serve as the 3uf doubler cap, boards with 14 will be the 1.5uf caps, and the 4 boards will have 12 diodes each, for a value of 12kv, but "It will never see more than 6kV in service so there is a 100% safety margin." (taken straight from Steve Conner's site). Each capacitor will have a 220kohm bleeder/balancer resistor, which will be 2 watts(more than needed, but i can use them elsewhere where the wattage rating may be needed).

Pictures and a video will be posted into this reply as soon as they are taken and uploaded

Firefox

Wed Dec 31 2008, 08:01AM

Registered Member #1389 Joined: Thu Mar 13 2008, 12:50AM
Location: Pittsburgh, PA
Posts: 346

Nice start, Arcstarter. The prototyping board is great for keeping everything nice and neat, though sometimes you wouldn't know it looking at some of my protoboard circuits. Can't wait for pictures :D.

vasil

Wed Dec 31 2008, 09:39AM

Registered Member #229 Joined: Tue Feb 21 2006, 07:33PM
Location: Romania
Posts: 506

We want pics.

Myke

Wed Dec 31 2008, 10:04AM

Registered Member #540 Joined: Mon Feb 19 2007, 07:49PM
Location: MIT
Posts: 969

Sounds like a cool project. Can't wait to see pics.

If there is HV on one of those prototyping boards, you would probably want to remove some of the copper pads between the wires because an arc might form in the space between the pads.
Also, 220k seems a bit low for a bleeder/balancing resistor, right?

Tom540

Wed Dec 31 2008, 07:28PM

Banned on 3/17/2009.
Registered Member #487 Joined: Sun Jul 09 2006, 01:22AM
Location:
Posts: 617

I am always impressed with projects that are mostly built with what you have instead of buying every single thing new. It gives the project a whole new level of coolness for lack of a better word. Those cde caps are a pain to get and are expensive. Wouldnt it be great to be able to make something just as good from home, hehe?

Arcstarter

Thu Jan 01 2009, 02:55AM

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

Wouldnt it be great to be able to make something just as good from home

Hehe.

I started winding today. i currently need about 4 inches more on the former and i can coat. So the hardest part is almost over. Unfortunately, the bottom half looks horrible. The top half went better. The reason is that it was dark so i could not see the gaps. The gaps are small, but really piss me off.

You may be wondering why wind when it is dark? Well, i have till this weekend and then it has to get out of the unused bedroom. I have nowhere else to varnish.

At one point the wire wrapped itself around the threaded rod holding the spool, and i turned it on and it jerked. Surprisingly, the wire didn't break!

But it did cause the wire to become sorta zig-zagged.

Before winding the pipe was soo smooth and shiny. Wish i had someone to show.

Update: got some pics and a video.

That is a video of me sanding the former down on the jig. I sanded because it came from off the street. I also dried it off with a heat gun for about an hour, and cleaned with 125 PSI from air compressor.

The secondary former on the metal rod.

The jig without the screwdriver.

Finished ugly secondary.

Told you it wuz ugly.

Another update: I got the last two videos. Oh, and btw, the secondary doesn't look as bad as it did on that last pic, maybe it was the angle and just discoloration. Idk.

Me winding the coil.

Varnishing the crapcoil.

Bennem

Thu Jan 01 2009, 10:22AM

Registered Member #154 Joined: Sun Feb 12 2006, 04:28PM
Location: Westmidlands, UK
Posts: 260

Tom540 wrote ...

I am always impressed with projects that are mostly built with what you have instead of buying every single thing new. It gives the project a whole new level of coolness for lack of a better word.

I second that!
i have made my coils with nothing more than basic tools like small hack saw, drill, few assorted screw drivers, soldering iron and multimeter.
A scope i had to borrow a few times from work.
Although it took longer to make,
i had a more sense of acheivement of making everything from scratch and using a lot of
parts scavenged.

All the best with your project Arcstarter
keep the pics coming!

Mel

vasil

Thu Jan 01 2009, 09:00PM

Registered Member #229 Joined: Tue Feb 21 2006, 07:33PM
Location: Romania
Posts: 506

It is my oppinion too. In my first coiling days I was inspired by Greg Hunter site and his ability to use anything he had in his hands. Sometime I just use for coiling things with completely different usage, and this make me feel creative in some way.

Hazmatt_(The Underdog)

Thu Jan 01 2009, 11:46PM

Registered Member #135 Joined: Sat Feb 11 2006, 12:06AM
Location: Anywhere is fine
Posts: 1735

Now remember, as the temperature changes it WILL get loose, so you're going to have to sort of manually twist the wire tight on the coil form. You'll know what I'm talking about after you see a couple of turns trying to fall off the coil form from the middle. As the temperature changes you'll have about a foot of slack distributed along the form, so you'll have to twist the loose sections to tighten them up again.

If you have to do it for a prolonged time eg. big coil, you'll notice that it tightens up again, that's due to your own body heat warming it up. So put it outside after you spent a few hours on it and it'll all be loose again XD. But after a few go-arounds the coil will be tight on the former and you'll never have a problem with turns falling off the form.

To avoid having to tighten the secondary windings all together, wind the coil on a cold night. If you do it on a hot day the coil gets pretty ugly that same night, and its a real bummer.

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