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Getting the ball rolling...

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Blitzorn

Sat May 30 2009, 02:56AM

Registered Member #2128 Joined: Thu May 21 2009, 03:17AM
Location: Seattle, Washington, USA
Posts: 58

Yeah, i wasn't planning on ramming the grounding rod down to the upper mantle, just deep enough for it to be a good solid connection. Would it help at all if i moistened the ground first? It's pretty dry right now and i read that dry soil is NOWHERE near as good.

As for filtering, i think i've got that covered too now, my dad had a whole bunch of filtering equipment in boxes in his garage. Already lugged it down and have it wired up.

I am currently setting up the transformers in parallel, and so far everything is going fine, the transformers both work just dandy.

My magnet wire also came today, and i plan to wind my secondary tonight or tomorrow. I don't have a jig to help with winding and i haven't really got time to make anything fancy - is there anything i can do to help prevent unwinding and keep things moving smoothly? Are there any very simple ways to slap together a winding jig?

Herr Zapp

Sat May 30 2009, 03:15AM

Registered Member #480 Joined: Thu Jul 06 2006, 07:08PM
Location: North America
Posts: 644

Blitzorn -

If at all possible, keep your ground-rod location soaking wet for the next few days. Moist soil provides a much lower impedance ground path than dry soil, and if the ground is really dry it will take days for the water to soak down 1-2'.

A quick-and-dirty winding jig can be made from a pair of plastic funnels, a length of 3/8" diameter all-thread steel rod, a few pieces of 2 X 4, some 3/8" nuts and fender washers, and a variable-speed electric drill.

Support your secondary coilform on the threaded rod, with a funnel stuck in each end. Use the nuts and fender washers to secure the funnels so they center the coilform on the rod. Nail a few pieces 2 X 4 together to form a cradle for the rod, and attach the drill chuck to one free end of the rod. You should add some pieces of 2 X 4 to support the drill so it is not just "hanging" from its chuck.

This setup requires 2 people to operate (unless you have a foot-switch to control the drill): one to wind the wire, the other to operate the drill switch & control its speed.

You'll probably also want to make a small cradle to support your spool of magnet wire horizontally so the spool can rotate as the wire is drawn off. If you just let the wire slip off the top of a stationary, vertical spool, it gets 1-turn "twist" with every turn. This is probably not a problem with as large as the #24AWG that you're using, but with smaller wire (<#30 AWG) it can cause a BIG problem with kinking.

Regards,
Herr Zapp

StevenCaton

Sat May 30 2009, 03:15AM

Registered Member #1845 Joined: Fri Dec 05 2008, 05:38AM
Location: California
Posts: 211

Would it help at all if i moistened the ground first? It's pretty dry right now and i read that dry soil is NOWHERE near as good.

Wet ground is better in general for a grounding rod, but wetting the ground is probably not going to help you drive your rod deeper. Usually a ground rod can be hit in several feet pretty easily and then Thump!!!, you hit hard pan and the rod just won't go any further.

Assuming you don't have a slow lathe or gearmotor, the simplest way for you to make a jig would probably be the following...

Get a threaded rod and put it through your coil form and tighten the coilform on its ends with two nuts. (probably nylock nuts to keep the threaded rod from trying to shift its way down the jig as it rotates)

Make a support structure out of 2x4's (or whatever) and cut out a hole at each end for the rod to rotate through.

Now for the motor. Well, since you don't have a motor, the only thing that comes to mind would be to make a handle on one end for some other person to turn. Leave a large piece of your threaded rod sticking out of your jig so you'll have room to put a handle there. Another thing that might work (assuming your threaded rod is 3/8'' thick or less) would be to use a power drill. Squeeze onto the rod with the drill's chuck and use it to rotate the coilform around. That should work.

I think you will be much better off constructing some sort of a jig. Making the jig might take 45 minutes, but it will save you more than 45 minutes during the winding process. Ive never seen anyone hand wind a secondary, and I imagine it would be horrible.

Blitzorn

Sat May 30 2009, 03:25AM

Registered Member #2128 Joined: Thu May 21 2009, 03:17AM
Location: Seattle, Washington, USA
Posts: 58

That is kind of how i am imagining it would be - slow, horrible, and mistake prone. I might give it a quick shot just to see how it goes but i doubt it'll work. More later.

I wouldn't be wetting the ground to get depth, i'd be wetting it for increased contact are and conductivity.

The transformers are now phased and ready to rock!

coillah

Sat May 30 2009, 09:30PM

Registered Member #1517 Joined: Wed Jun 04 2008, 06:55AM
Location: Chico CA
Posts: 304

Couple of 2 cents,

I was more than able to wind my secondary all by myself, with very little issue or trouble. I can link pics of my set up if you want.

It was pretty clever I think, basically I had what SteveC is describing. Two boards, with the coilform held inbetween with threaded rod and PVC endcaps. One end of the threaded rod fit right into my hand drill bit, so I just clamped down on that and set up another threaded rod to hold the wire for wrapping. Then I just sat there, gently sqeezed the drill trigger and held the wire firmly so it wrapped tightly. I put masking tape on my hand so the wire wouldnt burn me. It will be troublesome at first, but after about the 10th wind or so it should be pretty easy. Be sure to use plenty of tape, like you would save a giant paper you were writing for english class.

Also, once I had my technique down it only took around 15 mins to complete 11" with 24AWG. My topload actually proved to be more trouble than my secondary. Same with the primary...

With your power levels the need for a ground connection that good is overdoing it. I would spend more time on the coil, rather than trying to ensure the ground will have good contact. A copper rod in the ground will suffice. But if you have time, do it, just one less thing to blame I guess...

Blitzorn

Sun May 31 2009, 06:20AM

Registered Member #2128 Joined: Thu May 21 2009, 03:17AM
Location: Seattle, Washington, USA
Posts: 58

Made another hardware run today, as well as some major scavenging - i'm fairly certain i am now in posession of everything i need for the duration of the project.
The spark gap is nearing completion, the primary coil is finished, the capacitor is around half done. The NSTs, Variac, Line Filter, and RF ground are all in working order. I am assembling my jig for secondary winding, and putting the final touches on the spark gap. Tomorrow i should finish up just about everything else!

I'll probably have questions at some point, so stay tuned. Will post pics if i can get my hands on camera soon >.>

Herr Zapp

Sun May 31 2009, 05:49PM

Registered Member #480 Joined: Thu Jul 06 2006, 07:08PM
Location: North America
Posts: 644

Blitzorn -

How are you determining the capacitance value of your salt-water capacitors? You'll need to know the value of the entire bank of bottles fairly accurately to make sure that you fall within the "tuning range" of your primary.

The best option would be to use a digital multimeter with a capacitance function to directly measure the capacitor's value.

A second option would be to build Terry Fritz' "Tesla Coil Tuner", a simple (~10 parts) solid-state resonance detector that can be used to determine the resonant frequency of both the primary and secondary circuits. However, you may not have enough time to locate the required parts before your project's due-date.

A third option would be to use a design tool to estimate the capacitance value of each bottle, based on the dielectric constant of the glass and physical dimensions. One tool is the Java calculator on Bart Anderson's Classictesla.com, at:

(The dielectric constant of flint-glass is typically ~5.0 - 6.0.)

Regards,
Herr Zapp

Blitzorn

Sun May 31 2009, 07:23PM

Registered Member #2128 Joined: Thu May 21 2009, 03:17AM
Location: Seattle, Washington, USA
Posts: 58

I have a multimeter somewhere that i intend to use, but since i didn't know that during the design phase, i just made the whole system so that there is tons of room to tune up or down on the primary. It can accommodate easily for the bottles having the estimated minimum per unit (about 0.68nF) and up to the maximum anyone i found had achieved (around 0.95nF). Of course, having such a huge range makes tuning a bit, er, tedious, so that's where the multimeter comes in!

Herr Zapp

Sun May 31 2009, 07:37PM

Registered Member #480 Joined: Thu Jul 06 2006, 07:08PM
Location: North America
Posts: 644

Blitzorn -

And you're sure that the multimeter has a capacitance function?

Most low-end (and many mid-range) meters do not.

Regards,
Herr Zapp

Blitzorn

Sun May 31 2009, 10:52PM

Registered Member #2128 Joined: Thu May 21 2009, 03:17AM
Location: Seattle, Washington, USA
Posts: 58

I'm pretty darn sure, i can't check it at this second, but it's my dad's, and he is a.) a stickler for absolute quality, and b.) an electrical engineer. I'll find out this evening.

In other news, my winding jig is built and i'm a good ways into winding the secondary (5 out of 21 inches).

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