My first decent size Coil / Projects / Forums

Forums

4hv.org :: Forums :: Projects

« Previous topic | Next topic »

My first decent size Coil

Move Thread

LAN_403

Andyman

Tue Jul 08 2008, 07:42PM

Registered Member #1083 Joined: Mon Oct 29 2007, 06:16PM
Location: Upland, California
Posts: 256

Well, I finally decided to build a "real" coil. All my others have been mini thrown-together coils that barely functioned. I have a 4.5 inch coil that I had wound probably half a year ago that has just been sitting gathering dust. So I wound a primary for it and acquired some capacitors. Anyways, heres the setup.

Power: 9kV 60ma nst graciously donated by Dr. Spark.

Capacitor: Currently, (25) .56uF 1600V CDE caps all in series. I have some other caps that I will experiment with as well.

Primary: I'm temporarily using 10 awg insulated wire for the primary coil. The coil was a huge pain to wind, with all that wire going through the holes. I don't know how some people do it. I have copper tubing, but I'm afraid of running into similar problems and can't figure out the best way to make supports.

Secondary: 4.5 inch outer diameter gray electrical conduit. 956.4 turns of 24awg according to teslamap. I measured the inductance of the coil and played with different winding height values until teslamap came out with the correct inductance. Pic, with toroids attached:

Spark gap: I'm using a segmented copper pipe gap, with an adjustable gap in series for fine tuning of the spacing. The extra gap is quenched by a blower. If I recall correctly, in segmented gaps, if one gap quenches, then the rest do as well. In my configuration, I have the one gap dedicated to quenching and fine tuning.

Right now, I'm getting at most 19" strikes to a grounded target no matter how much tuning I do. According to teslamap, my transformer should be capable of 40" sparks. Any suggestions?

Arcstarter

Tue Jul 08 2008, 10:11PM

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

Andyman wrote ...

Right now, I'm getting at most 19" strikes to a grounded target no matter how much tuning I do. According to teslamap, my transformer should be capable of 40" sparks. Any suggestions?

A thicker primary will help quite alot. Also you could make a rsg and add a few inches of sparks. If you have bigger sparks at the time you turn it on and then the die down, you are not getting good quenching. I made a rsg with a 3000 rpm scooter motor and using a hole saw and cut out a piece of 5 ply wood. I then got 8 wood screws and screwed them in after making sure the where perfectly placed. I connected all of the screws together with some wire. I got a 2x2 piece of wood and drilled a hole and put a screw through it for a stationary electrode. Did the same for the other side. It works quite well, as you can see on the video of my cruddy 4 inch coil and it works like it should. I get no decrease in performance after 3 minutes of constant running.

Mike

Tue Jul 08 2008, 10:53PM

Registered Member #58 Joined: Thu Feb 09 2006, 05:40AM
Location: Tri-Cities, Washington, US
Posts: 317

first thing is go buy 1/4 copper pipe and make a new primary with it. its like 20$ for a 30ft roll

Andyman

Tue Jul 08 2008, 11:48PM

Registered Member #1083 Joined: Mon Oct 29 2007, 06:16PM
Location: Upland, California
Posts: 256

Ok thats what I thought. I have the 1/4 inch copper tubing (50 feet) and I just haven't gotten around to making the supports.
The coils about my size that have such long streamers mostly have static gaps that I have seen. I'm also afraid that the RSG will be too powerful and kill my nst. One thing I can NOT have happen. I already have two candidates for an rsg motor.

The one on the left is a 2500 rpm scooter motor. It says its rated for 14 amps at 24 VDC though, which is quite a bit for dc. The one on the right I got out of an old trashed evaporative cooler. It's a 1725 rpm 3 amp motor and HEAVY.
With my coil though, it actually seems to be worst when it first starts up.
A couple questions:
For NST power factor correction, is any capacitor better than none at all? Does the pfc capacitor improve spark length at all?
For the protection circuit: Does a LC circuit work as well as an RC circuit if the inductance is high enough?

Arcstarter

Wed Jul 09 2008, 12:07AM

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

Andyman wrote ...

I'm also afraid that the RSG will be too powerful and kill my nst. One thing I can NOT have happen. I already have two candidates for an rsg motor.

The one on the left is a 2500 rpm scooter motor. It says its rated for 14 amps at 24 VDC though, which is quite a bit for dc.

First of all, if the nst has a capacitor while using a rsg, it will not harm it. The capacitor basically filters out the spike. And the nst should have a safety gap which would neep it from killing the nst. Also, the motor that i use only uses about 3 amps when i run it. It is rated for 14 amps when under a large load.

teslacoolguy

Wed Jul 09 2008, 03:50AM

Registered Member #1107 Joined: Thu Nov 08 2007, 10:09PM
Location:
Posts: 792

WOW lol it looks like we are all using the same motor for our rsg's. Im uaing a 2500rpm 24v 14A motor also for my rsg on "Big Red".

Moderator(s): Chris Russell, Noelle, Alex, Tesladownunder, Dave Marshall, Dave Billington, Bjørn, Steve Conner, Wolfram, Kizmo, Mads Barnkob