What is the most accurate way to calculate length of pipe for secondary? / Tesla Coils / Forums

Forums

4hv.org :: Forums :: Tesla Coils

« Previous topic | Next topic »

What is the most accurate way to calculate length of pipe for secondary?

Move Thread

LAN_403

nzoomed

Thu Mar 26 2015, 10:29PM

Registered Member #54503 Joined: Sun Feb 22 2015, 10:35PM
Location: New Zealand
Posts: 288

Im questioning how accurate wintesla is in working out the given length of a secondary for any given number of turns, diameter of pipe and wire gauge.

This is mainly due to my figures giving me a far greater number of turns than what other people have made on the same size coil.
I am wanting to cut my pipe to length and dont want to find ive cut it too short when winding.

Is there any other programs that i can use as a guide?

TIA

dexter

Thu Mar 26 2015, 10:43PM

Registered Member #42796 Joined: Mon Jan 13 2014, 06:34PM
Location:
Posts: 195

if you are confident on winding as tight as possible regardless if is on a small form or on a big pipe do this trick to find out the secondary length:
wind a 100 turn control coil on a small form measure its length and use this data to approximate for bigger coils - it worked for me quite well so far

nzoomed

Fri Mar 27 2015, 12:59AM

Registered Member #54503 Joined: Sun Feb 22 2015, 10:35PM
Location: New Zealand
Posts: 288

dexter wrote ...

if you are confident on winding as tight as possible regardless if is on a small form or on a big pipe do this trick to find out the secondary length:
wind a 100 turn control coil on a small form measure its length and use this data to approximate for bigger coils - it worked for me quite well so far

OK, that sounds like a good idea, i think the software is not too far off anyway, i just discovered that SWG wire was being used and that was enough to put the resutls out by quite a bit!

Mads Barnkob

Fri Mar 27 2015, 07:14AM

Registered Member #1403 Joined: Tue Mar 18 2008, 06:05PM
Location: Denmark, Odense C
Posts: 1968

I use the simple helical coil calculator here:

and use the numbers to plot into JAVATC:

Rule of thumb is that the varnish on the wire is about 10% of the wire width, so that is your spacing.

nzoomed

Fri Mar 27 2015, 07:37AM

Registered Member #54503 Joined: Sun Feb 22 2015, 10:35PM
Location: New Zealand
Posts: 288

Mads Barnkob wrote ...

I use the simple helical coil calculator here:

and use the numbers to plot into JAVATC:

Rule of thumb is that the varnish on the wire is about 10% of the wire width, so that is your spacing.

That was helpful thanks. It must be correct, that calculator only has a 7m difference than what wintesla was giving me, which is nothing considering we are talking about 1300m of wire!

Signification

Fri Mar 27 2015, 05:03PM

Registered Member #54278 Joined: Sat Jan 17 2015, 04:42AM
Location: Amite, La.
Posts: 367

In the 90's my Tesla coil interests peaked. After a couple of years working with them, I found better ways of making, mainly, secondary components. One was to make a toroid that wouldn't sag over time (a BIG problem). a 50 pounder has been siting for 16 years without a mm of sag! NOW to the main topic of secondary windings...although this is not mainly dimension calculations, I thought it may be helpful. I had never been able to match thin acrylic tubing with fairly thick-walled PVC until I decided to go all-out for a method of winding secondarys. I built a special coilwinder for large (length / diameter) coils. Here is how I wound secondarys which gave me performance far beyond my expectations. I built a "drying box" heated with, at the bottom under hardware cloth, an array of incandescent light bulbs controlled by a variac. The top had five 3/4" inch holes drilled in it and stopped with corks. One cork had a center hole through which one of those old "taffy maker" thermometers could be inserted to monitor temp. Briefly, I would cut the PVC to length, thoroughly wash it (I put the shorter ones through a steaming dishwasher cycle) I then placed it in the drying box, sometimes for a week, to drive out any and all moisture. Afterward, while it was still hot, I removed it from the drying box (with latex gloves) and put a quick somewhat thick layer of oil-based polyurethane on the inside of the PVC, installed precut and cleaned acrylic circular covers then quickly glued and inserted it into the coilwinder (which only made contact with the end caps). I kept it rotating so the inner poly would dry with a uniform surface thickness inside (no collecting on the bottom). Then (while still warm) I coated the outside with a thick layer such that I finally got a uniform thickness. After the coating process, I had a coilform effectively of oil-based polyurethane. When dried, I wound the coil with the proper guage magnet wire, with a constant tension, continuously wetting with poly. When finished, I put a final thick-ish outer layer of poly. When all was dry, I removed it and had a virtually uniform (reflected light revealed uniform straightness along the length) coil that was electrically a suspended coil inclosed within the polyurethane. These coils, by far, outperformed any standard PVC-core coils. The setup made it so easy, I actually wound one just for the fun of it!
I hope this is not outdated information and is useful to some readers.

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