The air core can be wound and then formed into a circle, by forming or winding it onto a clear 3/4 inch hose with a wood plug at the ends where they join together.  You'd have an air-core toroid, and depending on the size, it also becomes an antenna, just like the small UHF circular antennas. I think that those are about 8 inches wide. But, It would look more like a TPU coil.

  I could see the Joule Lamp as being like a small Tesla Coil, with a thicker pancake coil at the bottom, which could be made with a 1/8" copper or shiny brass pipe that can be shaped tighter, or more open, even out at an angle, to help tune the circuit.  It would look cool too,  retro, yes. The Exciter Joule Lamp...

Quote from: lasersaber on June 15, 2012, 01:15:39 PM
I have tried that and it works great. That is how I made the coil in this video: http://www.youtube.com/watch?v=bkZKD7LHCzM

I have not given up on the air core coils yet. I have seen some very promising effects with them.

Thank you for all the great videos LS! I will endeavor to play 'catch up' with you guys and post results when I have some results to post. You guys are truly inspirational. Keep up the great reasearch!!
Happy experimenting,
PC

@Nick Z

That's a beautiful view of the beach.  I live on a lake but yours is bigger!

The Torroidal AirCore you describe is exactly what I was thinking except I may make the diameter of the tube a bit smaller (1/2").  I have done some research on Torroidal AirCores - the magnetic field is completely enclosed by the coil which is ideal.

I tried the Tesla like coil with pancake near the bottom.  That's great for really high voltage and low amps.  To light multiple LEDs at around 90-120 volts takes amps.  That's why I started modifying to what you see now.  I can get up to 40 watts.  The fertile ground is an Aircore with 7.5:1 turns, completely wound secondary and primary.  I have even double wound both secondary and primary with good results.  I also suspect a tightly concentrated field within the secondary is key.  To achieve that requires a small diameter coil, and long length.  Capacitance using heavy insulated primary helps and needs to be balanced to the overall resistance to make the circuit function at high performance levels.

Getting closer.

Quote from: Lynxsteam on June 16, 2012, 12:12:19 AM
Update: I couldn't go to bed without looking at this aircore some more. 

Brightness is really good on this one.  I tried a few other primary spots and brightness doesn't apparently change.  I know that is dangerous to go by eye.

With one Utilitech 7.5 watt bulb I can drop amps to .75 at 140 turns, .398 amps at 180 turns for a 7.5:1 ratio.  Now we are talking!

The only thing I can see that is substantially different from other aircores is that the diameter is small.  Maybe this concentrates the magnetic field more strongly.  I wonder if an even smaller diameter and longer length would be even better.  Perhaps making the aircore on a pliable tube and bending it into a circle.  Instead of the field lines having to go out the ends and circle back around the exterior, the field would just go back and forth within the coil.

So rather than go big in all dimensions perhaps going long is better.

GREAT ideas flowing here, also Nick and others! 

Now let me emphasize again how EASY it is to make QUANTITATIVE MEASUREMENTS so that we don't have to "go by the eyes" only.  Lynx noted correctly:

QuoteI tried a few other primary spots and brightness doesn't apparently change.  I know that is dangerous to go by eye.

Right.  So again a photo inside my "simple" light box... and it is fast and easy to build!  I realize we may be criticized for the low-cost measuring tool -- but I will defend this as a way to get REASONABLE numbers with which we can DETERMINE WHEN WE ARE MAKING IMPROVEMENTS. 

Look, its simply a box lined with aluminum foil, and a light (lux) meter at one end.  Simple.
And the lux meter was less than $14 bucks! 

Maybe your calibration is "rough", using bulbs with known LUMENS on the package and known wattage.  That's OK -- we don't have the budget of CERN!  But just having "RELATIVE NUMBERS" when you change something is a BIG help.

For example, running the "cranberry" air-core built by Lynx shown in the photo below, I find 4650 Lux with three bulbs when running at 12V @ 1.20 A (14.4W).  Then, when I insert a 9-mm diameter ferrite rod into the air-core, I get 3720 Lux running at 12V @ 0.74A (8.9W).

Did the Lumens/Watt Increase?  To answer that, I would need to do a calibration using bulbs with known LUMENS on the package and known wattage.  And I've done that. 

BUT== even without a calibration for lumens, I can tell whether my little ferrite rod did an IMPROVEMENT by answering -- did Lux/Watt increase?  The answer is yes:

air-core alone:  4650 Lux/14.4W = 320 Lux/W for my light-box.added Ferrite rod:  3720 Lux/8.9 W = 420 Lux/W -- a big improvement in efficacy!

You see?  just having the light box in the SAME condition while I make changes OUTSIDE (in the air-core or circuit, etc) -- I can tell when I'm making solid improvements in the light output, per watt.   I can even put a number on the improvement -- 420/320 is about a 30% improvement.  I think that's significant, and it gives me ideas of further things to try now that I have a way to measure when I'm making improvements in light output/Watt.

Don't worry about the criticisms that this is a crude instrument, compared to CERN!   We can make refinements in the measurement later; right now we need NUMBERS from measurements, something better than the EYE alone.

PS -- which will work better (in more light output per watt), the air-core TOROID or the Tesla-coil (resonance-coupling) approach?  I'd like to know!  Happy experimenting!

oops -- accidental double post argh...