Joule Thief

[TheNOP]

...but during that lecture to the London EE's I quoted the words he used to introduce a demonstration of several examples of wires vibrating at high frequency which passed very small sparks evenly across the space between them through the open air. He even used a single strand in a way to glow with sparks.

corona discharges.

The point of my question was that perhaps this tiny sparking is occurring across the air around the toroid whose overlaying primary is creating the very high frequency. Perhaps when the secondary is so close to the toroid this is made a worse problem.

Hazens has not complained about this and his magwire has a thicker coating than the RS magwire, I believe.

Anyway, Dog812, I am only saying it may NOT be worse. It may actually be more successful, but in being more successful, it may have a sparking problem coming along unexpectedly.

i can't really say why some are experiencing problems making their toroid that way.
but i don't think corona discharges are at play with the jt.

it is known that mag fields have greater pressure inside then outside a coil.

if this can prouve it to all. 
Tesla is specific about that when he talk about his pancake coil.

[jeanna]

There is a distinction made by NT between low frequency (high voltage) coronal discharges and those of high frequency.

the difference and what that portion of his lecture was about, is that with high frequency and somewhere he includes 10k hz as high enough, the discharge is very even and produces not streamers and individually identifiable sparks, but what appears to the human eye as a steady smooth brightness. He admits this is because the frequency is faster than the human eye can percieve it, but the point he is making in his lecture is that at high frequency high voltage sparks look like a smooth light at ordinary pressures and of ordinary air.

(!)

He even admits that in cases of even higher frequency, the sparks are so short they are invisible... but then he shows that they are still there.

Anyway, Dog812, do not give up. You may have found something too problematic to use with your HH's. But it may be great for something else.

This is the reason everybody should be sharing about their joule thief trials, even if something isn't working as wanted.
We all benefit by the discussion.

thank you,

jeanna

[TheNOP]

@jeanna
corona discharges and spark gap discharges.

the first is high voltage and is not really affected by frequencies.

the other is, and can occure at relatively low voltage, a few hundred volts, depending of the gap size and the dielectric inbetween.

most enameled wire are rated for at least 7k volts, but there are lower grades too.

[jeanna]

..

depending of the gap size and the dielectric inbetween.

The gap size is very small on a closely wrapped secondary and the dielectric is air.

most enameled wire are rated for at least 7k volts, but there are lower grades too.

Maybe it is a language thing. Nevermind.

It is also very very easy to make a small scratch in the thin varnish esp on the green or red varnish from the 26 or 30 gauge available from RS. A scratch even if it doesn't go through could allow a tiny and invisible discharge that would confound dog's results.

It isn't as though he is doing something really different here. He is just putting the secondary inside the primary. I am explaining how it could be possible to have a worse looking result by reversing the secondary position to on the toroid. As xee2 explained this is commonly done, so should be fine.
I have 2 toroids like that. Only not all the time. Just when the wires are a little too close to something... or each other. I can't see what, but I cannot trust those toroids and don't use them for most tests. They should be MORE powerful, but they are less powerful.

jeanna

[dog812]

When i said i had my pot maxed out.. i meant it was at 0 ohms.. sorry to be confusing..
I just tried it with a 68 phm resistor and it works. So maybe the 1k is just too big.. Ill keep popping in different ohm resistors till i find the highest one that works..

The main reason i put the secondary under the primary is due to space.. and a lack of it.. I am limited to a certain size due to my application.

Also when someone said i want the wires to be in the same location? What does that mean exactly?