Joule Thief

[jadaro2600]

Now I'm confused: do we need high permeability or low permeability?

[jeanna]

Now I'm confused: do we need high permeability or low permeability?

RIGHT!

I just checked for resistance of the toroid material because someone said this predicts the permeability. (I think my brain is high permeability! There are so many contradictory things.  )

I have 4 that are not painted - well maybe 3. One looks like cement, but it may be paint.

the highest permeability according to the vendor has a resistance of 12Kohm from inside to outside the material.
EDIT btw this gave me the hands down worst results (except for the one I mentioned last night.

I have OK results using the medium toroid from goldmine 5/$1. This one says 3Kohm

The 2 best ones are the little charcoal from allelectronics which is definitely not painted and it is >2Mohm off the chart
and the 'filter' from goldmine which may be painted and is also >2Mohm.off the chart.

the charcoal is too small for many turns of secondary so it is limited.
This 'filter' gives me my best results.

Is it OK to remove the paint from these things? anyone know?

Thanks jadaro. good question.

@MK1

I missed if you ever tried different lengths on your MK's?? ??

EDIT ADD:

I got higher results from the secondary on my MK1 in January. 30v and 29v. But these were from 52 turns up down up down and 7T bifilar split primary. I think you are right it must be the toroid. but with 25 turns = 20 volts each way rectified from 1.2vbat on each of 4 wires from the same core with room for more is not discouraging at all.

thank you,

jeanna

[jadaro2600]

I got some toroids from the same place and they're giving me crap - I'm having better results with these Helmholtz style inductors that I posted a while back.

I mean, these toroids are absolutely giving me crap results.

*edit:  I put a coin in between the two Helmholtz style inductors, and the circuit will stop functioning.  It's interesting that these two aren't physically sharing a core, yet they work all the same and produce ~120v.

[Mk1]

I got some toroids from the same place and they're giving me crap - I'm having better results with these Helmholtz style inductors that I posted a while back.

I mean, these toroids are absolutely giving me crap results.

Sorry i don't see it that way .

Mark

[jeanna]

Jadaro,
Did you ever get 20 or 30 rectified volts from the secondary on your helmholz coils?

jeanna