Joule Thief

[xee2]

@ jeanna

Other than suggesting that you check reading with a battery, there is not much I can do to help you with the scope. Most scopes are calibrated in units of time and voltage, not frequency. You should try reading manual again.

[xee2]

@ jeanna

Perhaps you could try looking in the yellow pages for a ham radio store near you. Take the scope to the store and ask if there is anyone there that can help you understand how to use it.

[jeanna]

Hi everyone,

I think that what I have run into is what they used to call self-inductance.

Tesla solved the problem of self-inductance with his pancake coil.

For instance, I had a toroid with a primary that took up 1/5 the space around the ring. I had 42 volts using a secondary of only 8 turns. And I captured them in a cap, proof that they were there.  Then I added another 6 turns and filled all the open space of the toroid, and the volts went up to 52v. Too bad, I didn't bother with the cap.

Next I wound this back to its starting place with a total of 22 turns. The voltage now read 75volts But I DID check with a cap. It only filled to 4.3volts.   That was pretty hard to believe, but now, I think it was correct.

Finally, I did the MK1 thing sort of, and wound the wires really close together went up then down. The voltage on the scope said 73volts. I cought 49volts in the cap in about 10 seconds.

See, I was thinking the way MK1 was winding the wires so close together would make worse self-inductance, but now, I think he really discovered something special. At least for the toroid shape.  Thank you Mark!

jeanna

[jeanna]

@xee2,
I have an email address for an american help desk at velleman. I will ask there. Thanks.

jeanna

[Mk1]

@jeanna

Thank You ! very much for all your detailed research !

Mark

Edit : i think the cross winding help keep the coil pushing and pulling (not just pushing) and help to keep the wave integrity
giving a better charging and robust current.

Also , i don't know about adding current in the jt coil , but a positive feedback on the pickup coil works well , you need at least 2 pickup coils but 4 is better and a bridge of diode .

You rectify one pair and send the positive from the bridge into the second pair , then the negative on the bridge and the out of the coil and your coil output .