AC from Joule Thief Secondary/pick-up

[Pirate88179]

Actually, from my small experience with my scope, as well as looking at other JT scope shots, my regular JT's (with no secondary) put out AC as well.  It may very well be pulsed DC but there is for sure an AC component to this, just like the earth battery.

Bill

[nueview]

Hi all
i see Xee2 got it figured out i could not get my picture to post but i am not real computer savy.
but he is right about a good sign wave with this circuit i used darlington transistors as they switched power faster in more bulk but this would be hard to do at low voltage.
Martin

[jeanna]

@xee,
@nueview,
I think I understand what you are suggesting??

Are you suggesting the second transistor will do what the second set of sparks produce in the drawing?

It might.
I was thinking along those lines when I put together the 2 tier, and found that the transistor was not being used.

The thing about adding another transistor is that it would be very easy for one to cancel out the other. Wouldn't there be a way to use the pulses as they are and they are fairly high in many jt circuits, and then just make more separate secondaries that work off the pulses?

just thinking,

jeanna

[TheNOP]

a dual transistor circuit is not really required to get AC at the pickup coil.
starting with 3 volt instead of 1.5 would surely help tho.

what is needed to get AC is rise and fall of the current over a time period.

on the pickup there are no reference to a "zero" voltage point.
you could make one with a center tapped coils.
the AC voltage could be biased relatively to an other circuit or earth point it does bot matter it still would have 2 polarities, high and low.
in AC form you can view them as + and -, but only to a reference point.

what a cap is storing is a potential difference.

[xee2]

Have you ever tried to make a MK1 type pick up yourself?

No. I do not understand most of what Mk1 is saying. I also do not understand most of what ist is saying. I think maybe I just do not understand the Canadian language. They seem to have learned some kind of electronics that I do not know anything about.