AC from Joule Thief Secondary/pick-up

[xee2]

@ 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

For a while I was posting both the positive and negative outputs from the pickup coil. But I stopped because the negative output is so small. If you reverse the diode in one of my JT circuits you will get the negative peak voltage instead of the positive peak voltage. In all of my circuits using a pickup coil for the output, the negative peak is so small it is can not supply much power. The negative output is produced by the current generating the magnetic field and this has a slow rate of current change and therefore generates a small voltage in the pickup coil. When the transistor turns off there is a very rapid change in current and thus a large voltage is generated in the pickup coil. You should be able to see that on the scope in the DC mode with the center of the vertical axis set at ground. But, just because that is what I am getting does not mean everyone else will get the same thing.

NOTE: The polarity of the largest output can be reversed by reversing the leads from the pickup coil. I always call the largest output positive.

[xee2]

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?

The circuit forces only one tansistor to be on at a time and forces both positive and negative pulses to be equal.

[jeanna]

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.

Ah yes.

It took me a long time and it took a lot of patience from both of us (some of it was in a raft of pm's) to get me to understand what MK1 was doing. I do think it is brilliant.
The Canadian they speak is french. That helped me a lot. to know that an "a" means "one" sometimes but can also mean "at" because that is what it means in french. Anyway, I will try to help if you want me to.

Here, for a conceptual starters, try this:
the coil is wrapped over the toroid then through the center in the same way throughout. It begins at one spot and progresses to the left a number of turns then turns "progression" direction and goes back to where it started. Then it crosses over (*) the primary or a blank spot and continues on the other side up the same number of turns and again returns to the beginning spot.

* when it crosses over, you can pull out a few inches of wire as in a center tap.

Try it with 10 turns in each way and see what you get.

The "tuning" of the primary to the toroid is important, too, but even though MK1 insists it must be done in the beginning, I believe that as long as you are in the ballpark with a certain toroid, you can fine tune it later.

He disagrees with me on that point, and he may well be correct.

In a way, you could think of it as a center tapped secondary if you connect it that way.
But connect it from beginning to end for the most volts. Then fine tune it for most volts output.

So, xee, give it a try and see what you get.

I like the way Hazens1 makes the primary. It is a wee bit less powerful than the true bifilar, but not much and a very good way to start tuning a toroid, because it is so easy to alter it.

jeanna

[nueview]

I think i would tend to agree with MK1 about the tuning first allot of what tesla did was about power structuring or getting from a high cycle to a lower cycle power curve or as in using the harmonic to do work at another level or should i say from another level as the article you posted talked about only wanting odd harmonics and from a DC any frequency could be attained this would have been important in early radio without tubes.
the article also talks about producing a high stress upon the system so if you push and pull at appropriate times you would double the stress upon the circuit more stress more effect
Martin

[jeanna]

Hi everybody,

Here is a drawing of the 2 tier circuit in a different way.
I will probably need to change this some more, but I think it shows some of the interesting parts better than any previous drawings.
All of these figures are with a 10 ohm resistor at the battery. The fully charged AAA battery made the basic voltage (=voltage of basic JTC secondary) over 100 volts and I started to blow leds, so, I added the resistor.

The other oddment is the resolution of the scope.
For most figures the probe had to be on the x10 level because the voltage was off the chart otherwise.
But the scope sees more when it is "far away" at x10 than it does when it is at basic 1:1 probe strength.
I do not know how to resolve this.
So, this is what I have now. I hope you will find it interesting too.

jeanna

EDIT, in asking Bill to look at this I came across the description of "nested parallel circuits" I made that up of course, but I think it might help in figuring out what is going on here.