Joule Thief

[jeanna]

@ jeanna

hmmm, did you try all combinations of pickup leads and diode direction? I think you must not have the best combination.

well,
there are 2 pick up leads so that is 2 directions
The diode can go forward or backward
If I reverse them the spikes go up instead of down.
I tried 2 ways for the diode. I did not switch the probe on the pickup leads, because I am pretty sure the spikes would go in the opposite direction in the same amount.

I did get the same value that you did when I used the leads by themselves.

jeanna
OK
I will reverse the probes...

edit
I did

In one direction of the diode the probes can hook up 2 ways
1 way is 4v-7v
other way is 12v
In the other way of the diode the probes can be connected in 2 ways
1 way is 12v
other way is
4v-7v
One of these shows the spikes going up the other down.
done.

[xee2]

@ jeanna

Disreguard my last post. I need to catch up on what you have done.

[jeanna]

Ahh,
OK I see
thank you,

jeanna

[xee2]

@ jeanna

Do you have another diode. I do not understand how you could only be getting a few volts while I am getting over a hundred. You see the voltage spikes on the scope, so the voltage seems to be coming out of the pickup coil. A bad diode is my first guess at the problem. However, a bad capacitor could also do this. So if changing the diode does not work, try changing the capacitor. But, if I am correctly reading what you have done, you have already changed the capacitor so that is why I suspect the diode.

Regarding spikes on scope, the frequency of the JT is not very stable. This causes the scope to not repeat the positions of the pulses each cycle and so you see the pulses moving around. At least that is my guess as to what is happening. Without a scope it is hard for me to check. And you are correct, I need the diode and capacitor to measure the peak voltage because I do not have a scope.

Just to be sure, you are measuring the voltage across the capacitor using the DC setting on your DMMM I hope.

A test you could do to check the voltage would be to put a neon bulb across the output of the pickup coil (without the diode and cap and voltmeter). If the neon lights you are getting over 100 volts out.

[jeanna]

Yes xee,
I do have another diode but this was a brand new one.
They don't like going into the breadboard. the legs are a bit too fat and the metal is very soft, so I find it troublesome to deal with them and switching them around, so if it is not necessary, I will just skip it. I think your question has been answered. If it has not been, and you need me to try another diode, I will.
I like using the scope. It is comforting to be able to see the difference the various changes make.

I started out with 1k ohm resistor at the base, and I could just watch it change as I turned the pot down. this really helps. I like it. I am a newbie and not used to the back door approaches you and others without a scope are accustomed to doing.

so, as I say, I will help with a new diode if this is for you, but it is not for me.
What I would like to do is make a 20 turn mk1 and see what that does. I have never watched a small mk pickup as it changes . I have only seen it when it fills the toroid. I think there may be good reason to have a partial secondary on the big toroid, and I am loking forward to doing that soon.

Thanks for starting this up today. I would not have been expecting to have the toroid be able to start up this 3055, and it is gratifying to have this part of it working as it should.

thanks,

jeanna