Joule Thief

[electricme]

@Jeanna,

spikes skinny and infrequent. There is no resolution that changes that. To me that means they are skinny spikes period.
159v, 77v,17v,5v, 151v, 25v, 38v, 25v, 20v, 161v, 167v.

no diode across secondary 
234v, 77v, 161v.

then I also removed the 100pF cap and it got still more spikes (but not much more) the lowest numbers dropped off again.

234v, 231v, 160v, 115v, 154v, 218v, 160v.

really ugly.
jeanna

What you are seeing is the circuit is "hunting" or "cycling".

I begins to build up then all of a sudden it carnt keep the pressure up so it collapses and then it sees, headroom, and so it tries again and again and again.

Try adding another 1.5 batt in parallel with the original bat and see if it is current related, if it stops hunting then its current related.
If that is the case, look for something taking more current from the circuit.

jim

[jeanna]

Jim, maybe this is true, but without a scope from MK1 or xee, or anybody else for that matter, it is impossible to know if this is normal or strange.
I see it all the time when the scope is across the secondary. If I collect it in a cap, it is the top value that the scope sees.

Here is my response diagram to xee, just for clarity since all the parts are the same  but the way I did it is shown.

hmm, I should have kept that font bigger, sorry.

jeanna

edit here is the original design as copied by me. also

[electricme]

@Jeanna,
Its clear as mud     

Jim, maybe this is true, but without a scope from MK1 or xee, or anybody else for that matter, it is impossible to know if this is normal or strange.
I see it all the time when the scope is across the secondary. If I collect it in a cap, it is the top value that the scope sees.

Here is my response diagram to xee, just for clarity since all the parts are the same  but the way I did it is shown.

hmm, I should have kept that font bigger, sorry.

jeanna

Take a loko at the way the HV diode is connected.
The diode function as you know is to rectify ac, so allowing pulses of DC to get through.
By putting the diode "accros" the output, at every half cycle the half pulse is shorted out, allowing the oppersate half pulse to pass by to the rest of the output.

As an experiment, put a 5K pot with a LED in line with the HV Diode, then turn the pot as the JT is running, you will see the LED flashing (if low pulse freq) but you scope should show it.

jim
   

[xee2]

@ jeanna

hmm, I should have kept that font bigger, sorry.

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

[jeanna]

Jim,
I just added in the original style of the circuit that xee posted as copied by me.

I see a great improvement in the thing without any diode or cap in either place. (the mistaken place or the correct place)

If I were to run this through a full bridge and collect it in a cap I'd get the 235v that xee gets. I can see it right there in the scope. Just not very often.
The number of big gaps in the wave predominates, and so I doubt it is worth much. I could be wrong, but it looks better when there are spikes the same height and more of them which is what I see without either diode or cap.

But xee cannot do this without the diode and cap because it is how he makes measurements. Tooo bad. (but it is also how I can help. I can describe to him what he cannot see.)

jeanna