Joule Thief

[tgraca]

If you can afford them, Fluke and Keysight make reliable instruments.

I got a Fluke 6 months ago.. it couldn't even take a volt reading... I will never buy another one... I'll check into Keysight.
Note that these are standard inductors I am testing and they do show a lot more capacitance than 50-100 turns of 30 gauge
wire around a bolt core, so at least that gives a certain amount of reference. Although the simplified joule thief schematic does
work with standard inductors and without a resistor or capacitor, a resistor or resistor and capacitor IS necessary when working
with the hand wound coils. I am just trying to figure out why, and it seems that the resistance is a major factor. I would like
to think there there is a bit more capacitance to them too, which would make sense. The meters at least show this...

[d3x0r]

can't use a typical LC meter to measure a coil's C... it's only good for a real capacitor that after charging has infinite resistance... a coil will always be less than infinite resistance.... and not the parallel capacitance of the coil..


once you know the L though if you have a signal generator you can approximate the coils' C by finding it's resonance as an open circuit and calculate C from L and F

[tgraca]

If you can afford them, Fluke and Keysight make reliable instruments.

If you guys are in the US and have a descent LC meter, let me mail you a few of these standard inductors and one of my JT circuits
that I am working with so you can report what you find here. I have tons of built circuits with these things laying around and just got
500 of the 1 mH inductors in... lol - please take a few off my hands! Otherwise, I will have to build more shelves! lol

That would really help me and would help anyone following this mess to know why these work really well in a JT circuit without a resistor.
In the mean time, I will find another LC meter.

[Pirate88179]

tgraca:

Hell, those are much better looking meters than what I got.  I don't have time to put up a photo but basically, it is just an nice blue lcd screen on an open circuit board with a 9v bat. clip and an input socket.  Now I really feel like I got ripped, ha ha.

I agree with what you are saying, however.  I have always admired both Lidmotor, and TK in their videos.  You can watch their videos and easily replicate (If it is within your ability, most of TK's are not within mine) their devices.  Many is the time I have taken a screenshot of a Lidmotor video and produced a printed version of his schematic.  I have tried to do better on this as of late, but realize that I am falling way short.

TK has given readings on his JT circuits that I didn't even know were associated with this circuit.  But, that is how I learn.  (Which is why I bought that cheesy meter in the first place.)  I also like how TK uses sockets for his transistors, very easy to swap in others to see the results.  I finally found some of those on Electronicgoldmine for like the 2N3904, etc, but have not ordered any yet.

The more information one can give about a particular circuit, the better.  Another of my new year's resolutions is to attempt to remember to do this.

Bill

[d3x0r]

That would really help me and would help anyone following this mess to know why these work really well in a JT circuit without a resistor.
In the mean time, I will find another LC meter.

http://www.overunity.com/11986/what-i-learned-in-joule-theif-101  all of mine worked best with no resistor.  The resistor made no significant changes when using toroids or cores. 




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descent is to go down.... the long descent into a mine...
decent is a quality qualifier thing...