Joule Thief

[sparks]

   The blob could be a current control device.  Allowing for a smooth output voltage so that load is even no matter the state of the battery charge.  Most of these chips internally are either all on or all off with the duty cycle adjusted by the load requirements.  The choppy ouput is then filtered using internal components to whatever degree of dc is required by the load.

[Pirate88179]

Sparks:

This sounds very plausible.  I really think this blob is not tall enough to be hiding any chip or cap or any other electronic component.  What you are saying is that the blob itself is a component which would make sense in that all of the board traces are connected to it.

Thanks for the input.

Cap:

It is about time I got a promotion.  Too bad it does not include a pay raise, ha ha.

Bill

[mscoffman]

Sparks:

This sounds very plausible.  I really think this blob is not tall enough to be hiding any chip or cap or any other electronic component.  What you are saying is that the blob itself is a component which would make sense in that all of the board traces are connected to it.

Thanks for the input.

Cap:

It is about time I got a promotion.  Too bad it does not include a pay raise, ha ha.

Bill

@All

Usually those blobs cover a silicon IC chip of some type, directly wire
bonded, most likely to through-board metal clasps. One can buy the
silicon die for slightly less then the cost of a pre-packaged IC for very
inexpensive electronics devices such as this. Pressure welded wires,
then a glob of epoxy adhesive is put over the top sealing the silicon
chip directly to the circuit board.

Most likely the IC uses the solarcell output to detect when to turn the
Led on after dark, as there are so few other components... I'm sorry, I
do see a photoresistor in the picture.

Unfortunately, in my experience these inexpensive lawn lights use
very inexpensive defective compromised solarcells with abnormally
low optical efficiency levels. Your mileage may vary, but it seems
like the name brand manufacture has been using the same
compromised solar cell production lines for years so that their
customers don't get any "ideas". If you find some that are
great, please let us know. (should be in the 7%->20% wattage
efficiency range)

These lawn lights could very much use a JT switcher, but in my
experience are straight DC and very inexpensive to manufacture.


:S:MarkSCoffman

[detrix42]

@all:  I need some help here.  I do not have an oscilloscope, and so I can't do this my self.  I would like to know exactly what is necessary, component wise, to get a joule thief to oscillate at 174,926Hz.  Or let me know if this is even possible.  Thanks for any help.

Detrix42

[jeanna]

@all:  I need some help here.  I do not have an oscilloscope, and so I can't do this my self.  I would like to know exactly what is necessary, component wise, to get a joule thief to oscillate at 174,926Hz.  Or let me know if this is even possible.  Thanks for any help.

Detrix42

Go to allelectronics and get the Tor-23
That is what is necessary, by the way. It mostly is limited by the toroid.

When you get it, wind a center tapped wind with 5 on 1 side and 8 on the other side of the center (which is the part to connect to the pos of the battery.) I assume you are familiar with most of this. If you are not sure, please ask more q's.
Connect the outside end of the side with 5 Turns to the base resistor (in this case the 5k pot) , and the side with 8 T to the collector.

Use a 5K pot and tune the pot first to 1k which should give you around 50khz, then raise it.
You do not necessarily need to raise it much.
I had these numbers with a 2N3904, and I think the 2N2222 might be better for this, so get a couple of those while at allelectronics too.

I got 203khz when I was working with my multiple secondaries circuit and using the tor-23, so you might read my posts and look at the drawings from the thread called AC from a joule thief (or something like that) and also take a look at the 6 or 7 videos I made about that circuit.

I do not believe anyone can tell you exactly what you will get because the transistor you have will be different from others, but if you slowly sweep the 5k pot or 10k you will find what you want.

I had about 85 turns of 30 gauge wire and managed to get 85v and I might have had enough room for 95 or 105 turns, but you need 164 spiky volts to turn on a neon, so you will only get about half enough to turn on a neon with this core.

You might get a tor-61 while you are ordering. It has the same cross sectional area with a bigger radius so you can fit more turns, but I have not yet seen over 70khz. (but I wasn't trying either, so try one.)

jeanna