Joule Thief

[Farmhand]

Well thanks gentlemen, TK I'm just copying the method of not drilling any holes that I see on these threads.  It is very much
a superior method, because drilling holes is messy, fiddly and time consuming. it does require a bit more room, but the leads on through hole parts can be left with some length which allows for them to be reused when replaced.

Pirate, I got the chips from Ebay, they were expensive and I only got two so I figured I would put one through it's paces and I
cannot harm it. Yet!.. I have concerns with the axial inductors that are small and look like resistors because of the resistance they
must have and the saturation current ect. As you can see my coil is very large and I'm sure the size could be reduced but I want it
to be able to pass as much current as possible because the chip adjusts the duty down and the input power at very low voltages is
better if the coil passes current better, the frequency increases as the input voltage drops on these chips.

On the circuit I also used an RBM161M Schottky SMD diode. Forward voltage is about 0.083 by my meter.

I use an inductance meter (cheap one) lowest setting is 2 mH but it measures to 3 decimal places so it measures uH, but not
very accurately below 10 uH. The coil has a very low DC resistance and I might make a smaller better coil for it if I can't find one.

I agree that your black blobs may well be hiding these chips, they come in other voltages up to I think 7 volts can't remember,
don't quote that, but they say they can manufacture parts with regulated outputs in 100 mA increments for special orders.

I wanted 4.5 or 5 volt parts but could not get any.

I'll try to break the chip but I'm not sure what will do it except over voltage input. I guess a small hammer will break it too. 

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Speaking of inductors I don't get how the little SMD inductors can handle so much power for their size, but I think i have a board
with some SMD inductors on it (if it can be found) If I can find one I'll try it out.

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[Pirate88179]

Farmhand:

Thanks for the info.  I appreciate it.

Hey, I found these after doing a little research:

http://www.ebay.com/itm/10PCS-NCP1402SN33T1-Manu-0N-Encapsulation-SOT23-5-200-mA-PFM-Step-Up-/371080306571?pt=LH_DefaultDomain_0&hash=item56661c1f8b

This is the NCP1402 which is a later version.  Start-up is .8 volts and will run down to .3 volts and boosts to 3.3 volts. (Perfect for single led)  You can get it in another alteration that boosts to 5.5 volts with the other numbers being the same.  10 pcs for $3.00 is not a bad price.

Here is the specs link so you can check out other variations offered by these guys on ebay:

http://www.onsemi.com/PowerSolutions/product.do?id=NCP1402 

I believe TK said he has ordered from these folks before if I am not mistaken.

Another vendor on ebay wanted $1 ea. and $5 shipping!!  So, $6.00 for one pc.

Bill

[Farmhand]

Good find Pirate, those NCP1402 parts do look like the improved part with double the output current capability, and they use a higher
inductance of 47 uH rather than the recommended 18 to 27 for the NCP1400 part. Nice.

OK I found a printer board but it has a lot of nice small regular type inductors but with interesting cores, I also found a "resistor" looking
inductor as well.

The two identical ones with black cores and 330 marked on top have about 33 uH each and the resistance is less than can be
measured by my meter. The little green one that looks like a resistor is about 22 uH and has 0.5 Ohms resistance.

The nice looking inductors with the black cores have about 0.6 or 0.7 mm wire, and oddly enough the cores are not electrically
conductive. at all it seems. The little inductor on the other circuit has 1 mH and I can measure some resistance to it as well.

.

[TinselKoala]

Yes, I've ordered from UTSource about half-a-dozen times, and just received the latest order a couple days ago. They have hard-to-find items; I first used them when I needed some obscure Motorola power audio transistors for my old FG and literally couldn't find them anywhere else. They ship from China and usually estimate 3 weeks for normal delivery, but the last order arrived in my mailbox (central Texas USA) in just about a week from placing the order. I was pleased and surprised.
They give you email confirmation of your order, basic tracking, and components are properly packed in anti-static packaging if appropriate.  I got 10 ea. 2sk170 GR FETs for 3 dollars, plus 4 dollars shipping. They emailed me to make sure I wanted the cheap unsorted GR version instead of matched pairs of BL version (a little more expensive).
Their website is a little strange, almost like a "make offer" pricing, but now they have set up a big EBay store section which is probably easier to use than their website.

The little inductors are neat. Notice that the color code is the same as for resistors: Red Red Black is 2, 2, and 0 zeros, or 22 uH. The cylindrical ones 33uH can be wrapped with another winding over the outside and then used in transistor JT circuits, or of course can be used as single inductors with the booster chips. Some of the cylindrical ones in that footprint I've found have a biasing magnet as part of the core. It it that type I used, with an added winding, for my 6 NE2  HVJT using 2n3055 or 13003 transistor.

ETA: I'll bet you could put a few turns around that green 22uH baby, as a "primary", and it would work in a transistor JT. I am finding that just about any core material (even air and ferrite) will work and just about any turns ratio too. Of course for the "best" performance in terms of efficiency, low voltage, low current, etc the parameters need to be much more carefully chosen.
For example I just made a JT using Conrad's 2sk170 circuit; for the inductor I used a little cylindrical ferrite bead 10mm long x 10 mm OD that was a choke thing slipped around a power supply wire originally, no windings. I wound it with about 80 turns of #34 and 5 turns of #24 and it works great.

[Farmhand]

Tinsel any idea what the other parts are in that picture ? The two little black things were labeled "L" and the little blue things were
Labeled "C", I thought the black things might be some kind of low value inductors and the blue things capacitors, but I can't measure
any values for either, the blue things look like little gas discharge tubes and have 470v and 0306 written on them.

Anyway, The printer board is out of a HP printer and has a few more neat parts on it.

Pirate these chips can power as many LED's as the input and the output current limits will allow.
Three works well with a 3 volt 100 mA output part.  A 200 mA 3.3 volt part could run 7 x 5 mm LED's at full brightness.

Here's a comparison of 3 x 5 mm LED's in parallel, powered in the first pic with the circuit supplied by only just under 0.5 volts.
Second pic is with the same load but supplied by just over 1.1 volts. In the latter the output voltage regulation is active. But in
the first pic the input is so little that the circuit cannot quite get to regulation voltage of 3 volts.

3 volts across the 3 x 5 mm LED's in parallel makes them really bright, so bright I cannot look directly at them without it causing
eye pain.  I guess with only 3 volts the LED's will last longer, (they're cheapies).

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