Joule Thief

[Pirate88179]

Farmhand:

I am glad to see that you are getting some of the 1402's.  I plan on getting a few when I get paid.  Going back to your earlier photo with the 1400, I believe I see an axial inductor along with your wound coil?  If so, why did you do this?

I am also confused by the 1402 website data that says you only need to add three components to get an efficient circuit.  OK, we have the 1402, a resistor and an inductor....what is the other component they are talking about?  Are they counting the led here?  Or, a regular diode?

I will have more questions once my 1402's get here but it will be a few weeks before I can order.  Keep up the good work.

Thanks,

Bill

[Farmhand]

Hi Pirate, The 1402's are almost the same as the 1400's except I think the internal mosfet is rated for more current. I did remove an axial inductor from a board to measure it, but on my 1400 board I placed an indicator LED with a 1 K resistor in series with it, the main external components are --

1) inductor (low resistance)
2) diode (best schottky)
3) input capacitor
4) output capacitor.

We can say that there are 3 different external components, but 4 total.

I will take a close up of the board and I hope to make some PCB art with places for some extra components we might want
like CSR's and such, any suggestions on things to make places for on the board is welcome.

I am so impressed by the NCP1400 that I just had to get some NCP1402's.

Do you have some solder paste, I found it is invaluable for soldering fiddly parts and for tinning traces, I simply put a bit of paste
where I want to solder to use it like flux and the solder flows into the parts much better neater and quicker, quicker means less
chance of damaging the tiny parts.

If you want I will make a PCB or two for you and post it to you, but it might take a couple of weeks, just a thought. I never know
when I'll get laid up with spine pain. Lately I'm doing pretty well though. If things go bad enough they always get better, somehow. 

I think you're trustworthy, so just PM me if you're interested in the PCB. I may have some other extra parts you might make use of as well.

Thinking of easy ways to construct a smallish mag-carbon battery, the last one didn't last long but it gave current like mad. 
I think the separator is important.

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[Pirate88179]

Farmhand:

Thank you very much for your kind offer.  I will pm you...however...I too have some parts I can send you that you might find useful.  I can send you some new flash circuits (400 volts when modified) and also a few of those garden light circuit boards I bought that have that chip I was looking for on it.  It only works down to .8 volts but also has the ability to switch from solar charging to battery power.

I think I like the 1402's better though.  I want to make a nice light for folks that they can run on "dead" batteries and, going down to .3 volts sounds a lot better to me.  Plus, as you pointed out, I can run several leds from it due to the power abilities of that chip.  I can also send you a set of my universal magnetic battery connectors (version 3.0) to test before I go to market with them.  I want TK to try a set of them also.  They work really well and, a buddy of mine suggested that I should offer a version that has alligator clip leads on them as well.  I am considering this.

Bill

[Farmhand]

Here's a closeup of the hand drawn board, I had trouble making the traces small enough for the chip so I made the traces to take
the chip on a five pin adapter, but when I tried the chip on there I found that if I solder pin 1 and 2 on the same pad I could put the
chip on the board. Also the little three LED board is there, I can drive it from either end one way I can measure current, or I could
chain another load after the LED's.

..

[Pirate88179]

Farmhand, nice job.  I just received 10 pcs of the 1402's....wow...are they tiny!!!!

I think they call it the SOT-23 package but, i can't even see the damn legs sticking out of the package, ha ha.  I can make a small circuit board for these but, how the heck do I test my set-up first to determine if I have the correct hook-up?

I will have to think about this for a bit I suppose.

Bill