Joule Thief

[MarkE]

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

Spark Fun sells power converter circuit boards with NCP1402s on them, complete for $6.  You can unsolder the inductor and connect up your other circuitry.

[MarkE]

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.

..

The big differences between the NCP1400 and NCP1402:
NCP1400 is a fixed frequency discontinuous conduction device.  It is ideal for low power devices and draws almost no current when there is no load.
NCP1402 is a variable frequency continuous conduction device.  It handles higher current loads, but is not ideal for extremely low current loads, or no load.

Each works well in the appropriate application.

[TinselKoala]

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.

..

Clear package packing tape works really well as a PCB resist. You can tape the whole copper side, then carefully cut traces out with a razor knife and straightedge, to make very thin traces and pads for the surface mount devices. You can also buy sheets of rub-on resist patterns that will lay down the whole DIP or SOT pattern at once, which you can then connect up with drawn resist or tape, etc. I have even seen methods using laser printers and clothes irons; print the pattern with full dark contrast on a sheet of transparency film or glossy magazine paper,  and then transfer the toner pattern to the copper with the hot iron.
For hand drawn, I've found that the ordinary black Sharpie marker works just as well as the "resist pen" industrial grade Sharpie and doesn't dry out as fast in the pen, and is quite a bit cheaper. (using ferric chloride etchant, other etchants may not work with the plain Sharpie)

This stuff comes in very handy both for removal and for reassembly of surface mount components, it actually does what it says on the tin:
http://www.chipquik.com/

[Pirate88179]

Spark Fun sells power converter circuit boards with NCP1402s on them, complete for $6.  You can unsolder the inductor and connect up your other circuitry.

Thanks mark, I will look into that.  I do have some 1/4 wide copper tape that I could cut into thinner strips, kind of what TK is doing.  (Thanks for the idea TK)  I have a schematic of the chip but am not sure where everything should go so maybe that sparkfun board would help me with this.

Thanks,

Bill

[TinselKoala]

https://www.sparkfun.com/products/10967

I like SparkFun. Especially the little red cardboard boxes they ship stuff in.