Step-up DC-DC converter IC

[**DONOTDELETE**]

Phantomas2002:

Thanks for the tip ... glueing a PCB layout onto the copper and then cutting it with a Dremel tool sounds like a workable way to go without etching.

I think the Dremel bit you are referring to is a 5mm burr. I've seen them with round and pointed tips ... the cutting part has file-like edges on it?

For those of us without AutoCad, any decent vector-based drawing program that provides accurate measurements will work (Corel Draw, Adobe Illustrator, etc.). Photo or painting software (Corel PhotoPaint, Adobe PhotoShop, PaintShop Pro, etc.) will not work. The ability to scale the size AND retain high resolution is critical. Hand drawing will work if you are that talented (I'm not).

I have yet to try doing an image transfer onto copper from a laser-printed page, but if it works as well on copper as it does on some other materials, I'll detail the process here. It would mean being able to cut the traces closer together, with better accuracy (the thickness of paper on top of the copper will cause distortion).

I'd love to have some workable circuits in four weeks! Hopefully, all the parts will be here by then.

Thanks again ... you are a fount of information.

Mark

 

[jeff1500]

Here's someone who looks like he did it using a pre-manufactured circuit board he bought for $20. He's got a bunch of photos at this link:
http://www.ResurgentSoftware.com/Perfect_LED_Light.html

Quote: The step-up circuit used in the
micro design is the LM2621 and is available in a pre-assembled "kit" for $20. National Semiconductor says this about the product, "The LM2621 is a high efficiency, step-up DC-DC switching regulator for battery-powered and low input voltage systems. It accepts an input voltage between 1.2V and 14V and converts it into a regulated output voltage. The output voltage can be adjusted between 1.24V and 14V. It has an internal 0.17[Ohm] N-Channel MOSFET power switch. Efficiencies up to 90% are achievable using the LM2621." Once the leads are cut off the circuit board, it is only 1/2" by 3/4" rectangular and will fit inside the headpiece of the Petzl Micro headlamp.

 

[**DONOTDELETE**]

jeff1500

That, my friend, is hard to beat. Great find!

Mark

 

[jeff1500]

http://www.national.com/pf/LM/LM2621.html

Here's the spec. page with a link to purchase the board. They ship FedEx or First Class mail.

 

[**DONOTDELETE**]

Just ordered one. Look forward to seeing how it performs.

Thanks again!

Mark

 

[KenBar]

<BLOCKQUOTE><font size="1" face="Verdana, Arial">quote:</font><HR>Originally posted by jeff1500:
[QB]Here's someone who looks like he did it using a pre-manufactured circuit board he bought for $20. He's got a bunch of photos at this link:
QB]<HR></BLOCKQUOTE>

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1000 thanks for this link...I just fed-x'd one. I have been looking for this for some time....at a reasonable price!

 

[Go Go Gadget Flashlight]

Here's a link I found for soldering SMT parts without fancy equipment. http://www.geocities.com/vk3em/smtguide/websmt.html

And a nifty idea for a "third hand" to hold the parts while you solder: http://www.psnw.com/~kd7s/smdhd.html

There are a couple options for soldering irons.

First, reshape the tip. Take the tip out of the iron and file away until you have a
nice, small point.

Next, make it variable heat. Go to any old hardware store and buy:
$1.50 A cheapo extension cord
$0.40 A single gang wall box
$8.00 A lamp dimmer
$0.30 A cover plate
$1.00 A nite lite (optional)

Cut the extension cord near the outlet end.
Feed the cut ends into the gang box.
Wire the dimmer to the extension cord's wires.
Mount the dimmer and cover plate to the gang box.
Plug in the soldering iron (and optional nite lite) to the extension cord.

Shazam! Homemade $12 variable temp soldering iron with optional display (the nite lite).

 

[**DONOTDELETE**]

Great links and tips. Thanks!

Mark

 

[jeff1500]

http://mikro.e-technik.uni-ulm.de/persons/lares/LED_flashlight.html#V2

Here's a two AA Mag light with two white LEDs and a Max1759 chip.

 

[jeff1500]

http://focus.ti.com/docs/prod/productfolder.jhtml?genericPartNumber=TPS60100

This is a TI chip that does not need an external inductor.
http://www.ti.com/sc/docs/psheets/abstract/apps/slvu016.htm

This is the tech manual for the evaluation kit ($50., too much for me). It has a jumper to set the output voltage to 3.8v

 

[jeff1500]

http://elm-chan.org/reports/led1/report_e.html

This is a link to a hand made 1 AAA 1 LED light It shows the circuit diagram.

 

[**DONOTDELETE**]

Hallo world,

just some of you an idea to make PCBs by your own .
I started in a practical way a lot of years ago by manufacturing my first PCBs at home.
Double sided PCBs are no problem. I used a normal grafics tool (e.g. Coreldraw)
for designing the two pcb layers. I printed the layers on normal paper with a laser printer.
A canned chemical (I don't remember the name) made this paper transparent for UV-light.
For the exposure of the PCB (normally it's easy to find PCBs with prepared positive resists on both sides) with UV-light I used a small tanning booth source for ~5min, where I covered the transparent paper positives with a glass plate (should be tested first).
The devolpement (I think it was sodium hydroxide dilution) after exposure with a chemical is easy to do (~2min).
The final step is etching, which works fine normally, when the etching liquid is warm (~50°C) and the bath is continuously undulated.
Final drilling of holes is no problem, when
the exposure-alignment of the two layers has been done precisely enough.

 

[**DONOTDELETE**]

Ufff - I forgot the link to my previously linked web page for our miniature LED flashlight project: http://mikro.e-technik.uni-ulm.de/persons/lares/LED_flashlight.html
I have 3 PCBs of V1 and V2 to give away.
Anybody interested?

 

[Luff]

My first attempt at the LT1308b circuit is a dismal failure

Very disappointing. I'm beginning to understand some others' hesitation to make these boards. Oh well, I don't have any other circuits to play with until the National Semiconductor evaluation board arrives.

There are so many little things that could be wrong, it might be easier to start over than to troubleshoot this one. A SEPIC design was probably not the best choice as a first SMT circuit to build

but I've sure learned a lot doing it. Soldering was MUCH easier than I expected. I followed others' advice from CPF and used lots of flux (what a difference it makes, too!)

Making the pcb was also easier than expected. I used Corel Draw to create the copper template and then printed out a mirror image of it at the correct size. Placed that over the copper circuit board, toner side down, and ironed it. I rinsed it under water and rubbed off paper as it dissolved. Voila. Had to touch up a few spots with a marker before using the Dremel tool to carve out the copper.

That part went great (I'm not sure, however, that gluing the printed circuit onto the copper and then just cutting through the paper and copper wouldn't have been easier. I'll try that on the next board).

I think I'll tackle the Maxim 1701 next while I cogitate on what I did wrong with the Linear Tech board. The Maxim circuit is slightly less complex, but on the other hand, since the Maxim PDF doesn't have a copper template to follow, it'll be my first schematic-to-copper attempt.

I do wish I remembered more from those EE courses I took 35 years ago ... but then some of this stuff didn't even exist then.

 

[hank]

Hello Roland! Glad to see you here.

Your page at the University of Ulm (link posted just above)
was the first LED conversion I came across, before finding this site.

I'm probably too busy to use one of your PCBs now, someone else here with more time should ask for them -- if no one does, when winter comes I'll have time to build something.

So if you'd like to, send them to me in California and I'll either use'em or pass them on when someone asks. Tell me what you'd like in return, postage or whatever in trade for them.

The little Maxim board you designed your MagLight conversion around looks easy to use.

 

[jeff1500]

Roland,

I really like the 2AA Maglight conversion that you made. I'd like to try to make one but I can't imagine how to assemble such small components. I've been thinking that you have special equipment available. How did you do it?