I GOT IT WORKING!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! AFTER A MONTH OF TINKERING WITH THIS STUPID CIRCUIT I GOT IT WORKING!!!!!!!!!!!!!!!!!!! :lol:

I breadboarded it and fiddled around with it and somehow got it working, even though it is exactly the same as on the PCB. How or why it is working now is totally beyond me! Now I just have to make a PCB for it. I just got a digital camera so I thought i'd take some pics :lol:

The first pic is taken from across the garage.

Its only consuming 270mA!

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I'm no electronics god, i just talk too much.

 

Horray!

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Uncle $crooge

 

Congratulations!!!

GOOD work done

 

Nice work, i've been following this thread because i'm interested, but haven't made any posts because I don't even know how it works :lol: . I suppose you'll want to be putting it into some sort of torch body now?

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Angry!? I'm absolutely electrolytic!

Music web page:
http://www.music-playground.net/artist/drem/

 

Hi Dr. EM,
Its DC to DC converter works by its oscillator driving a power transistor to conduct a high current in an inductor. Then it quickly stops the inductor's current and it develops an inductive voltage spike as its magnetic field collapses. The voltage spike charges the circuit's output capacitor to a voltage higher than the supply voltage. The IC senses the output voltage and regulates it as the battery voltage drops over its life. :lol:

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Uncle $crooge

 

Nice pic audio :lol:

Yes, Im going to mount it in a torch now. I'm thinking about buying a 3 D-cell maglite and putting it in there. First I'm going to try it with my 2 D-cell maglite.

In the 3 D-cell maglite, if I put two batteries in parallel, and one in series with those two parallel, ill still have 3 volts right? This would extend the life of the flashlight considerably. Not only that, but ill have a very advanced flashlight that can also be used as a blunt object weapon :lol:

Im gonna start on the PCB in eagle right now. Ill make sure to post more pics of the finished product, and the beam that itll be able to throw with a reflector.

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I'm no electronics god, i just talk too much.

 

Hi Zach,
If you have one battery cell in series with others then it will fail just as quickly as if the others weren't in parallel. When it is discharged then it is a high resistance and the circuit won't work.
Fabricate a dummy cell for the 3rd one. :lol:

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Uncle $crooge

 

R1 would likely cause problems the way you have it mounted on the board. 33mOhm is pretty low and the contact resistance of the board is probably higher than that, inconsistent too.

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I thought what I'd do was I'd pretend I was one of those deaf-mutes.

 

I agree. The wire from pin 5, should go directly to the top of R1, not via the board contacts. Also keep it as short as possible.

 

Aw shoot, i guess ill just stick with 2 D-cell.

I hope that this change won't screw anything up when i put it on a PCB.

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I'm no electronics god, i just talk too much.

 

No your PCB will be fine, though don't return the main current through ground through the same trace leading onto the ground pin of the chip. Of course this is already a pretty inaccurate circuit so it's not really anything to worry about. Soldered connections will not have resistances on the order sometimes possible with the protoboard. And the protoboard is hard to predict, you could have a great connection on one pin and a lousy one on another. Or it may heat up and change temp. No prob for most jobs but a 33mOhm current sense is a special issue.

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I thought what I'd do was I'd pretend I was one of those deaf-mutes.

 

The pcb layout in the Silicon Chip magazine project looks like it has the high current paths separate from the sensitive ones. 8)

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Uncle $crooge

 

The silicon chip magazine's PCB is not the correct size at all. In my PCB the track sizes are also much bigger, mostly .032". The different loops are also kept away from each other.

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I'm no electronics god, i just talk too much.

 

I have just come into this thread.

I saw a data sheet for a switching regulator a few months ago and it recommended that the ground tracks should all be connected at one point, ie. a "star" connection.

This prevents voltage drops across the tracks carrying the high currents affecting the sensitive areas of the circuit.

The same could also be done on the positive supply side also.

Len

 

I found the data sheet I referred to above. See page 24

Len

Attached Files

lm2587.pdf (819.6 KB, 29 views)