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DIY Homemade laser diode driver

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rhd

rhd

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Lol - thanks for the suggestion :)

To clarify, I have no trouble building an LM317 driver for this project - except that I didn't have any lm 317s on hand.

For future reference, there's something screwy with the LM338s I had (and potentially the IC in general). I'm feeling like the reference voltage was different.

Regardless, I used a 1084, and all is well :)
 





rhd

rhd

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Lol, thank you ;)
I think I've built a hundred DDL circuits with LM317s, so I promise, I do know where to get them ;)
The reason I don't have any, is that I don't use them any more. They've been replaced in my driver component box by 1117s, 1084s, and 1085s.

Having said that. There are times like these where an LM317 still works well (2 cells and a low Vf side)
 
HIMNL9

HIMNL9

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LM1117 is identical, just a bit lower in dropout ..... you can use it same as the 317 ;)
 
rhd

rhd

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HIMNL9 said:
LM1117 is identical, just a bit lower in dropout ..... you can use it same as the 317 ;)
Click to expand...

*not totally true*

1) The maximum current is lower
2) 1117s require an INPUT capacitor, in addition to the output cap
-- though sometimes you can get away without one
 
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atifmonkey

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so how do i add a profile pic? like when people post a comment, you can see a picture on the side? how do i do that?
thanks
 
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joniverson

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Hi Folks,

This certainly is still an active thread after the 3+ years since I've been here. I do have a question though. I am in the process of building a 445 1 watt unit and I'd like a DIY driver. I am wondering if this one will work. I built it for the reds I used to have, but this laser will have quite a bit more power than those.

If it does work, what components need changed or adjusted? If not, what DIY schematic is recommended?

Thanks in advance,
Jon
 
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joniverson

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Thanks, but I wonder what current I should be setting the 445nm 1W blue for? 6 or 9 V input. Ohms law tells me 160 mA or 110 mA depending upon voltage.

BTW, I have a couple of the DX 18V 5 W cree drivers on the way, but after reading about your surprising experience with them and your "Blue Ninja", I don't know if I want to use them.
 
rhd

rhd

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joniverson said:
Thanks, but I wonder what current I should be setting the 445nm 1W blue for? 6 or 9 V input. Ohms law tells me 160 mA or 110 mA depending upon voltage.
Click to expand...

That's not how it works. You don't need to think about ohms law. Just decide on the current you want - that's it. Once you know the current you want, read up on that DDL driver. You can set it to pretty much any current you'd need for any laser diode we use. You don't need to worry about voltage either as long as you supply at least what your diode needs + 3V. If you just read up on "DDL" drivers, there is an ABUNDANCE of info on pretty much every aspect of DDL DIY driver builds imaginable. All of this is explained in depth in a dozen or so places here :) The link I sent you is a good starting point.

I wouldn't use that DX driver again - at least not the way I used it in the Blue Ninja. I'm going to do a follow-up to the blue ninja actually, and it's going to be based on a DDL circuit (though not an LM317).
 
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joniverson

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Ok, a little more research on my part today. I hope this is correct. If I am to design a proper regulator based on this information: http://laserpointerforums.com/f38/blu-ray-445-diode-test-current-levels-long-life-44746.html
then I need to design for 4.5V @ 1000mA to be "safe" for a 445 1 w. So, if I am correct, during my tests with the dummy load, I want to see 1000 mA current. However, I see a potential problem. If the 445 has an input current of 4000 mW (and this is based on the site I referenced above), won't this be slightly too much current for the LM317 to handle? IIRC, the 317 handles up to 3 amps heatsinked.
 
rhd

rhd

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Regarding your comment "If the 445 has an input current of 4000 mW"
- Current is measured in mA (or A), not in mW (or W)
- Plus, 4000mW is way too much anyway. From the notes in that post, none of the 445 data actually came from real 445 diodes. Just from info Nichia provided. In fact the post was originally written (though it has been updated since) before 445s were widely available in 2010.

I think you should do a bit more research. Though to be honest, I think my suggestion is still a good/simple one.

1) Build a DDL circuit. I gave you the link in my post above.

2) Choose the current you want to drive your 445 at. Just read the forums a bit and you'll get a sense for the current people are setting theirs at, and the relative levels of success they have at various currents.

It's that simple - really :)
The DDL circuit can be used for a huge range of currents with just a bit of math and resistor selection (all of which is in the resource I linked you to)

Good luck!
 
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anselm

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4000mW is way too much anyway.
Click to expand...
Hmmm, 4000mW in the form of 4V x 1000mA actually pretty much nails it as for input power.;)

When you build your DDL driver, use a 1Ohm resistor for 1.25A current that's a good and safe value.
 
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joniverson

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Sorry guys. I had my math way off. Should have known better, but it's been over 3 years since I worked with this stuff, any electronic stuff for that matter.

So even if the input was 4000 mW @ 4V, this would only amount to 1 A (I=P/V). Of course, probably there are more losses within the circuit so I expect the dummy load will have to be used to get a proper current for the diode. I'm thinking of a wattage setting of 900 mW since I'll be using a big heatsink. I will have to see what the dummy voltage and current are to get the correct wattage using your page (thanks for that!). I don't have a laser power meter, so will just have to do it all by dummy first.

Only question concerns batteries. My old lasers that I built used packs of rechargeable AA's as I recall. I see most people are using Lithium Ion or similar, but I'd like to stay with what I have. I have probably 10 AA rechargeables available for use. Looks like folks are using 6 in series for the 445.
 
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