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Sharp GH04C05B9G 5W 440-450nm

RedCowboy

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Andratos95

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You would use a rheostat rather than a potentiometer.
I'm not the best person to teach you about the construction of op-amp based drivers, I'm still learning myself.....that said you can educate yourself with some searching.
Thank you again for the valuable info! I think I'm quite convinced about the linear regulator idea as a first build. Just a quick question... This sharp gh04c05b9g diode, I imagine it needs to be inserted into a module and then also insert the module into a heat sink. I was thinking of this heat sink, does it look good to you?



Screenshot_20220506_210532_com.alibaba.aliexpresshd.jpgAlso, I see this comes with a lens, but I read in your earlier posts that you can use a G2 or G8 lens. I seem to have understood that the G8 lens has a larger focal distance so that the beam looks more collimated, which is better to get a nice low-divergent beam but worse at burning things (although I suppose that at almost 5W, that's not really an issue maybe?). So, I'd like to buy a G8 lens, but I am not actually sure of what they look like. I searched on AliExpress and this is one of things that pops up, is this a G8 lens?
Screenshot_20220508_172645_com.alibaba.aliexpresshd.jpg
Or is it supposed to be much more expensive than that?

EDIT: Actually I doubt that will fit since it says it's a 9mm diode... What about this lens on eBay?Screenshot_20220508_173154_com.ebay.mobile.jpg
 
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RedCowboy

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The Chinese G8 lenses I bought with the wide opening that look just like the one you have pictured worked just fine, however some of those housings have sloppy tolerances and use poor materials, I bought some that wouldn't move heat worth a dam........luck of the draw I suppose, use some heat sink compound at the gaps if you try to use them.
 

RedCowboy

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These are the G8 lenses and sellers I have bought them from, they are all very good and my favorite for the sharp488, all 520's and the multi mode 405's and 445-465's where you want a better looking beam in the far field, you can burn with them on the desktop as well but what I do is drill out a thumb wheel and run an M9x0.5 tap through it to use as a lock, you can also use them to lock down you focus along with an un-drilled thumb wheel on your hand helds.

NOTE: Not all lenses advertised as G8 are actually 8mm FL but the ones listed below are.

SANY5897.JPG
SANY5908.JPG






COPPER MODULES HERE and HERE



Mounts Here




 
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aaronnoraa

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I really like the idea of building the driver by myself and actually understanding how it all works, so this actually seems very nice. But I have a few questions... If you were using a current sense resistor of 0.33Ω, and the reference voltage on the LM338 is 1.25V, your resistor would have to dissipate 3.75W of power. However with your trick of using 3 resistors in parallel, each one only dissipates 1.25W so... That's a "trick" for using lower power rated resistors, right?
I'm not him but I'm guessing it was a trick to get .33 ohms with what was on hand and probably also happened to lower the power over each resistor enough to be in spec. Useful tools for making an LM317 or LM338 or LM350 current regulator are

Current to resistance value calculator for LM338/350/317

and
Parallel resistor calculator

The TO-3 LM338's are where it's at but also expensive. Regardless of the package you choose, the heatsink should be CHONKY. They get HOT running at high current and if you're not fan cooling the heatsink they're attached to you need serious square inches of radiating area for sustained operation.
Say I wanted to adjust the current with a potentiometer... I would need to connect it in series with that (equivalent) 0.33Ω resistor, right?
Yes, and as he said make it a rheostat, just look up how to convert a potentiometer in to a rheostat. I'm sure you're aware but the addition of the variable resistance will only let you get it dimmer than the base resistance.
But then the potentiometer also needs to dissipate a large power since it's in series, right? So I need to buy one that is also rated for high power?
High enough power to be in spec, yes.
:)
 
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