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pot before or after resistor?

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sometoymachine

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About to get all my goodies in to make a DDL driver. Thought i had all my thoughts together when I just hit a kink. I've become unsure if I should put my pot right after the LM317 and before the resistor(s) like in this guide that so many people mention to beginners :
Laser driver - It can be done

Or if i should use a resistor across the LM317, before the pot like in this:

YouTube - DIY: How to build a laser diode driver

The second one seems more logical to me because the current will have been set at max and the pot will only adjust from max and downward.
 





Shouldn't matter, resistors in series just add up, addition is commutative. Put whichever is rated for higher Watt first.
 
Just use 1 resistor to set it. The pot is really not need as your not going to be changing the current once you have it put together.:)
 
Only reason I thought I may need the pot is bc it's a lpc-815 and I was gonna use a 3.3 ohm resistor, setting it 380mA max and use the pot to turn it down if the hestsinks didn't do a good enough job. Still going to be my first build so I didn't know. But if you guys think I don't need it then I will not put it in bc it would definately keep my driver smaller.
 
Post a Picture of your Heatsink. Then i can tell you if the current is going to be to high for that heatsink or if its enough if you dont mind. :)
 
How do you plain on mounting it to that heatsink.? If you are going to drill a hole in the center of the heatsink where the LM is sitting and stick the Aixiz module there you will be more then fine t 380mA.
 
The aixiz module is going to be inside a much larger heatsink that I'm sure disperses heat better. That HS was for the LM317 itself bc I heard that it is the other component that gets hot. Is this more uselessness?
 
I thought you were talking about the Diode getting to hot. :) Anyways that is more then enough heatsinking for the LM.:)

Good luck.:beer: Post some pictures when you finish.
 
Quick question about resistor choice. Guys talk alot about 10ohm resistor. but I notice they come in different watts. Is there one that's better then others?
 
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