Your schematic looks fine, and nearly matches the sample circuit from the 317 datasheet. Using your values, it looks like you would be regulating to a 4 mA current. Your results will vary depending on the load you are using. No load should result in a 1.2V output, a diode may result in the forward voltage of the diode being the output, but you may need a parallel resistive load to trigger the 317 to get the output voltage above 1.2V. When you get your parts, breadboard and test it out.
Since you said you were building a laser pointer, you may want to look into a voltage thief circuit instead so you can run your pointer from a since cell battery, instead of what I'm guessing would be a 9V. It does need a few parts that you may not have, but overall it's not a complex circuit either.
For sure I am going to spend some time on a breadboard testing out various things. Ideally I'd like to run on these 7.2V rechargable tool batteries I have. To do that I might need to put a voltage regulator on those though. That shouldn't be an issue. I am getting 10 LM317 ICs with my diode order.
Your schematic is looking good. Glad to see you did not put a capacitor on the output since you are using it for a constant current regulator. Some people say to put them on there to stabilize things, but you should not have one when using it as a current regulator.
I can't wait to see your project when it is done.
What voltage is your laser diodes you are getting? If you have time to wait...here are some that I bought..but they are in china and will take a little while to arrive....
The Operating Voltage is 3V and the Operating Current is < 45 mA....just a thought.
Thanks for the reply. I was wondering about the output stability capacitor. I've heard not to use it, so I left it out. I am shooting for 5ma with my output. That is what the diodes I am getting are rated for. They are supposed to be 3V diodes too. I am getting a 10 pack, so I probably will blow a couple of them up, just to see what they can really do. It is not like I need 10 pointers. Just one good one should suffice.
I am thinking about heatsinking it too. They come in little brass holders, but I am thinking a larger aluminum heatsink might help them out? Until I actually get the things I don't really know about any of that. Supposedly this brass barrel they're in has an adjustable collimating lens in it. Some say the whole affair is very fragile too, so I might not be able to mount them into a press fit heatsink too easily without breaking them?
Then again I have some machine tools so I might be able to rig something up here.
Depending on how this goes I might post the project here. As of yet I have not built anything though. Although I have designed some simple circuits already. I'm waiting for the parts I ordered to arrive. I have researched the topic a bit on the 'net and I am thinking about building a very simple current regulator for the laser doide I am getting.
This is all new to me though so I figured I would post my schematic here to see what kind of feedback I get about it. I may have missed something critical that I am not aware of.