Just making sure im right with my infoCHANGED PLANS, 6x 405 lm317 what resistor?

[extremeodd]

Well Im waiting on my driver to be replaced so in the mean time I would love a working laser. Im thinking of running up to radioshack and picking up a lm137t, 1ohm 10w resistor and a random cap. Im not worried about reverse polarity protection since Ill make damned well sure the batteries are in right. From everything Ive read a 1ohm resistor on an lm317 will give about 1.2-1.25a output correct? Will this run alright on 3x 3v cr123a's? I was thinking 9v but didnt think it had enough output to deal with a 445 diode. This setup will only be used till wed of next week or so.

EDIT: Decided to wait on getting my driver back instead of this, dont have enough lithium batteries :yabbem: Now I want to use this for a SF-AW210 405nm. I want around 170-180ma, doing the math thats roughly a 7ohm resistor. You cant buy one at radioshack but I was thinking 2x 15ohm for 7.5ohm, which should be a good safe level. Yet again am I correct with my math? Also how much heatsinking do those beasts like? I was thinking of getting it from modwerx and this Laser module w/ heatsink and AR coated glass lens (405-450nm) - $12.99 : Modwerx Shop since it has a glass lens. I figure I could still attach a smaller heatsink below the fins with the backend of the module in place.

 

[jayrob]

Re: Just making sure im right with my info (lm137 powering 445)

Yes a 1 Ohm resistor will give 1.25 Amps with an LM317 and 9 volts is plenty of voltage...

Find a 1.5 or 2 Watt resistor to handle the current.

The other thing is, at 1250mA's, you will need 3 X 18650's. Because CR123's won't put out that much current. (I doubt it anyway)

Maybe RCR123's, but they won't last long at that current...

 

[extremeodd]

Re: Just making sure im right with my info (lm137 powering 445)

How low will the current be with a 9v battery? Im assuming somewhere in the range of 500ma.

Also I know the cr123s I have wont last long, using them (2x) with this diode would kill em after roughly 20-30 mins of use before they drop to an unusable level. However they can handle fast discharges no problem quoting wikipedia here "Lithium iron phosphate (LiFePO4) batteries are the fastest charging and discharging, next to supercapacitors"

 

[jayrob]

Re: Just making sure im right with my info (lm137 powering 445)

You mean those little 9 volt transistor radio batteries?

That won't work for much current at all...

 

[extremeodd]

Re: Just making sure im right with my info (lm137 powering 445)

If you mean the same 9v that goes into a smoke detector, then yes one of those. I know they dont output much but this is a temp setup till I get my driver back from survival laser.

EDIT: Welp I decided to scrap this little project, dont have much for lithiums lying around so I dont have a good power source for a 1w+ lm317 setup. Ill just wait until my driver comes back sometime next week. I just miss having it, only got a day of use!

EDIT 2: Well while I have everything, might try for some sort of 405nm box build. 6x may be nice, reasonably cheap too.