My 6 hour build. Any thoughts?

[mikeh918]

This is my first post on LPF and my first laser in general, so sorry if I sound like a noob.

I decided yesterday i wanted to build a burning laser after i came across one on one of my electronic hack forums(too much free time). So i did a decent amount of searching on what I would need to do and just went with it.

I had a broken laser projector I took apart to see if I could salvage any parts and found the housing/heatsink for the diode, popped out the old diode and ordered an lpc826 660nm diode to replace it. Will this work? Or would i need the Aixis module?

I also through together an Lm317 driver. I put a heatsink on the Lm317 and plan to add a fan to the host I'm making out of an old enclosure I had laying around.

My real question is, in order to achieve the optimal(yet still reliable) power of the diode, how do I need to set up the driver? The diode has a 300-400mw rating, do I need to stay between 300-400mw to get it to burn? Will the two 10ohm resistors create the right amount of current? What batteries should I use?

Any input or advise would be great! I'm going to continue reading up information, I also ordered safely goggles, and I will make any necessary changes before I put it all together.

 

[mikeh918]

is 660nm different from the 658? or is it just rounded up?

 

[Eudaimonium]

Just rounded.

Looks good. Well done, clean, professional. Heatsinked appropriately.

Note, you don't really need a potentiometer. Just follow this next time:

 

[norbyx]

It looks very nice to me. Very nice heat sink indeed.

 

[mikeh918]

Just rounded.

Looks good. Well done, clean, professional. Heatsinked appropriately.

Note, you don't really need a potentiometer. Just follow this next time:

how much current should I be using for the lpc826?

 

[Eudaimonium]

0.4 Amps max, so that's 400mA.

Always input the current in Amps, not miliAmps in the equations.

 

[mikeh918]

0.4 Amps max, so that's 400mA.

Always input the current in Amps, not miliAmps in the equations.

So if I currently have two 10ohm resistors in parallel giving me 5 ohms, divided by 1.25 which gives me 250ma... The potentiometer would raise or lower the current?

1.25 is regulated voltage out of the lm317?

Should I switch the resistors to get 3.2 ohms?

Does anyone know the minimal current it takes to burn with this diode?

Sorry for all the simple questions, I'm still fairly new to electronics

 

[Eudaimonium]

So if I currently have two 10ohm resistors in parallel giving me 5 ohms, divided by 1.25 which gives me 250ma... The potentiometer would raise or lower the current?

1.25 is regulated voltage out of the lm317?

Should I switch the resistors to get 3.2 ohms?

Does anyone know the minimal current it takes to burn with this diode?

Sorry for all the simple questions, I'm still fairly new to electronics

Pot is lowering the current. I don't know where that old schematic with 2x resistors in parallel and potentiometer originally came from but it cost me a lot of diodes. It'd be infinitely easier to just use a single fixed resistor, calculated to fit your setup.

1.25V is the reference voltage used between LM's "OUT" and "ADJ" pins. Use that to calculate resistance needed, to achieve your needed current output.

Minimal current to burn? No idea, at around 200mA it should output some what, 100mW? That should be enough to light a match.

 

[mikeh918]

I would like to get the most life out of the diode, so I may take out the pot and leave the two parallel 10ohm resistors to run 250ma if it should still burn

 

[Eudaimonium]

It should, 250mA is quite conservative, and will net you some nice output power.

It's probably what you're running right now if your potentiometer is at minimum value.