a litte help for a begineer please!!

daniloxx · Jan 27, 2011

hello, i need to learn how to set up my driver current and how to perform a test-load, i was reading and i understood that i need to set up the current using a potentiometer, and the test-load i perform while setting up the current, getting some reading from the multimeter. Is it right?

if it is not, please correct me, i can´t wait to create my first laser

(i am trying to build a handheld pointer using these parts:

hotlight kit - http://laserpointerforums.com/f64/mohrenbergs-laser-emporium-58611.html

20x lpc-815 diode - http://modwerx.com/shop/lpc815-20x-dvd-burner-laser-lens-assembly-w-red-laser-diode-p-2.html

Laser focusing module (5,6mm diode) - http://modwerx.com/shop/laser-focusing-module-for-56mm-laser-diodes-adjustable-focus-p-11.html

coated glass lens for laser focusing module - http://modwerx.com/shop/ar-coated-glass-lens-for-laser-focusing-modulesred635670nm-p-37.html

Adjustable laser diode driver circuit (assembled) Red - http://modwerx.com/shop/adjustable-laser-diode-driver-circuitassembledred-or-bluray-p-8.html

will it work? wich current i must adjust the driver for this diode? Wich batteries are the best for this project?)

thank you for any help!!!

Coherent Light · Jan 27, 2011

You need to either Build or Buy a test load to set the current out of the driver. The purpose of a test load is to simulate the Laser Diode so You can set the current without damaging the LD.

daniloxx · Jan 28, 2011

to build that test load i need to know the voltage drop of the lpc-815 then i need to get some 1n4001 diodes and connect them in series (use as many as needed to reach the lpc815 voltage drop to simulate it), and in the end of that serie i connect a 1 ohm resistor. This is how to build the test load? If it´s right, how i make the connections between the batteries, the diodes+resistor, the switch and the driver?

i read in someone´s thread that you are running an lpc-815 diode on 400-450ma if not mistaken, and it is working fine for some months yet. How i set up my driver to run the current in like 400ma ? I do it using a potentiometer (thats what i understood from the guide)? If it is using the potentiometer, how i choose the right one? Because when i search one for buying they are listed with something like 100k, 500k, what that means? Which is the best one for my situation?

Thanks again

Coherent Light · Jan 28, 2011

If it were Me I would just crank the driver to the Max since the highest output of the Driver you linked to is ~430ma. But that's Me YMMV.

AUTO XX · Jan 28, 2011

If you can turn the laser on when you are adjusting it is easier, sometimes the pot doesn't work right at the extremes.

daniloxx · Jan 29, 2011

Coherent, there is another way to put the driver to the max without use the potentiometer? If not, how i put it to the max then?

Auto XX, how can i adjust the current with the laser on? isn't this dangerous for the diode? How would i know the current being sent to the diode?

What you mean that the pot doesn't work fine at the extremes?

And what the 100k, 500k, etc means when buying the potentiometer?

ty

Coherent Light · Jan 29, 2011

I think what Auto is suggesting is that since the driver won't put out enough current to blow your diode is for you to hook everything up and turn the pot till the diode is the brightest. Short the driver before hooking up the diode.

You can replace the pot with a fixed resistor to get maximum power out.

daniloxx · Jan 29, 2011

sorry, i didn't undestood what you meant when said to short the driver.
And replace the pot for how much Ohms resistor?

And what is that 100k, 500k... potentiometer?? xD i need to buy one, but i don´t know wich one.

thats the last thing i need to know and wont bother you anymore xD (not offense)

Thanks a lot for your help man!!!!

Coherent Light · Jan 29, 2011

You need to touch the + & - on the output of the driver together to discharge the cap. If you have wires soldered on just touch them, and if not use a piece of wire or another metal object to both pads on the driver. To use a fixed resistor you would have to remove to pot and replace it with a set value which would have to be calculated. It's easier to use the pot unless you are very good at de-soldering small parts.

daniloxx · Jan 29, 2011

so i touch the + - of the driver, then i solder all the parts and turn on the laser, i rotate the pot until the light is brightest right? do i need to take of the potentiometer after that or leave it soldered there? because if i leave soldered i don't think it will fit the host later....

Coherent Light · Jan 29, 2011

I think that driver will just fit inside an AixiZ module, but you should see if it will slip inside before continuing. No you can't remove the pot after you set it, because it's what sets the current. Clockwise increases current, so after you short out the pads you can solder you diode or solder the diode to the wires (if any). If this driver won't fit into the module you will have to use wires, and mount the driver somewhere on the host. You will need to put heat shrink on the wires at the diode pins if you solder wires on.

daniloxx · Jan 29, 2011

ok, i think its fully understood now, this laser will be potentially dangerous for eyes right? if i want to make it weaker after it is complete, to play with my pet (for exmple) inside my home, like i do with those 0.50$ lasers for kids, i can rotate the pot again counterclockwise until it become just a little harmless dot for this kind of use? or making this a couple of times will harm the diode?
I asking that because my girlfriend like lasers too, how they can burn things, the long distances they reach and all the applications they have, but she don't care about the eye safety, she thinks it's just "bullshit", if that's not possible i will have to hide those lasers i will build...

thanks man, you really helped me a lot!!! if i have any questions i post again...

daniloxx · Jan 29, 2011

even if i tell her that they are dangerous, probably she will get and burn something for fun while i'm not home and will get hurt just looking to the powerful dot light.

Coherent Light · Jan 29, 2011

Yes you will have to be careful with this laser, and you need to get some laser safety glasses. You really don't want to be opening it up and turning the power up & down, because eventually something will break doing this. Get a cheap 1mW pointer for the pets and leave the high powered one alone when safety cannot be assured.

Even at lasing threshold this laser will be too powerful to play with your pets and kids!!!!!!

I estimate that at threshold it could output 60mW....NOT SAFE

daniloxx · Jan 29, 2011

yeah, i think thats the best solution...
Don´t worry, the glasses were my first step into this hobby

i love my eyes, they are really useful these days xD... Thanks again, and see ya

AUTO XX · Jan 29, 2011

Well said Coherent!
If your girlfriend thinks that it is bull$#!T show her how it burns and then ask her what the hell she thinks it would do to an eyeball.
Burning something always shuts people up about me harping on safety around here

Most pots have a rated "duty cycle" they can only be turned up and down a few times (flexdrive pot is rated for 15 adjustments, microboost is more robust)
When you are playing with the power settings remember, you still need to get the heat away from the diode, at least a module for short runtimes and a full heatsink for anything longer than I guess about 15 seconds at ~350mW

a litte help for a begineer please!!

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