Problems with LM317 driver

Hello,

today I built LM317 LD driver. http://www.rog8811.com/LM317%20components01.jpg?0.35312663627278806. Problem is that when I turn on, resistors are on 5 Ohms, voltage between LD+ LD- is almost the same like power supply. Power supply ~7.6V (not fully charged). I added test load, Turned POT till LD +- voltage became 2.9V, but current now is only 20mA. Here is something wrong or it's ok? My LD need max 3v and 340mA

You have the LM317 set up in a current regulation configuration. Adjust the potentiometer until you get 340mA and do not worry about the voltage.

Do not worry about voltage? This won't fry my voltage? Because I'm scared of wasting my money again ang burning the LD.

The driver is set up as "constant Current" - current is the fixed variable.
The driver will automatically 'adjust' the voltage (as the resistance of the diode changed due to temp) and drive the diode at your desired current.
Ohms law.

ATB
MM

How do I test if it is working good without LD and test load? I ordered LPC-836 LD, max safe current 340mA. Aixiz module will be enough for heatsinking or not?

Answer #1: You buy or build a test-load and properly measure how much current is going through your driver using a multimeter. You're just asking to have your laser diode fried otherwise. Alternatively, you can measure the current passing through the current regulating on your LM317 driver.

Answer #2: No it is not. Buy or create a real heatsink. I've fried many red laser diodes because I didn't use a heatsink, saw the pretty red laser light, left it on too long, and burned out $20 worth of laser diode in a few seconds.

If you're afraid of burning out your laser diode again, you need to do it right and not take any shortcuts.

z4ibas said:

How do I test if it is working good without LD and test load? I ordered LPC-836 LD, max safe current 340mA. Aixiz module will be enough for heatsinking or not?

Click to expand...

If you don't want to buy an endless supply of replacement
Laser Diodes then I would also suggest buying or building
or borrowing a LASER DRIVER TEST LOAD...

The heatsinking has also been answered...


Jerry

You can contact us at any time on our Website: J.BAUER Electronics

I have not Aixiz but almost the same module Focusable Laser Module Host 5 6mm Laser Diode Case w H Lens DIY Laser Host 1pcs | eBay . If I put those 4 parts from left, into big heatsink, it will be good?

z4ibas said:

I have not Aixiz but almost the same module Focusable Laser Module Host 5 6mm Laser Diode Case w H Lens DIY Laser Host 1pcs | eBay . If I put those 4 parts from left, into big heatsink, it will be good?

Click to expand...

Yes...


Jerry

You can contact us at any time on our Website: J.BAUER Electronics