DVD Burner Laser Driver Help

[Kamildos]

Hi, I want to buy a good and cheap driver for dvd burner diode. Without driver i use 2x 1.5v AA batteries. How voltage i must use with (example) LM317T driver?
Links to buy driver please

 

[Leodahsan]

Without driver your laser diode may suffer damage soon. Don't use it like this (directly drove).

With a LM317, you will need around the Vf of the diode (around 2.6V) plus some voltage for regulation (around 2.5V for the lm317). More than 5.5V should be fine, but you can always find the regulation point, lowering the voltage 'till the laser starts dimming.

If you want to operate with 2*AA, your best bet is a buck/boost driver. The only I can recall right know is the Flexdrive (available at Illumination Supply). Anyways, its kinda expensive for a dvd burner diode (1.5A max, you'll probably run it at 0.4A).

 

[Kamildos]

So i must use min 5,5v - max? 12V? Can i buy ready driver?

 

[Leodahsan]

Maximum voltage is limited by your power dissipation. It depends on diode Vf and set current. If you set 0.4A, and the diode draws 2.5V, at 12v the lm317 would heat:

12v-2.5V * 0.4A = 3.8W. Thats not the maximum, but is plenty for a TO220 IC... Heatsink needed!
IIRC You can go as high as 30V with a 317. But I wouldn't.

 

[Kamildos]

So I use a lower voltage. Can you show me good and simple driver scheme?
How To Build A Burning Red Laser Driver Circuit - YouTube - will be good?

 

[Leodahsan]

This

You can just remove the adjustable resistor, and use 1,25/Resistor value to determine Current out (to the laser diode).

You know resistor associations, right?

If you want 312mA (example), you will need 1,25/x = 312mA, and that will be 4ohms resistor...

Just beware that the resistors, when low value, tend to get hot....