driver question

[Bratzi]

Hi!

I have a little question about my driver. I bought a A140 445nm 1W diode and now i need a driver for it, which i want to build myself. I saw this driver circuit online and i found all the parts for it online to order.

I used a LM317 regulator and according to the online calculator, i need a 1,8 Ohm resistance for 700mA.

What do u think about this driver? will the LD handle the 700mA? And i saw circuits with a trimmer resistance. would you recommend them? or if you have a similar diode, what driver do u use?

I'm sorry that the picture looks like instagram-filtered. It's not. Thats a disease of my HTC One camera.

By the way i'm german, so please don't hate me if i made some mistakes.

 

[bobhaha]

700mA is a safe level for your diode.

The LM317 driver will consume some voltage... so you must make sure your supply voltage is atleast 1.5V above the forward voltage value of the diode.

 

[Cyparagon]

No, you need absolute minimum of 3.5V over the load voltage. The regulator itself needs >2.25V, and the shunt needs 1.25V. In this case, 9V is ideal. 12V will work, but will create more heat. Also be sure to add a heat sink to your regulator.

Trimming the current isn't necessary for most cases. Your calculations are correct.

 

[Bratzi]

Ok, thanks for the replies.

I plan to connect 3 3,7V 3600mAh Li-ion batterys, so i have 11,1V


To test the driver, i want to use a test load. i saw some, but i am not sure which design to use.

keep in mind, i use a A140 1W 445nm diode. Is the test load (picture below) suitable?

6x 1N4001 Diodes and 1x 1 Ohm Resistor

 

[Cyparagon]

A test load isn't necessary. If your current set resistor is 1.8ohm, you'll get your 700mA. If you still insist on using one, decrease your diode count to 4.