AC Power supply diode driver help

Hey guys,

Basically I built my first driver a few days ago with my uncles help, and just wanted to check a few things before I hook it up into my diode from a DVD writer.

Basically, in the circuit I have a 35V 47UF capicitor, LM317T, the correct little black diode, 1k multi turn pot (100ohm single turn pot was usless) and 4.7ohm resistor. The twist is, instead of running of a 6V battery, It is running off a  5.3V, 500 mA plug.

I am curious, will a laser diode, bearing in mind that the driver only allows 2.7V to it, only use 200mA of the current, or will it take the entire 500mA and burn out?

Or do I not need to worry about this and will the driver just do it's job? I am a little confused

-Ash

PS: Here is some pictures of the driver:

What laser diode?

Actually it doesn't matter which one you are using....not enough volts I am afraid.

The LM317 needs 3 volts to itself  
Blu ray needs 4.5v so ideal voltage in = 9v
Red laser needs 3.0v so ideal voltage in = 7.2

(with batteries we would usually recommend another volt or so to take care of battery sag)

If you are using a Blu ray be very careful adjusting the 1k pot, the ma will climb exponentialy when you get to the low end, I will post a picture which shows why a 100 ohm is better for this job.

Get some more volts and a test load sorted and you should be good to go

Regards rog8811
[edit]Just noticed you are using a red, you need 6v as an absolute minimum[/edit]

Thanks for the reply,

I am still a little confused though, because I was told that the pot controls the voltage, and was trying to adjust it to 2.75, but with the 100ohm pot it would jump from 0.25V up to 6 and it was impossible to get it in the middle.

well, guess Ill have to have a play or get a schematic of what I have so you guys can understand what I've got a bit better.

I am still a little confused though, because I was told that the pot controls the voltage, and was trying to adjust it to 2.75, but with the 100ohm pot it would jump from 0.25V up to 6 and it was impossible to get it in the middle.

Click to expand...

If you have wired up the LM317 circuit like the tutorials on LPF it is set up for constant current, the voltage takes care of itself and you can ignore it.
How were you testing the output? The driver needs a load to make it work properly, if you were just using a DVM on the output it will tell you nothing.
The first few posts on this thread will tell you all you need to know about testing it:
http://www.laserpointerforums.com/forums/YaBB.pl?num=1197651171

Before you test you need to up the voltage, it will never regulate properly with less than 6v.

Regards rog8811