LM317 Driver problems - I can't get the voltage up

[danielbriggs]

Hi,

Ok, this is probably due to my electronics knowledge (or lack of it!)
I've setup a LM317 as per sed diagram

I've got a 50ohm pot and a fixed 10 ohm in together. I'm using 4x 1N4001 diodes in series to simulate the load.

My min voltage is 2.86V @ 20.7mA and when I crank the pot up I get a max voltage of 3.16V @ 120.7mA

Now, as this is for a blu-ray diode, I understand they need around the 4.00V mark, so what I am doing wrong?

I've got 2 meters, the current readings being taken in series with the diodes, and the voltage being taken across the 4 diodes only.
I'm using a 9V PP3 battery.

Also, what generally are the recc. specs for running a DDL blu-ray Current / voltage etc. etc.

Help!


Dan

 

[danielbriggs]

Re: LM317 Driver problems - I can't get the voltag

Edit:

OK, I sat down with a cuppa and read ALL of the DDL's driver post. I had read upto 20 ish a while back, but let it run away.

On page circ. 30, I found the answer!

Voltage will sort itself out to get the current sorted
I have a good range of current, perhaps too high, so I'll swap the fixed 10 ohm for a 20ohm, and I reckon that should give a range of about 15-60mA which is perfect for a blu!

Cheers,


DAn