DDL Test Load

Well, I built the test load circuit for the DDL driver using 4 IN4001 diodes and a 1 ohm resistor.
When I test the voltage with my DMM I am getting about 5.6 volts. When I try to measure the
mV across the resistor I don't get a reading at all. Any ideas what I am doing wrong? I have
rechecked all my schematics and near as I can tell the driver and test load are wired correctly.
Interesting thing is, if I connect a plain green LED to the circuit I can adjust the brightness from
very bright to almost off on the LED by turning the pot. I just want to make sure I don't blow my
DVD LD when I connect it to the driver. Any advice would be great.

Thanks

Okay, sorry for the premature post.  :

I figured it out. Newb as I am I had all 4 diodes backwards in my test load circuit. [smiley=embarassed.gif]
It is now working correctly and my driver is working great.

Only one question remains. How many mA should I drive my 18x open can LD at?
I don't want to overdrive it as I would like it to last for a while.

Thanks

[highlight]EDIT:[/highlight] I did some searching and found that it should be safe to run a 16x diode at 150mA.
My diode being an 18x open-can I figured the same would apply to it. I set my driver for 150mA and connected my
diode. It is working great! The question is how much further can I push it without stressing the LD? Can anyone suggest
an optimal current for an 18x diode to provide good power and long life?

I'm thinking 250mA, up to 300mA......................

Cool! Thanks!
I might try going up gradually just to see the difference from 150mA
to 200mA then maybe 250mA. Now I need to look for a conversion
formula/chart to see how many mW it is puting out. ;D

Here you go!
http://www.laserpointerforums.com/forums/YaBB.pl?num=1210649510
Jay

Hey, thanks a bunch for the link. That helps alot!

Now I just need to get a new battery box to power
my laser. I was using a 4-AA box with alkaline batteries,
then I read that they drop off quickly and can actually cause
a spike that kills the diode. Is this right? Now I am afraid to
use the alkaline batteries. I have 6 NiMH AAs but I just need
to get a battery holder for them. Guess my project is on hold
until I get in to Radio Shack.

Okay, I got my battery box all set up. I am running 6 1.2V NiMH AA batteries.
I connected my test load circuit to my DDL driver and set the current to 200mA.
At that current I am reading 3.3V. Is that voltage too high? I really don't want to
blow my diode.

The interesting thing is that when I first hit my switch I get about 3.5V and it gradually
settles down to 3.3V constant. I checked the reference voltage on my LM317T and it is
1.23V. I also checked the voltage coming off my batteries and I am getting 8.0V so that
may be where I am getting the higher voltage to the test load. Also my LM317T seems to
be getting quite warm, granted I left the circuit on for awhile. Should it be getting warm at
all taking 8V?