red diode voltage question

[MISTERWILLING]

I am confused on what voltage to run my 22x red dvd diodes i got from daedal. i hooked one up to my homemade driver at 6v and 200mA and barely got any light out of it. so i tried a 9v and then all i could get the driver to push was 125mA, but then the diode was very bright and measured 100mA on my laser bee. I thought the red diode were supposed to run at like 4v according to what i have seen posted here. Also i purchased some drivers from DX that are AMC7135 350mA (havnt arrived yet) which recommend 3.5-4.5v input, if i have to run those at higher voltage to get my laser to be bright, what will that do to the drivers.

 

[pseudolobster]

What driver are you using?

All the drivers we use around here output a fixed current (amperage, measured in mA), and the voltage is automatically adjusted to get the right current. The laser diode should be pulling ~3v or so, depending on the current, but really you shouldn't have to worry about the output voltage, the driver takes care of that for you. You do have to make sure you get the right range of input voltage though, depending on which driver you're using you might not be providing enough voltage to start with...

If you're using a LM317T-based driver (aka the DDL driver), or the rkcstr "micro adjustable driver" you'll need to provide at least 2.5v above the voltage needed by the diode, so at least 6v. The rkcstr driver is capable of as high as a 12v input, most DDL drivers are capable of handling as much as 15v input. If on the other hand, you're using a drlava flexdrive, this is a boost driver, meaning it's capable of putting out more voltage than you feed into it, so it can happily drive a red diode as low as 2.5v, though don't feed it more than 6v.

 

[MISTERWILLING]

I am using a DDL driver, but it was my first one and it is badly soildered and arranged, maybe that is why i am having trouble with it. I will rebuild one with better construction to see if that fixes my problem, i shouldnt have to be putting in 9v to supply my red diode, my driver may be losing voltage. What current range should the DDL driver go up to? Hooked up to a 9v i can get 80mA max and when i bypass the resistor in the circut i get 125mA max, is this what it should be outputting? I need like 150mA for my PHR diodes and like 350mA for my DVD diodes.

 

[XCreedX]

Hmm, i built my labby with a LOC @ 400mA with 12v, Use a 3 ohm resistor that should give you about that

 

[MISTERWILLING]

LOC = ? ... And a 3 ohm resistor where, please be more specific as I don't know much about circuts and electrical components.

 

[pseudolobster]

LOC = Long Open Can (the diode found in 20x and 22x DVD burners)

Most people run them at around 420mA, which if I recall correctly is somewhere around 2.5ohms... I think a 3ohm resistor will give you just under 400mA.

A DDL driver is capable of delivering as much as 1500mA depending on your choice of resistors/potentiometers, so if you're only getting 150mA out of it, there's a problem somewhere.

 

[MISTERWILLING]

Thank you for that info, I will rebuild a DDL driver and see what happens.

 

[hydrogenman15]

If your using the LM317T driver the reference voltage is 1.25. So 1.25 divided by .42 amps is
2.97619 ohms. So you can use a 3 ohm resistor to get 420 ma's.