Red Laser, x16 DVD burner... etc

Hello! I'm new here; But I have a great understanding of electronics.

https://docs.google.com/viewer?url=http://www.fairchildsemi.com/ds/KA/KA431.pdf&embedded=true

This, would make a really nice low drop out cc regulator, correct? The only issue I could see would be that it can only push 100 mA! SO, I could just add an external pass transistor (say, 2N3904?) and it would make a really easy small CC linear driver for laser diodes.
Any thoughts?



As far as my project goes, I took apart a dvd burner from an old laptop that was well, in pieces. I got the burner diode successfully out of the aluminum can, and noticed that it's one of those open air diodes...

Using an LM317 as a CC source, with around 250 mA of driving current it lases pretty brightly. I have to use a 9 volt battery, though, which is why I'm thinking about using the shunt regulator I talked about previously so I can use 4.5 volts a la 3 AAA batteries. Does 250 mA sound about right for driving this kind of diode? I still need to get a case for the diode itself. Right now I'm using a pair of tweezers as a heatsink for test runs, and an old lens from a cat toy laser pointer.

I'll post pictures probably tomorrow.

Hey,

Not sure about your regulator question but 100mA is pretty small value around here
The LM317 are the easiest to make, and there a many pre-made drivers you can purchase too.

Your so called 'open air diodes' have a name here in depending on its size.

You will have a LOC (Long Open Can) or a SOC (Short Open Can) dending on how tall the diode is.

Its really hard to judge current if you don't know the model of diode or burner you retrieved it from, the lowest powered Open Can diodes can handle about 300mA anything under that is good to, just make sure you have adequate heat-sinking!

It is not a good idea to run the diode in open air at that current, you may very well reduce the life of your diode. A simple way to do test runs is to get a old alloy heatsink and drill a hole in it the same size as the diodes base and press it into the heatsink.

Fiddy said:

Hey,

Not sure about your regulator question but 100mA is pretty small value around here
The LM317 are the easiest to make, and there a many pre-made drivers you can purchase too.

Your so called 'open air diodes' have a name here in depending on its size.

You will have a LOC (Long Open Can) or a SOC (Short Open Can) dending on how tall the diode is.

Its really hard to judge current if you don't know the model of diode or burner you retrieved it from, the lowest powered Open Can diodes can handle about 300mA anything under that is good to, just make sure you have adequate heat-sinking!

It is not a good idea to run the diode in open air at that current, you may very well reduce the life of your diode. A simple way to do test runs is to get a old alloy heatsink and drill a hole in it the same size as the diodes base and press it into the heatsink.

Click to expand...

Well, it so turns out that my diode is NOT a TO-18 can.... I.E. not 5.6 mm.

I measured it to be 4 mm on the spot. It can burn stuff when I focus it really well with the lens from another CD drive I took apart earlier today.

Hopefully my friend can drill me a heatsink sometime.

Ahh yes, they are classed as a 3.8mm diode, there are no modules available for the 3.8mm diodes atm.