2.2v 1.2 amp laser driver

[Scci]

I, as well as other people I expect, have bought a pretty affordable 808nm 1 w laser diode.

I need an affordable driver for this and while I think I know exactally how to do it (just by my work in electronics) I dont know much about lasers and would prefer a solid curcit with specs. I dont want to break these diodes. Could anyone help me out? And could I just use a transitor with backwards voltage protection calibrated the same way I do to control pretty much everything else.


Thanks

 

[sinner]

You can use a positive constant current linear voltage regulator like LM317 or LM108x series on pretty much any of the laser diodes as long as your input voltage is atleast 3V above the Vf of the diode,, That's the most reliable yet cheap DIY driver upto date..

http://laserpointerforums.com/f42/diy-homemade-laser-diode-driver-26339.html

A good read, And a great thread till date !!

 

[Cube777]

A LM2941 has a very low voltage dropout, I attached a PDF with loads of drivers you can build yourself (LM2941 is also in there). There is maybe the possibility that you can run it of one Li-Ion cell. :beer:

EDIT: Just checked the datasheet, it has a 0.5V dropout @1A so theoretically you can run the diode of one Li-Ion cell with the LM2941.

 

[Cyparagon]

Just checked the datasheet, it has a 0.5V dropout @1A so theoretically you can run the diode of one Li-Ion cell with the LM2941.

NO! Why does everyone forget about the current sense resistor? The feedback voltage is 1.27V, which means 1.8V dropout if you're operating in constant current mode. Single lithium cell isn't going to work.

 

[Scci]

Thank you very much this is what I expected

 

[Cube777]

NO! Why does everyone forget about the current sense resistor? The feedback voltage is 1.27V, which means 1.8V dropout if you're operating in constant current mode. Single lithium cell isn't going to work.

So you always need to add the dropout voltage plus the reference voltage to get the full dropout voltage when operating in constant current mode? Thank you, I will remember it! :beer:

 

[Scci]

The lm2941 can only suply 1 amp at max, which I guess is close enough, but what is the maximum output volatage because it appears to be only about a volt, which is unacceptable. I doubt that is the case though.

 

[Cube777]

The output voltage is definitely not max 1V, I ran LPC-826 with one of these (Needs around 3.5V)

 

[Scci]

thurso5

ok i realized i miss read the data sheet

How do I calculate what the output voltage/ current will be

nvm found it on another data sheet

I like the on/off pin that adds in a nice override feature

Merged that for you, please don't double/triple/quadruple post.

Ped

 

[Cube777]

Just note that you can edit your posts by clicking the "EDIT" button on the bottom right of your post

 

[Fiddy]

I, as well as other people I expect, have bought a pretty affordable 808nm 1 w laser diode.

I need an affordable driver for this and while I think I know exactally how to do it (just by my work in electronics) I dont know much about lasers and would prefer a solid curcit with specs. I dont want to break these diodes. Could anyone help me out? And could I just use a transitor with backwards voltage protection calibrated the same way I do to control pretty much everything else.


Thanks

You do know that 808nm is practically invisible? which makes it quite dangerous.

Do you have safety glasses for this wavelength? what are you using them for?

Fiddy.