Quote Originally Posted by Smiler View Post
Bill,

You have no idea how much I envy you and the others knowledge of electronics. I'm afraid I have a "nuts and bolts" brain and electrickery will always remain a dark art.

Thanks very much for the help guys, I'm off to find an 1N4001 and wire it in series.

Jeff.
Don't forget to wire it the right way round else your laser won't turn on! The diode casing has a white line at one end, this end needs to be more negative than the other (i.e. points to the -ve end of the supply) for current to flow.

Bill's solution is the simplest and easiest to get a 0.7v drop at up to 1A (for an 1N4001 diode, although any of the 1N400x range will do). If you need more than 1A then 1N5059 series is good for 2A and 1N5624 series for 3A.