Build My First Laser, Quick Question.

I just finished my first laser the other day and I have a question about the negative connection from the battery to the driver. I couldn't tell where to put the negative so I just made a little coil of bare wire (which contacts the battery) and soldered it to a straight piece of wire up along the batteries to the driver. Where does the negative from battery to driver usually go?

If you build your laser into a flashlight host or any other "enclosure" then this housing acts as the negative connection. A spring at the tailcap usually connects the (-) from the batteries to the housing. And the (-) of your driver is connected to the housing or shares a common (-) with the laser diode.

A spring does contact the battery in the tailcap, but to me it didn't look like the aluminum was bare enough to connect properly to the flashlight body. Also inside the body up where the driver is, the aluminum is all anodized, I don't think it can make an electrical connection there.

You would like to ensure that there is some bare aluminum there to make contact from tailcap to body and from body to driver. If not, then simply take a piece of sand paper and grind the anodizing off. In case you have a DMM, set it to resistance mode and check the conductivity of your connections.

Yes, I have a meter. If I sand down the aluminum to get rid of the anodizing, would I be able to solder wire to it? I'll be late answering as I have to go help bale hay so I don't when I will be back.

No, soldering to aluminum will be very difficult using a normal soldering iron. What I did once was I wedged the bare (-) wire from the driver in between the pill and the body of the host. Before you tighten it simply stick the wire in between and tighten it down fully. Know what I mean? Look at pic #6 from the top in my build report here. There you can see the blue (-) wire wedged in between the pill and the body. Depending on your host, you could use the same method.

I think I could do that on mine too. I'll look at it tomorrow.