found a new host - unsure of batteries.

[ashenfang]

I am looking at using a kobalt flashlight as a new host and also use its stock power supply to drive a red 200mw diode. The flashlight accepts 2 x 3v cr123a lithium batteries. I am using a lm317 driver. Will these batteries drive the laser without any issues?

 

[Benm]

In practice, yes. Its a bit out of spec for the lm317, but most people are succesful in constructig a red laser that runs from 2 lithium cells.

 

[anselm]

That should work fine, the 6V should be enough for the lm3127+red diode.
Even better would be rechargeable Li-ion batteries of the same size, but 3.7V!

If I can run a 445nm diode off 2x18650s, then I suppose a red diode can be run too!

 

[ashenfang]

What do you mean a "bit out of spec"? I believe the cut off voltage for this circuit and diode is around 5.7 volts 4.5v for LD and 1.2v for the circuit. I know 4.5v is not enough as this only starts to light the LD. Is there a point where its too much voltage? Some of the more compact flashlights use 3 x AAA which can be replaced by 3 of the lithium batteries but that would push it close to 12v. Currently the setup is driven by 4 AAA alkalines which does work but the dry cells cant keep up with power demand.

 

[JimBolder]

Yeah, but make sure they're 3.7v rechargables, not 3.0v.

The LM317 linear driver starts acting funny at ~6v and below.