Of course in a video like this there will always be some interesting comments on experienced inventors and novices as well.

commenter pvc998 asks

I wonder why you don’t use ground wire from the PSU. I mean… Red wire is +5V, yellow wire is +12V and black is 0V (ground). Using red and yellow would give you something about 7V (which is what you get) but normally the current is supposed to flow from them to the ground wire and not between them. There are also few more problems with doing that (which I won’t be discussing now).

Is there any particular reason for using red and yellow instead of black and yellow?

another commenter melodic posts

Laser diodes need constant current, so any extra voltage that the driver and laser diode don’t use gets turned into waste heat in the driver. That extra 5V times nearly the half an amp that the circuit is taking puts an extra 2.5W into the driver, which is unnecessary. 7V is enough to power the circuit/laser without causing overheating!

We hope you enjoyed this video and don’t try this at home without the supervision of a professional.  Lasers are cool and can be very dangerous so definitely consult and only work with safety pros when it comes to these types of experiments.