Frickin’ lasers

I purchased a quantity of cheap laser modules for a project.  They were advertised as 3V modules, but they all have 39Ω resistors in series for current limiting.  When connected to two AAA batteries, I measured 15mA and a forward voltage of 2.15V.  This makes the resistor value 0.85V/15mA=57Ω though.

laser_module_1laser_module_3laser_module_2

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