I have a 200mw laser module that came with a 3v 1A power supply. I want to control it from a digital pin on an arduino uno.

Can I use a simple voltage divider like this or is there some consideration to current I'd need to take into account? The laser module was quite expensive so I'm hesitant to try it out.


simulate this circuit – Schematic created using CircuitLab

  • the arduino is not able to supply the necessary current ... other than that, your question is not related to the arduino, so it is off topic here
    – jsotola
    May 11 at 23:01

Your solution does not work, mainly because GPIOs are not intended to source current higher than a few mA. If you want the laser diode to emit a reasonable amount of power, you need to drive it with a transistor. A MOSFET-based low-side-switch would probably be the easiest solution. But note that you still need to limit the current, e.g. by using a series resistor.

Even better would be to use a constant current driver (you can use any led driver with appropriate rating).

If the power supply that came with the laser diode is a constant current source, it might be possible to switch its output directly (without resistor), but that depends on how it behaves when it is open-circuited.

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