I want to run a laser diode from a battery with a minimal setup.

Suppose that I add a capacitor in parallel with the laser diode as to prevent any voltage spikes and a series resistor as to limit the current flowing through the LD (taking into account the maximum input voltage).

What problems could be expected from such setup? Would adding a fan make a difference?

It would not really matter if the input voltage causes the LD to lower its light intensity as battery drains.


1 Answer 1


What you have described works. If there is no inductance being connected or disconnected to the battery, capacitor is not needed. R = V / I. Find the maximum current, the battery maximum voltage, calculate the resistor, calculate the power rating of the resistor. The LED converts the electrical energy to light and heat. Cooling it with a fan would help,

  • 1
    \$\begingroup\$ Could heat cause the values to change and put the diode in danger? \$\endgroup\$
    – JuanΠ
    Jan 9, 2015 at 23:58

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