How to run 50 IR LEDs off an Arduino UNO?
You should put a current-limiting resistor in series with each LED.
You could then try to drive all of those LEDs from a beefy transistor, like
a power MOSFET or a Darlington. Alternatively, you can use a small
transistor for each LED, and then drive all of them from a PNP transistor,
like this:







simulate this circuit &ndash; Schematic created using CircuitLab

This way, if you want to drive some of the LEDs independently, you can just
connect an Arduino pin to its R2.

Beware that the PNP reverses the logic: pin LOW turns the LEDs ON.