IR Sonic Screwdriver - IR LED Low Voltage when Transistor Driven

Other Hardware LEDs and Multiplexing
11

Octavas:
If that's the case do I have the transistor wired up correctly?

And how could I get the current higher such as 40mA to 90mA like i'd hoped?

  1. Yes.

  2. Lower the resistor value.
    You know that ~1.5volt drops across the LED+transistor.
    So ~3.5volt across the resistor if the supply is 5volt (and not sagging).
    R = V / I = 3.5volt / 0.09Amp = ~39ohm for 90mA LED current.

For two LEDs in series, ~3volt will be across LEDs+transistor.
So 2volt across the CL resistor.
2/0.09= 22ohm for ~90mA LED current.
Leo..