Sometimes the most useful hacks are also the simplest ones. A case in point is the LED and resistor assembly that [Skippy] recently posted on his blog. The idea is to solder up some pre-made ...

The circuit in question ... A transistor is also wired up, switching a 2.2 K resistor in parallel with the LEDs. When turned on by the PIC, this transistor causes roughly a 10 mA current to ...

Using properties of a series circuit, the sum of the voltages across the LED and resistor R must equal the supply voltage. \({V_s} = {V_{LED}} + {V_R}\) Now substitute the supply voltage (\(6V ...