Suppose you are getting ready to take a physics test. Everything is set—but wait! Your calculator battery died. What do you do? If you're extra crafty, you could grab an LED (light-emitting diode) and ...

One of the questions that hobbyists ask over and over is how to select the value of a current limiting resistor for an LED. Usually the seat of the pants response is: “Subtract 2 V from the supply ...

The project is originally designed as LED calculator but the addition of a rotary encoder to set the target system voltage results to adjusting the LED brightness using the potentiometer. By turning ...