Example: circuit determines the LED has a forward voltage of 1.8v and you have 99v, 10mA set, it will do this: 99v-1.8v/0.01A and come up with 9720 ohms resistor. (10k would be the nearest common ...

Inside the cool laser-cut box is an Arduino Uno and a 9V battery, plus a current-limiting resistor and the all-important buzzer. ... 4 thoughts on “ 1D LED PONG, Arduino-Style ” Joshua says: ...