The 16u2 is normally used as the Arduino Uno’s USB interface. The only external hardware needed is a single 120 ohm resistor. The original Apples had cassette and speaker interfaces. So does ...

This is a hotel room door swinging open. The device he holds in his hand is an Arduino connected to the OUTSIDE portion of the door lock. It takes approximately 200 milliseconds from the time an ...

Aside from the Arduino UNO microcontroller, LDR, and the bulb itself, the hardware for this setup is pretty minimal: a relay for the bulb, a resistor for the LDR, and some wires to connect ...