If you are working on a project that responds to sounds, your circuit will require some type of microphone to transduce the sound into a modulated voltage and, most likely, some type of amplification of this modulated voltage. I like to use electret microphones to transduce sound because they require relatively simple circuits. For example,

The following schematic demonstrates a simple infrared (IR) photodiode circuit using a analog-to-digital converter (ADC) to monitor the photodiode. An analog pin on an Arduino used with the analogRead() function will do the job. Photodiodes are two-pin analog devices. This makes them relatively easy to use and makes their output graded. Some of my students

The ATmega328 has a total of three input/output ports, port B, port C, and port D. Two of these ports, namely port B and port D, are associated with the 14 digital input/output pins on the Arduino Uno. Port C is associated with the analog input pins which can also be used as digital input/output

Serial communication is a method for two computers or microcontrollers (or one computer and a microcontroller) to talk to one another. Arduino uses the transistor-transistor logic (TTL) serial protocol. This protocol sends bits using voltages of zero (for a zero bit) and five (for a one bit). Another popular serial protocol is RS-232 which uses

A common-cathode RGB LED has a total of four pins. One of the pins is the cathode which must be connected to ground and the others each control a color. The pinout shown below is for a typical RGB LED. Notice that each of the pins is a slightly different length; the cathode is the