Stereo Audio Switch Controlled Via LAN

This project illustrates a LAN using a web browser to control an Arduino-based stereo audio switch.

In the design, a 5V DPDT relay is used along with an Ethernet-capable Arduino and a few 3.5mm stereo sockets to produce a simple audio switch that would permit switching one audio source to one of two outputs through a web interface running on the Arduino. The Arduino is also equipped with an Atmega168 or 328. The calculation of how much current the relay would need is required in order to determine whether the Arduino could supply current to power the relay and whether the transistor can perform the job of switching a sufficient amount of current. The BC337 NPN transistor was chosen for the switching of much current.

Connected in parallel across the relay coil is the 1N4001 diode which is used to protect the Arduino and transistor from brief high voltage spikes when the relay is activated and de-activated. The left and right channel pins of the audio input connector are both connected to the two pins nearest the coil. The grounds used for power and audio input/output must be separated in this project.

Rest of the project