Opto Isolator (6n137)
An optically isolated input circuit to provide input protection for an Arduino using the 6n137 fast optocoupler.
Detailed instructions are included in the Fritzing file along with design details and calculations. This opto isolator (opto coupler) is designed to tolerate a wide range of inputs and could be used as the front end for a dcc decoder. The 6n137 is chosen because of its fast speed, high voltage slew and short rise time.
The 6n137 part is included in the design.
Schematic is complete, PCB and breadboard not laid out.