Changing the Opto EndStop for Prusa/GRBL to Allow 5V signals
Having built the version 7 Opto Endstop that is the RAMPS standard for Prusa and other RepRaps I recommend a slight change to the circuit.
The official circuit is:
You could go with a 100 ohm resistor instead of 180 ohm.
Sub note, the only difference between the Vishay TCST 1103 and the Vishay TCST 2103 is that the latter has an extra plastic flange to make mounting easier. The actual electronics are the same: