This a 4 circuit version of the Enhanced Optical Position Detector, contributed by John Plocher and based on Geoff Bunza's DAPD.  It has 4 independent optical detectors for high density applications.  4 Circuit Enhanced Optical Position Detector uses an Arduino ProMini (included) for its timing and de-bouncing, so these parameters can be changed in software.

The EOPDx4 uses Geoff's self-calibrating detection circuit, so you don't need to adjust for ambient light level.  Note the circuit won't work in the dark unless you substitute infrared Photo transistors and provide an infrared illumination source.  The supply voltage range is 5 volts and the The output is an open drain (2N7002) which can sink up to 115mA @ up to 48V. 

 Either 4 sets of 2 PT-19 photo transistors or 4 of “Da Fingah” are provided (we can mix and match, send us a message with the order), a reference detector and another to be placed between the rails. 2 24" double ended connectors are supplied, cut them in half as desired and make your sensor connections.

4xEOPD preliminary instructions

4xEOPD Schematic

4xEOPD Board Layout

4xEOPD Bill of Materials

4xEOPD CAD Files (Gerbers)

4xEOPD Arduino Sketch

The EOPD is a compatible Modular Signaling System (MSS) Optical Detector