Rather than speculate how the unit purchased was intended to operate, why not design and modify the unit the way you want it to work.
1) Establish which is the emitter and which is the sensor.
2) Select R1, R2, and trim RV1 for desired sensitivity.
3) Accept the logic output as given and design output driver transistor for desired operation.
1) Establish which is the emitter and which is the sensor.
2) Select R1, R2, and trim RV1 for desired sensitivity.
3) Accept the logic output as given and design output driver transistor for desired operation.