The TCUT1800X01, Vishay opto’s 4 channel optical transmissive sensor, is a unique part in that it allows the encoding of 2^4= 16 absolute positions. This makes it perfect for many applications such as the temperature control in a car, with each set position denoting a given temperature.
However, what happens when as a designer these 16 positions are not enough, as you have more temperature increments that need to be set? Also, what if you don’t have the full 360° of rotation of a code wheel to your disposal as you don’t want the end user to have to rotate all the way around just to reach the final set temperature?
Rest assured that this does not mean you need to throw your TCUT1800X01 followed by your entire design overboard!
As is often the case with Opto, there is a solution!
By adding another TCPT1350X01 to your design, a tried and tested single channel tramsmissive sensor, and giving your encoder wheel another “track” of information , you can easily implement say 22 positions in a robust and repeatable manner.
Taking these required 22 positions as a typical example , the Vishay application note “Encoding and Code Wheel Proposal for TCUT1800X01” now has an added appendix that covers the design considerations and “gotchas” that one encounters in such a design implementation, giving an example of a code wheel pattern that would lead to the desired result. There’s even a description of 3D model that is 3D printable!