This project started out as a simple control circuit to switch the LED light strip in a Wayfair wardrobe assembly as described in my proposal Wardrobe Light Control.
In the spirit of spring cleaning I had some obsolete Everlight ITR20001T IR sensors and a leftover coil of 4 conductor wire to use for the project.
First thing I did was to print a housing for the sensor. The IR LED is on the right with the clear lens.
Then I added a 4 pin socket housing on the end of the cable (this is a test assembly, so it's intentionally short).
The LED strip that is used for the wardrobe is powered by a 12V adapter, so I adjusted the current limit resistor for the IR LED for 20mA (470 ohms). The IR LED has a max current of 50mA, so there is room to increase it if I need more sensitivity/range. The other two components are a 10K ohm pullup resistor for the phototransistor collector and a diode to allow "or'ing" or the sensors. Any single door open will turn on the LED strip.
I realized as I was wiring the assembly that the Kicad schematic symbol that I am using does not match the pin numbers on sensor datasheet, so I'll need to fix that.
For the switching of the LED power, I'm using an opto-isolated 12V relay. The schematic below is for the 5V version, but it is functionally the same with some component value changes.
The completed test assembly is shown below with barrel connectors to allow it to be inserted between the power adapter and the LED strip.
Here is a short video showing the circuit operation with the proximity of a box emulating the opening and closing of a door.
Unfortunately, I was not able to complete this project as planned because we ran into problems with the physical wardrobe unit itself during assembly. This is a unit that Wayfair sells that is manufactured in China and the metal doors on the unit are very poor quality. We were having a difficult time adjusting the doors to fit properly and I realized that the sheet metal where the hinges are mounted was so flimsy that it was actually deforming with just the normal opening and closing of the doors.
My son decided that he wanted to make these units work, so that is what we are doing (I am reinforcing the area with a mending plate) - but that effort has made it impossible to complete project as I wanted.
I've also decided that I'd really like to add remote control to the project, so that he can control it with the Google Home controller that he uses for the rest of lights and blinds.
But that might be something for the next Project14 competition 
. Happy Spring Cleaning!