A box containing a receiver, a relay, and a duplex receptacle

This receiver is under a NEMA outlet box which is inside a wooden box. The relay is inside the NEMA box. In addition to controlling this relay, the receiver has separate output signal connected to a 1/4" jack. This was earlier used to control a (defunct) current source for a string of LEDs. It is currently shelved.

This is the circuit board

Here are the circuit diagrams:

Here is the program code.