Where 10 pF capacitor with power line stub is coming down should be 1838T Infrared Receiver. Bottom 26.6 uS Square Wave generator is IR remote control pointed at 1838T receiver. LED on left shows visually if remote is working. Drawing showed 1 K ohm resistor but 100 ohm made the simulator work.
Signal from this circuit can be input to oscilloscope to check IR pulse codes.
