555 WatchDog

16x12mm module based on 555 timer
Intended to reset the MCU via RST pin if not "kicked" periodically.

This is a work in progress.
The schematic is yet to be validated

Comments and improvements are welcome.
I would appreciate if someone knows how to run a simulation to validate this.
Another open question - how does this work with 3.3V kick from ESP8266.

To preempt the question: yes ESP8266 does have a watchdog. This is a hardware approach that I would feel more comfotable with. No effort will be made to force anyone to use it instead of the built-in software approach.