TL;DR
Stephen Woodward created a simple thermostat using the classic 555 timer integrated circuit (IC). Instead of employing a complex PID (Proportional-Integral-Derivative) controller, he opted for a straightforward bang-bang control method. The design incorporates a thermistor for temperature measurement and some clever tricks, like using the threshold pin to turn the trigger pin into an inverting analog comparator. This approach allows for a basic yet effective temperature control system.