This design showcases much more model complexity and further optimization; it is a simulation of the temperature control of a thermoelectric element (Peltier device) with the aid of an analog PID controller. Going from left to right, there is a temperature-measuring Wheatstone bridge including the sensing NTC thermistor. The variance between the measured signal and the voltage corresponding to the set-temperature profile is amplified, PID-processed, and inverted. It then commands a Darlington transistor pair that establishes a current into the Peltier, drawing the heat out of the body to cool down (called thermal mass). The temperature produced by this function is read by the thermistor, taking account of the delay induced by the response time. The feedback of the circuit design is therefore complete. The next slide shows the temperature waves generated by the simulation.