return to 270 u00b0 when this temperature is reached the voltage on pins 512 and 516 of op amp 506 will be at equilibrium accordingly since the circuit regulates the resistance of hot wire element 44 the output of the circuit on line 518 is proportional to the square root of the power removed from the hot wire times two minus 5 volts for example nominal power dissipated by the hot wire element 44 is one quarter of a watt which is the amount of power needed to keep the hot wire element 44 at 270 u00b0 f any heat removed from the hot wire is replaced by applying more power to element 44 resistance of the hot wire is regulated to 25 ohm thus resistance is considered to be constant power removed equals the power applied minus the amount needed to maintain the hot wire at 270 u00b0 f solving the power formula for voltage v power u00d7 resistance u00bd any increase in power applied to the hot wire element 44 is also applied to the 25 ohm resistor therefore the voltage necessary to compensate for power removed from element 44 is doubled for proper operation of sensor 10 the temperature of hot wire element 44 needs to be maintained at 200 u00b0 f above ambient temperature if the ambient temperature is constant there is no need for temperature correction that is a constant difference in temperature guarantees the same amount of power will be removed from the hot wire element 44 for a given.