The amount of time needed for a sensor and associated circuitry to respond to a change in condition. This time constant is one of the items used in optimizing the design elements of a sensor. In most of our legacy sensors, 0.1 seconds is the typical value and in modern sensors 0.01 is the typical value. If we abbreviate the response time constant as “t” then a full step change in input signal will change the output to 63% of its final value in t seconds, and will settle to within 1% of the final value in 5*t seconds, 0.1% of the final value in 7*t seconds, and 0.01% of the final value in 9*t seconds. In addition, a step change in input signal will change from 10% to 90% of its starting and ending values in 2.2*t seconds.