The scope of this module is to introduce the student to design procedures and the effect of component variations in the behavior of a simple circuit. The student is asked to build an interval timer that produces a 3 second pulse using components provided to them. Also an equation that predicts the pulse width is provided so that the student can check the width for given values of resistance, R, and capacitance, C. Later the student measures the values of the pulse width, resistance and capacitance and compare their values to those of their colleagues. The student explains the causes of variation of time intervals observed. This problem is solved analytically and using a computer method called "Monte Carlo". Finally the student will look at design methods in which appropriate values of R and C can be rapidly determined for a given required time interval.

Lessons that students learn are:

1. Preliminary experimental work
2. Nominal design procedures
3. Effects of component tolerances (Probability Density Functions)
4. Nominal value graph measurements

Each student is supplied with a set of components for construction of an interval timer on a protoboard. Guidelines of How an Interval Timer Works, the Monte Carlo Method and a computer program for designing Interval Timers are all provided to the student to facilitate the completion of the student's assignment.