Capacitance and Inductance Sensor Circuits for Detecting the Lengths of Open- and Short-Circuited Wires

The length of an open- or short-circuited wire is linearly proportional to the capacitance or inductance of the wire, respectively. Several types of simple and inexpensive circuits are introduced to measure these values. Open-circuited (capacitance) measurements are very effective. Short-circuited (inductance) measurements are more difficult, and not all of the circuits worked well. A 555 timer circuit was found to have the best overall performance to locate the ends of both open- and short-circuited wires. The capacitance and inductance values of various types of aircraft wires were measured and verified with analytical equations.