simple L/C meter

With the aid of this device it becomes a simple matter to check the value of capacitors and inductors. When measuring an inductor (switch S2 in position a) the current flowing through the coil is interrupted periodically so that the self-induced voltage can be monitored. This is achieved by feeding one of the six squarewave signals (N1 . . . N6) to the base of transistor T1. The base drive current to T1 is therefore constant in all cases which means that the collector current is also modulated to the same maximum value. The self-induced voltage U can be found from the formula: —LAI At where L = inductance 01 = change in voltage At = time during which the voltage change takes place The self-induced voltage will only alter when a different inductor is placed in the circuit. The average value of the voltage will then be: Uave = L • lc • f where lc = average collector current f = control voltage frequency The average voltage is a measurement of the self-induction. From the propo...