  We show how to exploit instrumentation available in undergraduate student
laboratories to build a simple vectorial bridge. In particular we take
advantage from the possibility to read data from a digital oscilloscope with a
personal computer and describe an algorithm to obtain an accurate evaluation of
the phase difference between two sinusoidal signals. The use of the bridge to
characterize components of a high Q RLC filter is shown to greatly improve the
understanding of results in resonance experiments. Direct evidence of
dielectric losses, of skin currents and of the effect of distributed
capacitance is obtained.
