The assembly of a Lock-In d igital Amplifier (LI d A) from widely accessible ready-made modules is
presented. This equipment, which does not require any advanced knowledge of electronics or
programming, may introduce the experimenter to resonant techniques by registering mechanical
resonances. The freely available control program allows for general data acquisition and further
data processing. The apparatus is versatile and may corroborate the science and engineering
laboratory in elasticity measurements or in a series of experiments where a modulated signal is a
prerequisite.