  We present an easily reproducible, open-source, sound card based experimental
set-up to support transfer function measurement. Our system is able to
visualize signals of mechanical and electrical resonances and their spectra in
real time. We give a brief description of the system, and show some examples of
electrical and mechanical resonance experiments that are supported by the
system. The theoretical background, experimental set-up, component selection
and digital signal processing are all discussed, and more detailed information
(building instructions, software download) is provided on a dedicated web page
(http://www.noise.inf.u-szeged.hu/edudev/RealTimeAnalysisOfResonances/) The
experimental set-up can support undergraduate and graduate education of
students of physics, physics education and engineering by means of experimental
demonstrations and laboratory exercises. The very low cost, high efficiency and
transparent system provides a scalable experimental environment that can be
easily built in several instances.
