  Photogates are probably the most commonly used electronic instruments to aid
experiments in the field of mechanics. Although they are offered by many
manufacturers, they can be too expensive to be widely used in all classrooms,
in multiple experiments or even at a home experimentation. Today all computers
have a sound card - an interface for analogue signals. It is possible to make
very simple yet highly accurate photogates for cents, while much more
sophisticated solutions are also available at a still very low cost. In our
review we show several experimentally tested ways of implementing sound card
photogates in detail, and we also provide a full-featured, free, open-source
photogate software as a much more efficient experimentation tool than the
usually used sound recording programs. Further information is provided in a
dedicated page, www.noise.physx.u-szeged.hu/edudev.
