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Test equipment

The term test equipment covers everything from a simple gadget for checking continuity to a computer-controlled rig that automatically checks the operation of a newly manufactured DVD player. Here we look at the principles of circuit testing, describing the equipment that might be used by a typical service engineer.

The moving-coil meter

Nowadays, most meters have a digital readout, but the old-fashioned moving coil meter, with its needle moving over a graduated scale, still has many uses and is preferred by some people. Its operation relies on the fact that if a coil carrying a current is placed in a magnetic field, a force will act upon the coil. The coil (see opposite) is wound on a former of aluminium over a cylindrical iron ...

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