In scientific research, pulse amplitude or temporal distribution is often the analog of the phenomenon under investigation. Particularly is this true in nuclear studies, where pulse amplitude can be made proportional to energy and classification on an amplitude basis yields the energy spectrum. The present paper gives an outline of pulse amplitude analyzing equipment and indicates that for pulse widths of one microsecond and larger, as distinct from those in the millimicrosecond region, the thermionic diode leaves little to be desired as a voltage discriminating element.