Abstract: A debris alarm device for use with a particle analyzing apparatus of the Coulter.RTM. type generates discrete particle pulses in response to liquid suspended particles passing through a sensing aperture, the debris alarm comprising threshold circuitry for generating a threshold pulse for each particle pulse; circuitry for generating, for each threshold pulse, a normal pulse of predetermined duration; a first current source and a second current source for providing currents of opposite polarity to an integrator, when said current sources are triggered, respectively, by the threshold pulses and the normal pulses; and debris indicator circuitry, including an alarm, for determining when the output voltage of the integrator, which initially is set to zero, falls out of a predetermined voltage window.