Abstract: A device and process for examining the size of particles suspended in a liquid, in particular for determining the MCV of red blood cells, having a measurement aperture traversed by the suspension and two electrodes arranged in the region of the measurement aperture and connected to evaluation circuitry, each of which electrodes producing one pulse per particle passing therethrough, the amplitude of which pulse is a measure of the volume of the particle. A differential discriminator for the pulse amplitudes and a further discriminator are connected in front of the evaluation circuitry wherein the further discriminator permits the passage of only pulses whose duration is less than the duration of a pulse coming from a single particle which has a maximum amplitude determined by the differential discriminator.

Abstract: A circuit arrangement for determining the characteristics of liquids and/or gases, in particular for determining the diverse parameters of blood. The equipment determines the ratio of the signals of the sensing element resp. of the signal converter at a double-light photometer and a reference, simultaneously performing constant or periodical testing, accordingly, the control of the whole measuring system can be ensured. Signal processing takes place by the expansion of series or cutoff point interpolating logarithm forming, by averaging; the system includes structural elements for performing adjustable error detection. The largest advantage of the circuit arrangement according to the invention lies in that the instabilities of the photometers of traditional construction may be eliminated, a higher measuring accuracy becomes possible, and by ensuring the testing possibilities, by performing a continuous self-control reliable measuring data are delivered.