Method and circuit for producing measuring pulses in a particle analyzer

摘要

A method of, and circuit for, producing measuring pulses in a particle analyzer for the analysis of particles suspended in a liquid, especially blood cells, comprising a conductivity or measuring cell, whose impedance between two terminals of the conductivity cell changes upon passage of a particle through such conductivity cell. A controllable current supply powers the conductivity cell with a current regulated to maintain a reference value corresponding to a control value. A receiver functioning as a high-pass filter and having high input impedance serves for the essentially currentless removal of a potential between the terminals of the conductivity cell and for forming a receiver signal corresponding to such components of such potential whose frequency is above a threshold or cut-off frequency corresponding to the high-pass filter. The control value is formed from the sum of a predetermined reference value and the received signal. There is formed a measuring signal proportional to the difference of the control value and the reference value and whose timewise changes correspond to the measuring pulses.