Double-beam photometer for evaluating the intensity of the change in colour of reagent strips

摘要

The photometer consists of a measuring cell (1) which is connected to an electronic changeover switch (10) and to a phase detector (9). A light-emitting diode (luminescent diode) (2) of the measuring cell (1) is connected to a working voltage/current transformer (11). A reference light-emitting diode (5) of the measuring cell (1) is connected to a reference voltage/current transformer (12) which is connected via a measuring potentiometer (13) to the working voltage/ current transformer (11). The measuring cell (1) is provided with a photo resistor (9) which is connected via an amplifier (7) and a block (8) for signal reconstruction to the phase detector (9), to which the output of the electronic changeover switch (10) is further connected, and whose output is fed to a balance indicator (14). <IMAGE>