Transmission photometer with holder for specimen cuvette - has LED illuminating cuvette, sensor photodiode and signal amplification, conversion and display system

摘要

The specimen cuvette (K) is illuminated by a LED (PL1,PL2). The light is fed to a sensor photodiode (PS) after attenuation and/or modification by the contents of the cuvette. The photodiode signal is amplified and converted for display in analogue and/or logarithmic and/or digital form. The LED is supplied with a frequency higher than a background light frequenc via a current defining resistor (R1,R2). The photosensor signal is filtered by a high pass filter (BP) with d.c. suppression whose pass band contains the supply frequency. The filtered signal is fed to a dual-path rectifier (GL) followed by a low pass filter (TP) whose output is displayed. ADVANTAGE - Simple transmitted light photometer of low wt., low current consumption. Easy to use yet sufficiently accurate.