For the course NB2211 – Electronic Instrumentation for Nanobiology - at Delft University of Technology a special Colorimeter board was developed. It is used for final in-class practical assignment, for which the students apply all gained knowledge on electronics, instrumentation and programming. The core part is a light-shielded box containing a multicolor LED, a cuvette holder, a multi-color photodiode, and a heater. Multiple options for the LED control are given (with a resistor, with a transistor or with a transistor + opamp regulation) . The frequency of the signal out depends on the measured intensity, and can be either used with 50% duty cycle, or adjustable pulse width.