This project provides instructions for building an impedance converter for the Raspberry Pi (a single-board computer), as used in physics labs for students at the faculty of physics at the Karlsruhe Institute of Technology.
Fig. 1: Illustration of the impedance converter with measuring case used in the “photoelectric effect”-lab experiment.
The framework for this is based on the PhyPiDAQ project by Prof. Dr. Günter Quast, which aims to provide access to state-of-the-art measurement technology and data acquisition tools to students.
In the physics lab at KIT, the charging curve of a capacitor is measured and digitized, whereby the capacitor is charged by the current of a photocell. The voltage difference across the capacitor be passed on to the ADC, without discharging the capacitor, via the high-impedance input and low-impedance output of the operational amplifier.