In this paper, we discuss the theory of the operation and some practical considerations for the construction of an air ionization chamber, which can be used as a very simple detector of alpha particles. These detectors have several benefits compared to spinthariscopes and spark detectors. Classical experiments with ionization chamber detectors are presented. Ionization chambers equipped with a recording device, such as Arduino, are sensitive enough to evaluate the activity of lantern mantle alpha particle sources and uranium glass beads. Weak emitters are placed directly inside the chamber, which is then sealed with a shielding cap.