A fan for generating an air flow by rotating an impeller with a motor is provided. A training data set of documents, each document having a pre-assigned records classification instance, is processed by a classification agent operating in training mode to establish a probabilistic relationship between each classification instance and the contents of a document. Secondary windings of the first and second pulse transformers are connected to control terminals of the transistors. The device can select a push mode where a pull message can accompany a push message.