A timer advantageously in the form of a wristwatch and is combined with the time indicating function of the watch. The timer comprises a setting device enabling an accumulator to be loaded through the medium of a position transducer. The movement of the setting device being a stepwise one, each of its shifts enables a pulse to be generating which corresponds to a number of reference periods supplied by a time base. The accumulator is counted down by the time base and, when the accumulator is empty, a warning signal generating device is triggered.