Abstract: The invention relates to a fire detector having a measuring chamber defined by two electrodes, so that a non-ionizing electric field is produced between the electrodes by a DC voltage source. The measuring electrode is connected to the input of a current measuring device without direct connection with the DC voltage source. As soon as charged particles of smoke penetrate into the measuring chamber between the electrodes, the electric field causes the positive and negative particles to drift. The charge drift induces a current into the measuring electrode which is measured.