Abstract: A control circuit for progressively and gradually varying the illumination intensity of incandescent lamps. The circuit comprises a source of alternating current connected in series with an electric lamp load which is also in series with a silicon controlled rectifier. This silicon control rectifier is rendered conductive when its gate is actuated by a gate signal generated by a programmable unijunction transistor (PUT). The conduction of the PUT depends on the voltage applied on its gate by a gate biasing circuit connected thereto and which comprises a charging capacitor. On the other hand, a charging circuit is connected across the silicon control rectifier whereas a second charging circuit is connected between the anode of the PUT and the first-mentioned charging circuit.