Abstract: A circuit for use with double riser elevator call systems having two sets of "up" and "down" elevator hall buttons per floor associated with respective signal lights. It comprises first and second substantially identical subcircuits each comprising a first resistive element in series with a capacitive element, a solid state variable impedance means in series with a unidirectional current conducting device, and connections from said first resistive means and said capacitive means to said variable impedance means. There is also a second resistive means in circuit between the junction of said first resistance means and said capacitance and the junction of said variable impedance means and said unidirectional current conducting device. A third resistance means has a first terminal connected to said latter junction and a second terminal connected to a corresponding second terminal of a corresponding third resistance means of said second subcircuit.