Abstract: A circuit arrangement for controlling the duration of a current generated in the primary winding of an ignition transformer comprises a ramp generator responsive to the ignition timing or an internal combustion engine for generating a ramp voltage having a constant peak value and a variable rate of increase in voltage as a function of the speed of the engine. A pulse generating means is provided for successively generating a pulse of which the pulse height is substantially equal to the peak value of the ramp voltage and of which the pulse duration is variable inversely as a function of the speed of the engine. To the pulse generating means is coupled an integrator for integrating the pulses supplied thereto to generate an integrated output. The output of the integrator is supplied to a comparator for making a comparison with the instantaneous value of the ramp voltage to generate an ignition current pulse having a duration corresponding to the difference between the compared input variables.