Abstract: An encoder delivers a pulse input signal in phase with equal angular steps of a rotary component, such as a toothed wheel driven by the crankshaft of an internal combustion engine. A missing tooth defines a reference position at which a synchronizing signal is also delivered. A counter is incremented by the pulse input signal and is reset by the synchronizing signal. A comparator compares the count in the counter with a number in a memory circuit to deliver a signal for triggering an event when the count in the counter coincides with the number in the memory circuit. The counter comprises a first counting circuit providing the least significant outputs of the counter and a second counting circuit providing the most significant outputs. The first counting circuit is reset by the input signal, and the second counting circuit by the synchronizing signal.

Abstract: The process and the device enable the electrical powering of a circuit having a conductor (1) with high thermal inertia by means of a transistor (3) with low thermal inertia. According to the invention, the device comprises a current limiter circuit (4,5,7,11), a voltage detector circuit (8) and a control microprocessor (6) which, according to a pre-established program, controls the flowing and stoppage of current in the power transistor (3) controlling the powering of the conductor (1) with high thermal inertia.Application to the control of lights in automobile vehicles.

Abstract: This system includes hysteresis comparison means (6, 9) whose output goes from a first state to a second state when the voltage of the ignition signal (S.sub.A) passes a predetermined high threshold and returns from the second state to the first state when the voltage of the ignition signal drops below a predetermined low threshold, a flip-flop circuit (8) triggered by the means of comparison (6, 9), and whose output delivers the said synchronous signal (S.sub.S), and a duration discriminator circuit (7) which only authorizes the switching over the flip-flop circuit (8) in response to the change in the output of the comparison means (6, 9) from the second state to the first state when the said output remains in the first state for a duration at least equal to a predetermined value. This invention may be used for measurement of the speed of an internal combustion engine.