Abstract: Sound signaling and optical signaling at a crosswalk are both activated by a single push button. An activation of optical signaling such as green and red figurines is immediate, whereas the transmission of a sound message authorizing or forbidding a crossing is activated only when the pedestrian pushes the button for a predetermined time. The generation device for sound signals is controlled by a microprocessor including logic and analog inputs and outputs, the messages being stored in digital form and transmitted according to the ADPCM method.

Abstract: A voltage regulation loop for the rejection of line frequency ripple of 0-180 Hz in an inverter power supply is disclosed. The loop includes an error amplifier (E), a pulse-width modulator (P), an inverter (I), a second summing node (N.sub.2), an output filter (F), and a feedback loop back to a first summing node N.sub.1 at the error amplifier. The novel pulse-width modulator is non-linearly operated to provide an improved rejection of the power supply's line frequency ripple and an improved stability.