Abstract: A time display is comprised of a low cost low accuracy RC oscillator. A series of pulses derived from this oscillator, for example, with a period of 1 second, is used for controlling a diode. An accurate time-display function of a car radio is also derived from this oscillator. This is possible as the main micro-controller periodically calibrates the low accuracy oscillator using a high accuracy crystal clock. Specifically, it measures the PC oscillator period in order to correct, in the micro-controller, the time issued from the RC oscillator.