Abstract: A control device for a laundry drier of the kind in which mechanical movement of the laundry load in a drum causes the article(s) constituting the load to form an electrically resistive connection between contact electrodes 5 and 6 in the drum. An a.c. sensing current is fed from a transformer T1 via the load and through a series capacitor C2 such that the voltage across the capacitor C3 is an inverse function of the state of dryness of the articles. This voltage is compared in a comparator TR1 with a reference voltage Vref which is chosen so that the comparator TR1 produces an output signal when the articles of the load have reached a predetermined dryness. Any electrostatic charges developed in the load are suppressed by a unidirectional low impedance shunt comprising a diode D8 and a resistor R12 in series.

Abstract: A control device for a laundry drier in which tumbling of the load articles causes them to form intermittent connections between contact electrodes. The control device is responsive to the state of dryness of the load includes means for causing an electrical current flow through a resistor, the electrodes and the load articles such that a potential difference is developed across the resistor. This potential difference is applied to a comparator for comparison with a reference potential value. A resettable timing circuit is reset to the beginning of a fixed time interval whenever the detected potential difference exceeds the reference value and the timing circuit operates an output switch only if no resetting action has occurred in that time interval.