Abstract: Force detector (5) fitted with a blade carrying a strain gauge (12) and with a fixed support (10) and a mobile support (11) in which are respectively accommodated a first and second end of the said blade, the relative displacements of the two supports enabling the forces applied to the mobile support to be detected. In order to accommodate at least one of the said ends in its own support, the said support comprises a U-shaped member (13), between the two branches of which is inserted the said end bearing on slightly elastic contacts. A tactile screen is formed with the help of a plurality of such force detectors accommodated in a mobile plate (22) and a fixed frame (21). By coupling the two latter elements by means of suspensions (24.sub.1, 24.sub.2) and elastic fasteners (25.sub.1, 25.sub.2), the pressure forces acting on the mobile plate are, in a vertical position, decoupled from the intrinsic weight of the latter.

Abstract: A control circuit comprising a thyristor and a feedback circuit formed by an inductance and a generator for producing electrical energy in response to a luminous event. The feedback circuit controls the conducting or cut-off state of the thyristor by the fact that a trigger-gate of the thyristor is connected to a terminal of the generator having a polarity cutting off the thyristor when the generator is illuminated. The thyristor is switched on in response to an energy stored in the inductance, which energy is caused by a sudden discontinuity of the luminous event.

Abstract: An electric flat-iron safety device includes a magnet pivotally supported in a flat-iron and arranged to actuate a first magnetically operated switch only when the flat-iron is in a horizontal ironing position and to actuate a second magnetically operated switch only when the flat-iron as tilted to a vertical rest position. Should the flat-iron remain motionless in the horizontal ironing position for a first predetermined time interval shorter than the time necessary for the flat-iron to reach its normal operating temperature, closure of the first switch by the magnet causes a resettable dual interval timing circuit to interrupt the power supply to the flat-iron. If the flat-iron remains motionless in the vertical tilted rest position for a second predetermined time for a interval longer than the time necessary for the flat-iron to reach its normal operating temperature, closure of the second switch by the magnet causes the dual interval timing circuit to interrupt the power supply.

Abstract: A door-open alarm device comprises alarm means connected to an electric circuit which comprises, arranged on the stationary part (11), a voltage source, a switch (13) having two positions in which the circuit is interrupted and closed respectively, electrical time delay means responsive to a current flow in the circuit to produce a voltage variation across said alarm means after a time delay, thereby triggering said alarm means. Arranged on the door (12) is a mechanical actuating element (14) for said switch, which opens said switch when the door is wide open or closed, and which closes said switch when the door is ajar.