Abstract: A I.sup.2 L circuit device including logical operation circuits comprising I.sup.2 L elements, wherein when main power supply is interrupted, an injector current is injected from an auxiliary current source circuit into part of the I.sup.2 L circuit device to thereby hold a logical value, so that when the main power supply is restored, the logical state having been prevailing prior to the interruption of the main power supply is restored. When applied to a drive circuit for a switch including a self-restore type contact, for example, this I.sup.2 L circuit device is operative such that the switch is set to a predetermined logical value; the logical value is stored in a storage circuit of the I.sup.

Abstract: An apparatus for detecting leakage of fluid comprises a bridge circuit composed of a heat generating resistance element connected in one arm and installed at a location where leakage of fluid may possibly occur and other resistor elements inserted in other arms, respectively, an input power supply source connected to the input of the bridge circuit and a differential amplifier connected to the output of the bridge circuit for amplifying an unbalance voltage produced by the bridge circuit, wherein the resistor elements inserted in the other arms of the bridge circuit are so dimensioned that the heat generating resistance element is maintained in a heat generating state.

Abstract: A fluid leakage detecting element comprises a heat generating resistive member and a temperature compensating resistive member disposed on a substrate. Each of the resistive members is prepared in the form of a paste of a metal which has a high temperature coefficient and a high thermal conductivity and whose melting point is higher than the baking temperature of the substrate. These resistive members are printed in thick film form on the substrate which is sufficiently electrical insulating and has a high thermal conductivity.

Abstract: In a multiple pushbutton switch assembly, a flexible restoring tape has both ends affixed to the casing at both ends with a predetermined slack in such a manner that it is tensioned by depressing any one of the sliders which, when depressed, are locked alternately at a switch-on position and a switch-off position by elastic springs. The amount of the predetermined slack of the restoring tape corresponds to the amount of depression of each slider, so that when one slider is depressed, another one which has been depressed is restored or returned to its initial position, and only one slider is allowed to be depressed at any one time.