Abstract: An A.C. powered smoke detector with supervision circuit for back-up battery. The circuit periodically and automatically, checks the power capacity of the back-up battery by momentarily disabling the D.C. power supply from applying D.C. voltage on a D.C. voltage bus while simultaneously applying a test load to the battery. If the test load voltage is too low, a low battery power capacity indication is provided. In one embodiment, the D.C. power supply is disabled by electrically disconnecting it from the battery. In another embodiment, a switch applies to effectively by pass the D.C. power supply and enable the application of the test load.

Abstract: A strain gauge assembly of the type having an elongate flexible member (12) with attached strain gauges (36, 38) has forces applied thereto at points (48, 50) spaced from its central neutral plane (52) by means including members mounted to a foot (10) and force receiving (14) members for non-sliding lateral movement relative thereto. In another embodiment strain gauges are attached to a flexible diaphragm (68) which is in communication with a fluid contained within a flexible sealed container (78) that is restrained against lateral movement by a hollow restraint member (62) therearound but which has a portion (80) protruding from a lower open end (66) thereof to receive a load to pressurize the fluid for flexing the diaphragm (68).

Abstract: A strain gauge assembly of the type having an elongate flexible member (12) with attached strain gauges (36, 38) has forces applied thereto at points (48, 50) spaced from its central neutral plane (52) by means including members mounted to a foot (10) and force receiving (14) members for non-sliding lateral movement relative thereto. In another embodiment strain gauges are attached to a flexible diaphragm (68) which is in communication with a fluid contained within a flexible sealed container (78) that is restrained against lateral movement by a hollow restraint member (62) therearound but which has a portion (80) protruding from a lower open end (66) thereof to receive a load to pressurize the fluid for flexing the diaphragm (68).

Abstract: A power supply for an electrostatic air cleaner incorporates a high frequency oscillator and a step-up transformer. The transformer includes a primary winding in series with a transistor, a secondary winding which cooperates with a voltage multiplying means to produce a desired output voltage for energizing the cell, and a feedback winding. The feedback winding is connected in circuit with the emitter-base circuit of the transistor and is responsive to voltage induced therein for effecting repetitive conduction and non-conduction of the transistor. The feedback winding is further connected in circuit with circuit means for adjusting and limiting the biasing of the transistor.