Abstract: In order to protect a polarity-sensitive load from a reversed battery assembly, the drain and source electrodes of a MOSFET (or bipolar transistor) device are connected in series with the load and battery and its gate electrode is connected to or otherwise coupled to a node between a battery terminal and the load. If the battery is inserted with correct polarity, the transistor is turned on and inserts its small on-resistance into the circuit. If the battery is inserted with incorrect polarity, the transistor does not turn on, and the polarity-sensitive load is protected.

Abstract: A circuit for eliminating false triggering of a power device in an optically coupled drive circuit caused by dv/dt sensitivity of an optocoupler of the drive circuit comprising a latch circuit having an input coupled to an output of the optocoupler and having an inhibit input; and an inhibit signal generating circuit coupled to an output of the latch circuit for providing an inhibit signal of a preset period of time to the inhibit input of the latch circuit when the output of the latch circuit changes state, thereby inhibiting the passage of any high dv/dt spurious or noise signals to the output of the latch circuit during the preset period of time.

Abstract: A circuit and method for detecting and protecting against an overcurrent condition in a power transistor switching device, and particularly an IGBT. The power transistor switching device has main terminals and a control terminal, the main terminal having a normal saturation voltage therebetween during normal conduction of the power transistor device. The circuit includes a driver providing control signals to the control terminal of the power transistor device for switching the power transistor device on and off, a sensing circuit coupled to the power transistor device for sensing the saturation voltage of the power transistor device, and a switching circuit coupled to the control terminal of the power transistor device and responsive to the sensing circuit for removing the control signals from the control terminal in the event the saturation voltage reaches an abnormal level indicating an overcurrent condition in the power transistor device.

Abstract: A stable, thixotropic aqueous bitumen dispersion containing no emulsifier is prepared. Alkaline earth metal hydroxide and an aluminum salt are brought into contact to form an aqueous aluminum hydroxide gel. Molten bitumen is dispersed in the gel. The dispersion has a good shelf life and is stable with respect to electrolytes and chemically active construction materials.