Abstract: A system, method and apparatus for protecting circuit components from unauthorized access. The circuit components to be protected are disposed on a first layer of a substrate with a plurality of layers. A cover member composed of a plurality of layers is abutted to the substrate, defining an enclosure space for enclosing the circuit components to be protected. A three-dimensional resistive network sensor surrounds the protected circuit components. The sensor comprises at least one conduction path in at least one of the layers below the first layer of the substrate and at least one conduction path in at least one of the layers of the cover member and also comprises a plurality of vias transverse to and electrically connecting the conduction paths. A short or open in the sensor will be detected by a tamper detection circuit that is disposed on the first layer of a substrate.

Abstract: A system, method and apparatus for protecting circuit components from unauthorized access. The circuit components to be protected are disposed on a first layer of a substrate with a plurality of layers. A cover member composed of a plurality of layers is abutted to the substrate, defining an enclosure space for enclosing the circuit components to be protected. A three-dimensional resistive network sensor surrounds the protected circuit components. The sensor comprises at least one conduction path in at least one of the layers below the first layer of the substrate and at least one conduction path in at least one of the layers of the cover member and also comprises a plurality of vias transverse to and electrically connecting the conduction paths. A short or open in the sensor will be detected by a tamper detection circuit that is disposed on the first layer of a substrate.

Abstract: An electronic ballast circuit for operating high intensity gas discharge tubes such as high pressure sodium, high pressure mercury and metal halide tubes, as well as ordinary fluorescent tubes. In the preferred embodiment, an inductance and a capacitance are connected in series with the load across the dc supply, with a solid state switch between the junction of the inductance and capacitance and the other side of the load, and a control circuit for the switch to operate the switch at a high frequency such as 20,000 hertz. Alternative embodiments omitting the capacitance and utilizing a transformer for the inductance are especially suited for less expensive units and for emergency lighting use. Power supply circuits with switching operated in conjunction with the previously mentioned switch provide for regulation of lamp output during start-up and for compensating changes in supply voltage coordinated with lamp aging.