Battery power supplies for medical ventilators; Carrying cases, holders, protective cases and stands featuring power supply connectors, adaptors, speakers and battery charging devices, specially adapted for use with handheld digital electronic devices, namely, cell phones, MP3 players and personal digital assistants; DC/AC power converters; Digital switching systems comprised of interconnected electromechanical and solid-state power management enclosures with standard and custom keypads for user remote control, the foregoing for use on marine helms and land-based vehicle dashboards; High-frequency switching power supplies; High-voltage power supplies; Inverters for power supply; Power adapters; Power adapters for computers; Power controllers; Power inverters; Power supplies for lights, sirens and public address systems; Power supplies for plasma cutting machines and public address systems; Power supplies; Power supply connectors and adaptors for use with portable electronic devices; Voltage regulators; Voltage regulators for electric power; Voltage regulators for vehicles; Voltage stabilizers; Voltage stabilizing power supply