Abstract: A power supply having a dual-polarity, automatically switchable high voltage output. The power supply includes apparatus for regulating low voltage including a comparator having a programming voltage input and a feedback voltage input. The low voltage is converted by low voltage dc conversion apparatus to both negative and positive polarity high voltage dc signals proportional to the electronic signal applied to the programming input. Apparatus for switching the high voltage output by remote control is provided such that in a first switching mode the high voltage output is derived from the output of the positive polarity conversion apparatus, and in a second switching mode the high voltage output is derived from the output of the negative polarity conversion apparatus.

Abstract: A leak detector comprising a housing having an axis on first and second compartments spaced along the axis and hermetically separated by a partition, the first compartment being closed to comprise a pressure envelope which is in communication with an evacuated space to be monitored for leakage, an ionization cell in the first compartment providing an electrical current determined by gas in that compartment, hermetically sealed feed-through for enabling an electrical connection with the gauge, to the partition from the second compartment, an apparatus in the second compartment performing a control function in accordance with the current supplied by the cell.