Abstract: The present disclosure relates to mercury containing reed switches and to methods of preparing switch blades for use in such switches. Heretofore such reed switches have been doped with mercury after the reed switch blades have been mounted in the envelope, the mercury migrating to the contact area of the switch blades, made of a mercury-wettable material, after sealing. The present invention avoids the expense and complexity of this procedure by improving the control of mercury dosing to enable improved performance of such reed switches in low power applications, for example in automatic test equipment, process control equipment and data processing terminals.

Abstract: A reed switch having contact electrodes extending within a sealed envelope to overlap and form a magnetically actuable contact gap of the switch.Each contact electrode has flattened bladed portions which taper from their overlapping forward extremities to form blades of varying thickness, the thickest part of the blades being at the overlap between them.

Abstract: A temperature sensitive-trip device for use on an electrical surge arrestor and comprising a resilient contact member mounted on the arrestor and having a fusible material solidified in contiguous relationship therewith to hold contact member biassed so that on melting of fusible material, contact member is urged to a position in which it shorts the electrodes of the arrestor.

Abstract: This invention relates to a duplex surge arrestor comprising two gas-filled surge arrestors showing commoned electrodes through which commoned electrodes extends a passage for conveying ionised gas from one arrestor to the other, and in which duplex surge arrestor the electrodes are of such shape, disposition and material that when an excessive dissipation of energy occurs on any two electrodes therein, the discharging electrodes melt and fuse together.