Switchboard lamp cartridge plug

Claim 1

A lamp cartridge plug for switchboards comprising a light emitting diode having a pair of leads, an insulating cap for supporting said diode, said cap being sleeve-shaped with a light emitting part of said diode disposed at a front cap end for external viewing, said diode leads extending from the rear cap end, a cartridge housing of molded, non-metallic material, said housing having a front sleeve portion disposed about the cap with the light emitting part extending forwardly of the housing sleeve front end, said housing sleeve portion having laterally spaced fingers extending rearwardly of said cartridge, terminating in a dual lead support rear cartridge portion, at least one ballast resistor disposed in said housing at a region between said spaced fingers, a pair of stiff wire leads extending longitudinally of said cartridge, supported in said rear cartridge support portion and extending rearwardly straight from said cartridge, said stiff wire leads being electrically connected through at least one ballast resistor to said diode, said housing outer surface being cylindrical and dimensioned to be insertable as a plug in a signal panel aperture and said stiff leads cooperating with contact blades of a signal panel mounted jack, each diode unit being exposed to atmosphere in front of the panel and longitudinally spaced from a ballast, the ballast being located beyond the rear face of a signal panel, whereby an array of lamp cartridge plugs will have ballast resistors freely accessible to open air in the rear of said signal panel for heat dissipation and individual cartridges may be removed or replaced in case of failure or change in operating conditions.