Led light string with split bridge rectifier and thermistor fuse

Abstract

A string of lights has an electrical plug at one end and a receptacle at the other end and plural light-emitting diodes (LEDs) in series with a negative temperature coefficient (NTC) thermistor. The device also includes a bridge rectifier providing direct current to the LEDs and the thermistor but split between the plug and receptacle of the light string so that alternating current from the plug is delivered to the receptacle but direct current flow through the LEDs. Light string fuses protect the string but the NTC fuses protect the LEDs at a lower current rating. The LEDs can be arranged in a simple electrical series, or, in an alternative embodiment, an electrical series of groups of plural LEDs each of which is arranged electrically in parallel with other LEDs of the same group. The use of the lower-current-rating NTC thermistor allows the LEDs in one light string to fail without necessarily jeopardizing the current flow to subsequent light strings unless the current is high enough to blow the light string fuses in the plug.