Advertising sign system

Abstract

A low-voltage system is disclosed for supplying operating power to high-voltage neon light tubes located within housings in the forms of letters and other shapes commonly used for illuminated advertising on the outside of buildings. Within the building, a first step-down transformer is connected to the conventional household power supply of 110 volt 60 Hz current. The step-down transformer produces a low-voltage signal in the range of 16 to 24 volts at the 60 Hz operating frequency. The low-voltage wires are passed through the exterior wall of the building on which the advertising sign housing is mounted and require no special precautions or high-voltage insulation due to the extremely low voltage involved. Within each high-voltage lamp housing, a solid state low-voltage to high-voltage conversion circuit is mounted. The input to this circuit comprises the 16 to 24 volt 60 Hz low-voltage current. This signal is supplied to a full-wave rectifier, which supplies operating power to a high-frequency oscillator (10,000 Hz to 30,000 Hz), the output of which, in turn, is used to drive a power switching transistor connected to the primary winding of a step-up transformer. This high-frequency signal, as obtained from the secondary winding of the step-up transformer, is used to supply a high-voltage operating alternating current to the neon tube mounted within the sign housing.