Abstract: A power supply or inverter circuit is provided for regulating power to electroluminescent lamps over a range of lamp sizes. The power supply may have an AC and/or DC input and includes at least one switch having a power input to be coupled to an electrical power source, a control input, and an output to be coupled to an electroluminescent lamp for being switched on and off to generate a drive signal to the lamp having a predetermined constant frequency and current level that is selectable over a range of frequency and current levels. A constant current mode controller has a control output coupled to the control input of the switch for turning the switch on and off so as to maintain a constant current level and frequency of the drive signal to the electroluminescent lamp substantially over its operating life. The voltage applied to the lamp is allowed to increase to a predetermined voltage limiting value in order to provide compensation due to aging of the lamp.