Patent ID: 7561397

Claim:
A current limiting device comprising: a constant current source circuit constructed and arranged to be connected to a direct current input voltage source and to regulate electrical current, and a resonance source circuit receiving current from the current source circuit and being constructed and arranged to be electrically connected with an electroluminescent (EL) lamp so as to receive alternating current, wherein the constant current source circuit and the resonance source circuit are constructed and arranged such that when current flows from the current source circuit to the resonance source circuit and to the EL lamp, a maximum peak current received by a user contacting an output of the device or contacting the EL lamp is less than about 0.7 mA, wherein the constant current source circuit includes a transistor, an emitter of the transistor is connected to the input voltage source, a current sensor is connected to a collector of the transistor, a first amplifier is connected with the current sensor to amplify a pass current, a resistance divider, establishing a reference voltage, is connected to a positive input of a second amplifier, a negative input of the second amplifier being connected to an output of the first amplifier, a base of the transistor is connected to an output of the second amplifier to complete a constant current feedback loop defined by the current source circuit.