Patent ID: 7561058

Claim:
In an electrical device powered by external electric power, a method of warning of an unsafe condition in the electrical device after the external electrical power has been removed from the electrical device, the method comprising: within the electrical device, coupling the external electrical power to a capacitor and storing electrical energy in the capacitor so that electrical power can be provided within the electrical device after the external electrical power has been removed from the electrical device; using the stored electrical energy to provide a perceptible warning so that the warning continues until the stored electrical energy has been depleted below a predetermined level; sensing a property of the electrical device that results in the unsafe condition; and using the sensed property to adjust a magnitude of the current flowing from the capacitor to set a rate at which the stored electrical energy is depleted, wherein using the sensed property to adjust the magnitude of the current flowing from the capacitor comprises connecting the capacitor to at least one of a plurality of resistors having different resistances.