Circuit energization indicator with thermal timing means to maintain the indication for a predetermined time after de-energization

A thermal timer produces a timed duration output in response to a thermal input to a thermal storage device and a thermal energy leakage parameter from that storage device. The storage device preferably is a metal slug positioned in a silica aerogel insulative powder environment, and the thermal input is supplied by an electrically energized PTC heater. A thermostat output device monitors the temperature of the heater and the storage device to effect a distinguishable output, for example, by completing or opening an electrical circuit, in response to the temperature thereof. The thermal timer may be utilized in a range appliance or the like to effect a warning indication during cool down of that appliance.