US Patent 7293914 Temperature detecting heater with indicating structure for aquarium

A temperature detecting heater with an indicating structure for an aquarium, the temperature detecting heater mainly has an indicating structure including a control circuit and a two-color LED indicating lamp in its circuitry. After the temperature detecting heater is turned on, temperature detectors of the control circuit detects a voltage to compare it with a reference voltage at a set point; when the temperature at the detected point is lower than that of the set point, a heating element of the temperature detecting heater is controlled to work normally and makes the LED indicating lamp show a first color, for instance, red; but when the temperature at the detected point is higher than that of the set point, the heating element of the temperature detecting heater is controlled to stop working and makes the LED indicating lamp show a second color, for instance, green. By emitting light showing two different colors from the two-color LED indicating lamp of the indicating structure, a user can clearly know whether the heating function of the temperature detecting heater is normal.