Abstract: An infant warming system includes a body temperature probe, a peripheral temperature probe, and at least two identical input jacks, each input jack configured to receive either one of the first connector or the second connector. The body temperature probe has a body temperature sensor removably fixable to an infant's torso to measure a body temperature of the infant, and a first connector configured to connect to an input jack to transmit the body temperature measurement. The peripheral temperature probe includes a peripheral temperature sensor removably fixable to the infant's extremity to measure a peripheral temperature of the infant, and a second connector configured to connect to an input jack to transmit the peripheral temperature measurement. The system further includes a probe detection module to automatically detect whether each input jack is connected to the peripheral temperature probe or the body temperature probe.

Abstract: The invention describes a method of predicting a stabilization temperature (T?) of a subject (8) with a heat-flow sensor (1) comprising a plurality of thermistors (S1, S2, S1A, S2A, S1B, S2B), which method comprises the steps of expressing the temperature development of the heat-flow sensor (1) as a stretched exponential equation characterized by a time constant (?) and a sensor characteristic scalar value (m); receiving temperature measurement values (T1, T2, T3, T4) collected by the thermistors (S1, S2, S1A, S2A, S1B, S2B); estimating the time constant (?) on the basis of the temperature measurement values (T1, T2, T3, T4); and deducing the future stabilization temperature (T?) on the basis of the estimated time constant (?). The invention further describes heat-flow sensor (1) and a temperature sensing arrangement (9).

Abstract: A composite-material molding apparatus for molding a composite material, wherein the molding apparatus is provided with: a main body; a composite-material layer in which a molding face for molding a composite material is formed, the composite-material layer coating the surface of the main body; a filamentous fiber-optic temperature sensor embedded in the composite-material layer; a heating unit provided inside the main body; and a control device for controlling the heating unit on the basis of the temperature measured by the fiber-optic temperature sensor; the fiber-optic temperature sensor being disposed in planar fashion in a plane parallel to the molding face.

Abstract: An animal wellness notification system includes an attachment body configured to securely engage with an ear of the animal; an elongated temperature probe secured to the attachment body and configured to extend within the ear of the animal; a housing secured to the attachment body; a computer disposed within the housing and operably associated with the temperature probe; and a notification device in data communication with the computer, the notification device being configured to provide notice if a temperature of the animal goes beyond a determined threshold.

Abstract: An animal wellness notification system includes an attachment body configured to securely engage with an ear of the animal; an elongated temperature probe secured to the attachment body and configured to extend within the ear of the animal; a housing secured to the attachment body; a power module electrically connect to and configured to provide power to (or recharge) at least one other element of the animal wellness notification system; a computer disposed within the housing and operably associated with the temperature probe; and a notification device in data communication with the computer, the notification device being configured to provide notice if a temperature of the animal goes beyond a determined threshold.

Abstract: An animal wellness notification system includes an attachment body configured to securely engage with an ear of the animal; an elongated temperature probe secured to the attachment body and configured to extend within the ear of the animal; a housing secured to the attachment body; a computer disposed within the housing and operably associated with the temperature probe; and a notification device in data communication with the computer, the notification device being configured to provide notice if a temperature of the animal goes beyond a determined threshold.

Abstract: A signal processing device (100) includes a prediction circuit (20) configured to generate Vb_T2 corresponding to an output signal to be obtained at T2 after T1, in accordance with Va_T1 obtained at the time T1, in a transition response period before Tr or Td elapses, where Tr denotes a time period during which an output signal Va(T) of a sensor (80) changes from a converged value Vc1 corresponding to a parameter P1 representing a certain property of an object to be measured to a converged value Vc2 corresponding to P2, and Td denotes a time period during which Va(T) changes from Vc2 to Vc1. The prediction circuit generates the predicted value so that TrE<Tr, TdE<Td, |1?Td/Tr|>|1 ?TdE/TrE| are satisfied, where TrE denotes a time period during which the predicted value becomes a value corresponding to Vc2, and TdE denotes a time period during which the predicted value becomes a value corresponding to Vc1.

Abstract: A fuel control device and method of a gas turbine combustor, for advanced humid air turbines, in which plural combustion units comprising plural fuel nozzles for supplying fuel and plural air nozzles for supplying air for combustion are provided. A part of the plural combustion units are more excellent in flame stabilizing performance than the other combustion units. A fuel ratio, at which fuel is fed to the part of the combustion units is set on the basis of internal temperature of the humidification tower and internal pressure of the humidification tower to control a flow ratio of the fuel fed to the plural combustion units.

Abstract: A conventional power supply device has a problem in miniaturization. A power supply device generates a prediction value of an error signal from first and second error signals, and controls an output voltage so that the prediction value lies between first and second threshold values. The first error signal is obtained by converting an error voltage based on the difference between the output voltage and a reference voltage at a first timing. The second error signal is obtained by converting an error voltage based on the difference between the output voltage and the reference voltage at a second timing.

Abstract: Providing a fast response to a process step while allowing a sensor response to remain relatively slow. A mechanical component generates a response to a step change in a physical property and an electrical component generates an analog electrical signal indicative of the response generated by the mechanical component over a period of time. The analog electrical signal is converted into digital values and the digital values are used to indicate the final value of the step change in the physical property before the period of time has elapsed.

Abstract: There is provided a high responsivity device for thermal sensing in a Terahertz (THz) radiation detector. A load impedance connected to an antenna heats up due to the incident THz radiation received by the antenna. The heat generated by the load impedance is sensed by a thermal sensor such as a transistor. To increase the responsivity of the sense device without increasing the thermal mass, the device is located underneath a straight portion of an antenna arm. The transistor runs substantially the entire length of the antenna arm alleviating the problem caused by placing large devices on the side of the antenna and the resulting large additional thermal mass that must be heated. This boosts the responsivity of the pixel while retaining an acceptable level of noise and demanding a dramatically smaller increase in the thermal time constant.

Abstract: A method and apparatus is presented for obtaining of accurate measurements of the temperature of a thermocouple and high fidelity measurements of the rate of change of the temperature of a thermocouple. A first sub-circuit is connected to the thermocouple with two conductors made of two different thermocouple alloys which are substantially the same as the alloys used in the construction of the thermocouple. A second sub-circuit is connected to the thermocouple with two conductors made of substantially identical material, such as copper. The first sub-circuit provides an accurate measurement of the temperature of the thermocouple. The second sub-circuit provides a high fidelity measurement of the rate of change of the temperature of the thermocouple.

Abstract: Described is a method and apparatus for compensating for a change in an output characteristic of a temperature sensor due to varying temperature. The temperature sensor includes a temperature sensing core, an analog-to-digital converter, a counter, and a temperature compensating circuit. The temperature sensing core generates a sense voltage corresponding to a sensed temperature. The analog-to-digital converter converts the sense voltage into a digital signal and generates a conversion signal. The temperature compensating circuit generates a counter clock signal that varies according to a temperature change. The counter counts the number of pulses of the counter clock signal according to the conversion signal.

Abstract: An apparatus including a temperature-sensing circuit. The temperature-sensing circuit can include an amplifier. The amplifier can include a positive input and a negative input. The negative input can be configured to be driven by a temperature-independent signal. A first transistor electrically can be connected to the positive input. The first transistor can be configured to be controlled by a temperature signal. A temperature threshold resistance and a hysteresis resistance can be electrically connected in series to the positive input. A second transistor can be electrically connected in parallel with the hysteresis resistance.

Abstract: An electronic thermometer is configured for selectable predictive modes based upon the same predictive algorithm. A mode selector is adapted for user selection between several modes of operation of the thermometer. Each mode of operation utilizes the same predictive algorithm for estimating the temperature of the subject before the thermometer reaches full equilibrium. Different modes offer users a selection for striking the appropriate balance between response time and precision, based upon user preferences and needs.

Abstract: A system is disclosed that essentially eliminates the delay in measurement of temperature by a sensor due to exponential response of the sensor. The system finds the rate of change of the sensor signal, multiplies it by the time constant of the sensor signal and adds the result to the instantaneous value of the sensor signal to predict the final value of the sensor signal or the actual value of the temperature. When the sensor is permanently attached to an object, the final temperature of the object is predicted in a similar manner using the combined time constant value of the sensor and the object. The system can be software, analog hardware or digital hardware. The system also allows more accurate temperature control without undershoot or overshoot by providing a control signal proportional to the difference between a desired value and the predicted final value of the sensor signal. The system similarly eliminates the time delay in measurement and control of flow in thermal flow meters.

Abstract: An electronic clinical thermometer having a low frequency of errors can be implemented. The electronic clinical thermometer for predicting an equilibrium temperature based on a temporal change in the actual measurement value of a temperature at a measurement target detected by a temperature detection element includes an abnormal change detection unit which detects an abnormal change of an actual measurement value from the temperature detection element, and a control unit which controls the start timing of a temporal change in actual measurement value used for derivation of a prediction value when the abnormal change detection unit detects an abnormality.

Abstract: A semiconductor device that may include temperature sensing circuits is disclosed. The temperature sensing circuits may be used to control various parameters, such as internal regulated supply voltages, internal refresh frequency, a word line low voltage, or the like. In this way, operating specifications of a semiconductor device at worst case temperatures may be met without compromising performance at normal operating temperatures. Each temperature sensing circuit may include a selectable temperature threshold value as well as a selectable temperature hysteresis value. In this way, temperature performance characteristics may be finely tuned. Furthermore, a method of testing the temperature sensing circuits is disclosed in which a current value may be monitored and temperature threshold values and temperature hysteresis values may be thereby determined.

Abstract: A method for digitally controlling the resistive output of a temperature probe is disclosed. The system is comprised of a temperature sensor, a processor and a means under the control of the processor for modifying the resistive output such as a digital potentiometer. In one embodiment, the processor reads the temperature sensor and adjusts the potentiometer based on a correlative or predictive technique so as to provide a modified output that matches that of a standard resistive temperature probe and is compatible for display on a multi-parameter monitor.

Abstract: An electronic thermometer includes a temperature sensing means for sensing a temperature of a part to be measured, and a prediction means for calculating an equilibrium temperature according to the temperature being sensed. The prediction means includes a parameter determination unit for calculating parameters of a prediction function having three parameters to obtain an equilibrium predicted temperature, and an equilibrium predicted temperature calculation means for calculating an equilibrium temperature during a period of the thermal equilibrium time, based on the parameters determined by the parameter determination unit. The parameter determination unit determines parameters held by the prediction function, based on three (or two) sensed temperatures and the measuring times thereof.

Abstract: An electronic thermometer includes a temperature sensing means for sensing a temperature of a part to be measured, and a prediction means for calculating an equilibrium temperature according to the temperature being sensed. The prediction means includes a parameter determination unit for calculating parameters of a prediction function having three parameters to obtain an equilibrium predicted temperature, and an equilibrium predicted temperature calculation means for calculating an equilibrium temperature during a period of the thermal equilibrium time, based on the parameters determined by the parameter determination unit. The parameter determination unit determines parameters held by the prediction function, based on three (or two) sensed temperatures and the measuring times thereof.

Abstract: An electronic clinical thermometer having a low frequency of errors can be implemented. The electronic clinical thermometer for predicting an equilibrium temperature based on a temporal change in the actual measurement value of a temperature at a measurement target detected by a temperature detection element includes an abnormal change detection unit which detects an abnormal change of an actual measurement value from the temperature detection element, and a control unit which controls the start timing of a temporal change in actual measurement value used for derivation of a prediction value when the abnormal change detection unit detects an abnormality.

Abstract: An electronic clinical thermometer capable of high-precision measurement within a shorter period of time. The electronic clinical thermometer for predicting an equilibrium temperature based on a temporal change in actual measurement value of a measurement target temperature detected by a temperature detection element includes a prediction value derivation unit which derives a plurality of prediction values from actual measurement values in accordance with a plurality of prediction equations, a selection unit which selects one of the plurality of prediction equations based on the selected prediction equation, and a display output which displays a prediction value result based on the selected prediction equation.

Abstract: A thermometer system and method that rapidly predict body temperature based on the temperature signals received from a temperature sensing probe when it comes into contact with the body. A nonlinear, multi-parameter curve fitting process is performed and depending on the errors in the curve fit, parameters are changed or a prediction of the temperature is made. Criteria exist for the differences between the curve fit and the temperature data. The processor switches to a Continuous Monitor State if the curve fit over a limited number of time frames is unacceptable. Determining the start time on which the measurement time frame for prediction is based is performed by tissue contact threshold coupled with a prediction time delay.

Abstract: A temperature detector and method of detecting a shifted temperature provides multiple detected temperature points using a single branch. The temperature detector generates multiple detected temperature points in response to temperature control signals sequentially generated in a single branch. Since a shifted temperature for the single branch is found and a trimming operation in response to the shifted temperature is carried out, the test time is reduced. Various refresh periods can be set in response to various trip point temperatures and thus power consumption of a DRAM can be decreased.

Abstract: A combustion temperature high speed detection device is provided with a phase lead processing portion, thereby canceling out a detection lag of a temperature detector, and detecting the combustion gas temperature of a combustor at a high speed. The combustion temperature high speed detection device is also provided with a first-order lag filtering portion with a time constant of 0.25 second, a phase lag processing portion with a time constant of 10 seconds, a temperature change filtering portion with a cutoff frequency of 2 to 3 Hz, and a disturbance filtering portion including first-order lag filtering portions with different time constants and a high value selecting portion. Thus, high speed detection of the combustion gas temperature more suitable for a gas turbine system can be performed.

Abstract: An object is to provide an inverter device capable of realizing exact protection of the winding of a motor. An inverter device for generating a pseudo alternating current by switching a direct current to drive a motor, comprises a controller that executes vector control on the basis of a secondary current applied to the motor. The controller calculates a current density from the secondary current to execute a predetermined protection operation on the basis of the calculated current density. The controller imposes a restriction on the operation frequency of the motor on the basis of the current density.

Abstract: A heat loss gauge for measuring gas pressure in an environment includes a resistive sensing element and a resistive compensating element. The resistive compensating element is in circuit with the sensing element and is exposed to a substantially matching environment. An electrical source is connected to the sensing element and the compensating element for applying current through the elements. The current through the sensing element is substantially greater than the current through the compensating element. Measuring circuitry is connected to the sensing element and the compensating element for determining gas pressure in the environment to which the sensing element and compensating element are exposed based on electrical response of the sensing element and the compensating element.

Abstract: An electronic clinical thermometer has a probe including a variable-temperature heater and one or more temperature sensors and may also include a heat flux sensor. Physical variables such as temperature, time rate of change in temperature and/or heat flow rate are directly measured at positions on the surface of a patient while being heated by the heater through a thermally insulating member. Such measured values are used to solve a heat transfer equation rewritten as lower-order equations. Measurements may be controlled to be taken at a desired timing such as at specified intervals. The probe for contacting the patient's body may be planar or in an elongated bar-shape.

Abstract: A heat loss gauge for measuring gas pressure in an environment includes a resistive sensing element and a resistive compensating element. The resistive compensating element is in circuit with the sensing element and is exposed to a substantially matching environment. An electrical source is connected to the sensing element and the compensating element for applying current through the elements. The current through the sensing element is substantially greater than the current through the compensating element. Measuring circuitry is connected to the sensing element and the compensating element for determining gas pressure in the environment to which the sensing element and compensating element are exposed based on electrical response of the sensing element and the compensating element.

Abstract: In accordance with the presence or absence of heat, a transistor shows a relatively rapid change, while a cooling water CLW shows a relatively gentle change. The temperatures of both members settle down to approximately equal temperatures when no heat is generated in the transistor. At this time, the temperature of one of the transistor or the cooling water and the amount of energization of the transistor are used to estimate the temperature of the other member. This method is applied to other temperature estimations, such as estimation of the temperature between a stator coil and a stator iron core of a motor etc.

Abstract: A method and device for rapidly predicting the temperature of an object through a sensor reading of the object's temperature by using a processor comprising finite impulse response (FIR) filters to determine the average value, the first derivative, and the second derivative of the sensed temperature based upon a predetermined number of temperature samples, apply a respective weighting factor to each of the average value, the first derivative, and the second derivative respectively, and calculate a temperature estimate by combining the weighted average value, the first derivative, and second derivative together with an offset factor.

Abstract: A temperature meter for measuring temperature of a measurement target object to which a temperature sensor cannot be fixed directly is formed by a temperature sensor configured to measure an observed temperature in a vicinity of the measurement target object; a timer configured to measure a temperature observation time; and a calculation processor configured to calculate the temperature of the measurement target object according to the observed temperature and the temperature observation time by carrying out a prescribed calculation processing.

Abstract: Methods and apparatus for reducing temperature overshoot in an engine, such as in a gas turbine aircraft engine, are described. In an exemplary embodiment, an unmeasured temperature to be regulated in an engine is determined by measuring a temperature in the engine wherein the measured temperature being related to the unmeasured temperature, determining a bias of the measured temperature wherein the bias being an amount estimated to be a difference between the measured temperature and a steady state measured temperature and adding the bias to the measured temperature to restore the relationship between measured and unmeasured temperature so that the unmeasured temperature may be properly regulated. The bias is determined using a heat transfer model.

Abstract: An electronic clinical thermometer has a probe including a variable-temperature heater and one or more temperature sensors and may also include a heat flux sensor. Physical variables such as temperature, time rate of change in temperature and/or heat flow rate are directly measured at positions on the surface of a patient while being heated by the heater through a thermally insulating member. Such measured values are used to solve a heat transfer equation rewritten as lower-order equations. Measurements may be controlled to be taken at a desired timing such as at specified intervals. The probe for contacting the patient's body may be planar or in an elongated bar-shape.

Abstract: A temperature management apparatus for foodstuffs stored in a storage cabinet, wherein a temperature sensor is placed in the storage cabinet to detect an inside temperature of the cabinet thereby to calculate an ambient temperature of the foodstuffs based on the detected inside temperature, and wherein an internal temperature of the foodstuffs is presumed on a basis of the calculated ambient temperature. The temperature management apparatus is provided with a foodstuff temperature indicator for indicating the presumed internal temperature of the foodstuffs and an alarm device for issuing an alarm sound when the presumed internal temperature of the foodstuffs becomes lower than a lower limit temperature or higher than an upper limit temperature.

Abstract: A thermometer having a symmetrical probe with a sensor for sensing temperatures and a processor, a method for calculating temperature of an object by a second-order differential equation comprises the steps of obtaining temperatures from object, performing a first temperature calculation to obtain an initial prediction of temperature of object, adding a compensation coefficient, generating a compensated temperature based on a combination of initial prediction of temperature of object and compensated coefficient, and calculating a stabilized prediction of temperature of object based on compensated temperature before sensor has reached temperature of object. This thermometer can effectively decreasing error during heat transfer process.

Abstract: A test wafer for use in temperature prediction is prepared. The test wafer includes: first semiconductor layer formed in a crystalline state; second semiconductor layer formed in an amorphous state on the first semiconductor layer; and passivation film formed over the second semiconductor layer. Next, the test wafer is loaded into a device fabrication system and then heated therein at a predetermined period of time. Thereafter, a recovery rate, at which part of the second semiconductor layer recovers from the amorphous state to the crystalline state at the interface with the first semiconductor layer, is calculated. Then, a temperature of the test wafer that has been heated is measured according to a relationship between the recovery rate and a temperature corresponding to the recovery rate.

Abstract: A temperature management apparatus for foodstuffs stored in a storage cabinet, wherein a temperature sensor is placed in the storage cabinet to detect an inside temperature of the cabinet thereby to calculate an ambient temperature of the foodstuffs based on the detected inside temperature, and wherein an internal temperature of the foodstuffs is presumed on a basis of the calculated ambient temperature. The temperature management apparatus is provided with a foodstuff temperature indicator for indicating the presumed internal temperature of the foodstuffs and an alarm device for issuing an alarm sound when the presumed internal temperature of the foodstuffs becomes lower than a lower limit temperature or higher than an upper limit temperature.

Abstract: In the processing of an item, particularly a food item, where the final equalized temperature is important to the processing a method and apparatus for predicting the equalized temperature is disclosed. A series of infrared sensors is used to measure the rate of change of the surface temperature of an item after the item is exposed to a known thermal shock such as heating or cooling. The predicted equalized temperature can be calculated from the series of surface temperatures using least squares, non-linear regression techniques. One means for applying a thermal shock to an item would be the use of cryogens such as liquid nitrogen, carbon dixoide snow or synthetic liquid air (SLA).

Abstract: In accordance with the presence or absence of heat, a transistor shows a relatively rapid change, while a cooling water CLW shows a relatively gentle change. The temperatures of both members settle down to approximately equal temperatures when no heat is generated in the transistor. At this time, the temperature of one of the transistor or the cooling water and the amount of energization of the transistor are used to estimate the temperature of the other member. This method is applied to other temperature estimations, such as estimation of the temperature between a stator coil and a stator iron core of a motor etc.

Abstract: A method and device for rapidly predicting the temperature of an object through a sensor reading of the object's temperature by using a processor comprising finite impulse response (FIR) filters to determine the average value, the first derivative, and the second derivative of the sensed temperature based upon a predetermined number of temperature samples, apply a respective weighting factor to each of the average value, the first derivative, and the second derivative respectively, and calculate a temperature estimate by combining the weighted average value, the first derivative, and second derivative together with an offset factor.

Abstract: An intelligent input/output (I/O) temperature sensor includes a temperature sensing element which generates a plurality of digital data indicative of the temperature at the temperature sensing element, a processor directly coupled to the temperature sensing element which generates a plurality of compensated digital data from respective the digital data and a digital delta value, and a memory directly coupled to the processor which stores the digital delta value and the compensated digital data. According to one aspect of the invention, the memory is an electrically erasable programmable read only memory (EEPROM). According to another aspect of the invention, the memory, the temperature sensing element and the processor are all disposed within a unified structure, i.e., on a single chip. A method for calibrating an intelligent input/output (I/O) temperature sensor is also described.

Abstract: A digital thermometer, having a sensing tip that is integral with a heater, a display, and a microcontroller which samples for rise time and proportionally operates the heater to increase the temperature of the sensing tip in an alternating control sequence that includes a post-heating delay and, thus, the sensing tip quickly arrives at a stable temperature when no further heating is required.

Abstract: A digital thermometer, having a sensing tip that is integral with a heater, a display, and a microcontroller which samples for rise time and proportionally operates the heater to increase the temperature of the sensing tip in an alternating control sequence that includes a post-heating delay and, thus, the sensing tip quickly arrives at a stable temperature when no further heating is required.

Abstract: A quick registering thermometer utilizing a sensor that has electrical resistance varying with temperature located at the tip of a probe, the sensor having relatively small thermal mass and short thermal time constant. Within seconds of contact with the patient, the circuitry communicating with the sensor determines the rate of change in resistance of the sensor and, in turn, the temperature that the sensor would reach if allowed the length of time it would need to reach equilibrium with the contact surface of the patient. Based on the equilibrium temperature determined for the surface of the patient, the circuitry calculates and registers the core body temperature.

Abstract: A quick registering thermometer utilizing a sensor that has electrical resistance varying with temperature located at the tip of a probe, the sensor having relatively small thermal mass and short thermal time constant. Within seconds of contact with the patient, the circuitry communicating with the sensor determines the rate of change in resistance of the sensor and, in turn, the temperature that the sensor would reach if allowed the length of time it would need to reach equilibrium with the contact surface of the patient. Based on the equilibrium temperature determined for the surface of the patient, the circuitry calculates and registers the core body temperature. Included in the circuitry is an error adjustment mechanism for changing the calculated temperature as a function of the number of displays of the thermometer in a given period of time.

Abstract: A thermostat for heating or cooling, operative to maintain an indoor air temperature to a limited setpoint range, is provided with a comparison circuit to prevent tampering intended to exceed a setpoint limit. A first temperature sensor responds to ambient air temperature and can include a first thermistor. A second thermistor is partly thermally isolated from the air, and senses a reference temperature that lags temperature changes in the ambient air. The two thermistors form a voltage divider coupled to one input of a differential amplifier comparator, the other input of which is coupled to a fixed voltage reference. When the ambient and reference temperatures exceed a predetermined temperature difference, the differential amplifier operates a relay that breaks a circuit including the contacts. This occurs when locally cooling the ambient air to generate a spurious call for heat (or vice versa).

Abstract: A device and a method for compensating for temperature fluctuations for maintaining the warmth of a cooker having an inverter circuit, which has a system controller which obtains a final compensation data by processing a temperature compensation data outputted from a compensation temperature selection section and a present temperature detected by a temperature detecting section. The system controller outputs a driving signal to drive a bottom heater, a top heater, and a side heater of the cooker according to a calculated final compensation data.

Abstract: A heat detector uses a single comparator operating in conjunction with a dynamically changing thermal reference that ensures quick response to rapid rates of thermal change and a fixed threshold that indicates an ambient temperature exceeds a threshold temperature. The inputs of the comparator receive different ones of the output signals of two thermal sensors. One thermal sensor responds nearly instantaneously to changes in ambient thermal conditions. The other thermal sensor is mounted on a printed circuit board operating as a heat sink and responds more slowly to changes in ambient thermal conditions. The difference between the thermal sensor output signals is zero at a lower ambient temperature when the rate of thermal change exceeds a preset amount and at a higher ambient temperature when the rate of thermal change is relatively slow.