Thermometer Circuits
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Circuit shown in Figure: MAX6698 maximum temperature with three transistors (VT1 ~ VT3) and three thermistors (RT1 ~ RT3). The internal reference voltage source via a resistor ..
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A thermostat doesn't try to maintain a constant temperature. In order to do so - it would have to keep switching on and off every few seconds. Instead - it keeps the temperature within a specific range. When the preset temperature has been reached - it....
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the entire circuit is comprised of integrated circuits. This makes for some easy organization when it goes to the circuit board for soldering. In addition, I used only 3 of the pins on the 3rd nixie tube for the hundreds position in the display. Since I was....
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This circuit measures temperature in Celsius scale and displays it on an alphanumeric LCD screen. When temperature rise to 40 C an alarm is activated and at the same time a relay is also activated which drives a fan to keep the temperature at a level.....
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This circuit controls a load (in this case a dc brushless fan) based on a temperature compared with a setpoint. THe transduced is a diode in the forward polarization regime. In fact when forward biased, the forward voltage drop accross a diode has a....
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The LTC1392 is
designed to be used for PC board temperature and supply
voltage/current monitoring or as a remote temperature
and voltage sensor for monitoring almost any kind of
system. It is available in SO-8 and DIP packages allowing
it to fit onto....
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This circuit is intended for precision centigrade temperature measurement, with a transmitter section converting to frequency the sensor`s output voltage, which is proportional to the measured temperature. The output frequency bursts are conveyed into the....
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An economical and commercially available quartz temperature sensor, Y1 and IC1, an LTC-485 RS485 transceiver in transmitter mode, form a Pierce crystal oscillator. The sensor, an Epson HTS-206, presents a nominal frequency of 40 kHz at 25°C and a temperature....
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This is a very simple to implement Temperature Sensor. It uses LM35DT as a semiconductor temperature sensor which operates with a +5 volt DC.
It produces an analog output voltage, proportional to the change in surrounding temperature in Celsius scale....
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Using a thermistor in the position shown makes a heat activated sensor. A change in temperature will alter the output of the opamp and energize the relay and light the LED. Swapping the position of the< thermistor and 47k resistor makes a cold or frost....
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This circuit was built to stabilize a radio frequency VFO (Variable Frequency Oscillator) for ham radio applications. The circuit has also been used to lower the drift of a Ramsey FM10a micropower FM transmitter...
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The most common appl icat ion for the NTC thermistor
is temperature measurement. Accurate temperature
measurement can easily be accomplished by interfacing a
Wheatstone Bridge, 6K/30K ohm thermistor network and a
digital voltmeter integrated circuit....
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The following page outlines detail information on how to step by step design a Simple Heat Sensor Circuit. This circuit design utilized LM741 as the operational amplifier...
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The circuit consists of two parts: The LM335 and its adjustment. The output of the LM335 is 10 millivolts per degree C, with 25 degrees C corresponding to 2.982 VDC. A reference circuit provides a zero reference voltage. It is adjusted to (2.982 volts - (25....
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Room temperature plays a vital role in determining human thermal comfort. This digital thermometer is designed to measure room temperature and display it on a LCD screen in both Celsius and Fahrenheit scales. A PIC16F688 microchip is used as the main....
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This is a four-channel temperature measurmet adapter that works without external power supply. It will suitable for measureing temperature and logging its data with a PC. The circuit diagram is very simple and no adjustment is required, everybody will able....
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The Car Temperature Gauge is basically the same circuit as March's project with some minor changes to the input circuit. This circuit will display the water temperature to 1 degree resolution...
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The circuit drives the LCD pins with 50% square waves. Each segment on this LCD is connected to the COM backplane and a separate pin. When a pin is driven in phase with the COM pin, the corresponding LCD segment gets zero voltage, and is off. When a pin is....
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This is the fully featured, jammed packed temperature readout unit. I can measure temperature from up at 8 DS1820 digital temperature sensors all on the same 1-wire bus. That's right only 3 wires are needed to go to all the temperature sensors, GND, VCC and....
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The circuit is small regulatorof temperature, us warns for the increase of temperature. The control of temperature becomes from the thermistor TH1, that is negative factor. His resistance is altered between in the 10K in temperature 25° C and roughly in the....
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This circuit, is basically a resistance ? sensing window switch, except that the ?resistor? takes the form of an NTC thermistor and the circuit thus responds to temperature. TH1 must have a resistance in the range 500ohm - 9Kohm. RV1 is used to set half ?....
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This circuit controls a load (in this case a dc brushless fan) based on a temperature compared with a setpoint. THe transduced is a diode in the forward polarization regime. In fact when forward biased, the forward voltage drop accross a diode has a....
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This circuit controls very accurately a fan of any size. Just adjust the associated resistors for a different type like the R6 resistor of 100 ohm, 2 watt type and you're all set. The above circuit diagram is for a small 12 volt fan, the size and type....
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The Thermistor, or NTC (Negative Temperature Coefficient) of 10K, is a standard type. Most types will work. The one in the diagram is a 10K model made by Fenwal (#197-103LAG-A01). The resistance lowers as the surrounding temperature increases which affects....
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This incredibly simple thermometer plugs on any free serial port. Does not make use of any programmable components as microcontrollers. It gives temperature readings accurate to 0.5°C with no calibration. It's cheap, so I've put one on any PC I use. And it....
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A unified thermometric controller that can be programmed with simple scripts, integrating the "classic" thermometer/controller pair. You can build a variety of simple machines with the same hardware and a different script : a charting thermometer, a vending....
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Here is a circuit that implements phase-control of heaters, adjusting their power smoothly from zero to around 95% of the rated power, keeping the room temperature to within 1 or 2 degrees, while using few components. Notice that this is entirely an AC....
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This circuit uses a germanium diode (marked Ge) as a temperature sensor. I used an OA90 diode but others should do. The 'ring' of Tr1 and Tr2 bias each other. Tr1's collector current is stabilized by the 5v6 zener, causing Tr2 to operate at about 5mA: this....
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This circuit greatly expands upon the capabilities of circuit 02. A thermocouple signal is quite small, and the long thermocouple leads often induce quite a bit of noise into the system. This new circuit is far more accurate, stable, and less immune to....
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Continuing with the thermocouple interface concept, the next step is to amplify the TC's millivolt signal into a more readable analog voltage, on the order of 0 to 5VDC. This simple circuit fits the bill. The LM358N is a dual op-amp IC. I'm quite sure any....
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This LED thermometer is designed for in home use, to read temperatures between about 60 and 78 degrees Fahrenheit. It is based around a precision temperature sensor IC, the LM34DZ. This sensor require no calibration and can measure temperatures of between....
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A device designed for measuring time and temperature used in chemistry laboratory. The circuit employs a 89C4051, 20-pin CMOS Microcontroller with built-in 4kB code memory. Temperature was measured by LM35D, National Semiconductor Temperature sensor....