A Pyrometer Is A Non Contacting Device

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A pyrometer is a non-contacting device that intercepts and measures thermal of a radiation, a process known as pyrometer. Its a device that can be used to determine the temperature of an objects surface. It has an optical system and a detector. The optical system can focuses thermal radiation onto the detector. The output signal of the detector is related to the thermal radiation or irradiance j* of the target object through the Stefan-Boltzmann lam, the constant of proportionality  σ, called the Stefan-Boltzmann constant and the emissivity ε of the object

j^{\star} = \varepsilon\sigma T^{4}

This output of the pyrometer is to used to infer object's temperature. There is no need for direct contact the between pyrometer and the object, as there is with thermocouples and resistance detectors (RTDs).


Radiation pyrometer

The radiation pyrometer is the body or the fluid is emitted of the temperature is to be measured and also to focused on a thermal receiving surface, it is usually in the foam of a very thin strip of blackened platinum also the changes in temperature of this surface is measured. Thus in a radiation thermopile a large number of thermocouple in the form of strip are connected in the series and also arranger side by side so that all the not junction which are blackened to increase the energy, when it absorbing ability the pyrometer also fall within a very small target area. The thermoelectric characteristics of the thermopile are very stable because the thermocouple are rarely connected directly to the furnace and also not present at a temperature of more than a few hundred degrees. The thermopile has more advantage over other detectors, and also give the same response to incoming radiation in the range of 0.3-20µm irrespective of wavelength within the range. The calibration of a total radiation pyrometer is done with black body radiation. For example the output temperature T4 since the pyrometer is use to measure the temperature of a fluid or a hot body, the emission is not correctly known, then the temperature that measured will not be corrected and some degree of error will be present. The error are calculated and some degree of error will be present. The error are calculated as the output thermometer temperature is directly proportional to T4.

E = KЄT4

The 'K' is a constant by differentiating we will get : DT/T = dЄ/4Є

10% of the error in the value of emission will result in 2.5% error in the temperature of the radiant object that is measured

Pyrometric cone


It's the device that rarely used to gauge heat work during the firing of ceramic materials. The cones, often used in sets three as shown in the illustration, are positioned in a kiln with the wares to be fired and provide a visual indication of when the wares have reached a required state of maturity, a combination of time and temperature. Thus, pyrometric cones give a temperature equivalent and also are not simple temperature-measuring devices.

Resistance thermometer


Resistance thermometer also called resistance temperature detector (RTDs) are sensors used to measured temperature by collating the resistance of the RTD element with temperature. Most RTD element consist of a length of fine coiled wire wrapped around made from a pure material, platinum, nickel or copper. The material has a predictable change in resistance as the temperature changes.


File:Thermometer CF.svg

The thermometer is mainly used to measure the temperature of the body. The other uses are a pendulum can be constructed from a thermometer attached to a light string by which approximate gravitational acceleration could be calculated and by measuring time needed for a thermometer released from the top of a building to hit the ground, in this way, approximate height of that building could be obtained. Apart from it max thermometer and min thermometer are used to measure air temperature



Electrocardiogram (ECG)

There are several precision amplifier and instrumentation amplifier opportunities in ECG application. The diagnosis is in a (clinical) ECG with up to 12 leads. Key block lead devices are the electrode gain amplifier, high-pass filter (usually 0.5 Hz), low-pass filter (around 150 Hz) and right-led drive circuit. Each electrode required a precision instrumentation amp to extract a very small signal that rides on a 300 mV to 700 mV common-mode voltage.

Typically, this amplifier will use a higher supply voltage to enable a high gain without railing the amplifier in the presence of the common-mode voltage from the body. This amp can be a discrete instrumentation amplifier or an integrated instrumentation amplifier. Second and third stage active-filter amplifiers are needed to set a very specific band (0.5 Hz - 150 Hz) to capture the electrocardiogram wave signal. Basically these will be low noise, 5V amplifier with good appropriate bandwidth. In addition, low-noise, low-power amplifier are needed for the right-leg-drive feedback function.

In multi-channel from system, it usually is a 12-lead ECG monitor will be using for a common users, it is to multiplex signal into a common ADC system. The key typical requirements for the multiplexer (mux) are low on-resistance and low charge injection on the system.

Generally a specific mux is selected to match the voltage requirements of the filter amplifier and the ADC. It is also common for multichannel ECGs to have automated lead detection to enable multi-configuration operations. Generally, a low on-resistance switch is used in this circuit as well

Multiplexers like the ISL43681 and ISL43640 series are excellent choices for medical devices as they can operate a range from 2V to 12V. In addition, they have low-on resistance of 39 to 60 Ω, which lower distortion and reduces 'kick-back' voltage from the system. Their low charge injection of 0.3 pC (picocoulombs) reduces error contribution on charge-redistribution on a ACDs system.

For 3-lead portable ECG application, low-power instrumentation amps from a CMOS process may be a better selection on the multiplexers. Since CMOS inputs naturally provide a high-impedance input, the need for external is eliminated, saving cost. A good choice for the input amplifier can deliver active feedback with a very precise base line compensation voltage, low 1/f noise, extremely low offset, and low drift versus temperature.

What (electrically) is being measured?

It is electrical activity of the heart muscle as it changes with time, usually printed on paper for easier analysis. Like other muscles, cardiac muscle contracts in response to electrical depolarisation of the muscle cells. It is the sum of this electrical activity, when amplified and recorded for just a few seconds that we know as an ECG.

How is the electrical signal capture?

A signal-averaged electrocardiogram is a more detailed type of ECG. During this procedure, multiple ECG tracings are obtained over a period of approximately 20 minutes evaluating several hundred cardiac cycles to detect subtle abnormalities that increase risk for cardiac arrhythmias. These subtle abnormalities are usually not detected on a plain ECG. A computer captures all the electrically signal from the heart and averages them to provide the doctor detail regarding how the heart's electrical conduction system is working and shown on the ECG system. It show a radar on the system, it's a heart-beat frequency rate.


Complete circuit of a functional block diagram (ECG)


Voltage to frequency

From the basic of voltage to frequency the LM231/LM331 converters ideally suited for in simple low cost circuit from analog to digital conversion, the precision frequency to voltage conversion, long-term integration, linear frequency modulation or demodulation, and many other function. The output when used a voltage to frequency converter is a pulse train at a frequency precisely proportional to the applied input voltage. The conversion of voltage to frequency it provides all the inherent advantages of the voltage to frequency converter techniques, and easy to apply in all standard voltage to frequency converter application. Further, the LM231A/LM331A series attained a new high level of accuracy versus temperature which could be attained with expensive voltage to frequency modules. The LM231/331 are ideally suited for use in digital system at low power supply voltages and can provide low-cost analog to digital conversion converter can be easily channeled through a simple photo isolator to provide isolation against common levels

The LM231/LM331 utilize a new temperature-compensated band-gap reference circuit, to provide excellent accuracy over the full operating temperature range, at power supplies as low as 4.0V. the precision timer circuit has low bias currents without degrading the quick response necessary for 100kHz voltage-to-frequency conversion. And the output are driving 3 TTL loads, or a high voltage output to 40V, yet is short-circuit against Vcc.

Frequency to voltage

The LM 2907/LM 2917 series are frequency to voltage converter with a high gain op amp or comparator designed to operate a relay, lamp, or other load when the input of frequency reached are exceeds a selected rate. Most of the tachometer uses a charge pump technique and offer frequency doubling for low ripple and full input protection in two versions (LM2907-8, LM2917-8) or output swing to ground for a zero frequency input.

The op amp or comparator is fully compatible and the tachometer has a floating transistor as its output from the frequency. This feature allows either a ground or supply referred load up to 50mA. The collector may be taken above Vcc up to a maximum VCE of 28V.

The identical basic configurations include an 8-pin device with a below referenced tachometer input and its internal connection between the tachometer output and the op amp non-inverting input. This version is well suited for single speed, either double speed or frequency switching or fully buffered frequency to voltage conversion application.

The more frequency is configure and provide a differential tachometer input and uncommitted op amp inputs. With this version the tachometer input may be floated and the op amp become suitable for active filter conditioning of the tachometer output.


Differential pressure flow measurement is reliable with the aid of microprocessor technology discharge coefficient can be stored on the instrument and measuring temperature absolute pressure allows to correct fluid parameter such as density and velocity to obtain the mass flow rate. This are called multivariable mass flow meters. The origin of differential pressure flow measurement is the Bernoulli equation represent energy conservation for a fluid element

Orifice plate

Orifice plates are most commonly used for continuous measurement of fluid in pipes. They are also used in some small river system to measure flow rate at locations where the river passes through a culvert or drain. Only a small number of rivers are appropriate for the use of the technology since the plate must remain completely immersed i.e. the approach pipe must be full, and the river must be substantially free of debris.

In the natural environment, large orifice plates are used to control onward flow in flood relief dams. In these structure a low dam is placed across a river and in normal operation the water flows through the orifice plate unimpeded as the orifice is substantially large than the normal flow cross section. However in flood, the flow rate rises and floods out the orifice plate which can then only pass flow determined the physical dimension of the orifice. Flow then held back behind the low dam in a temporary reservoir which is slowly discharged through the orifice when the flood subsides


The Bernoulli principle and its corollary, the venture effect, are essential to aerodynamic as well as hydrodynamic design concept. Airflow and hydrofoil designs to lift and steer air and water vessels (airplanes, ships and submarines) are derived from application of the Bernoulli principle and the venture effect, as are the instruments that measure rate of movement through the air or water (velocity indicator). Stability indication and control mechanisms such as gyroscopic attitude indicators and fuel metering devices, such as carburetors, function as a result of gas fluid pressure differentials that create suction as demonstrated and measurable by gas/fluid pressure and velocity equation from the Bernoulli principle and the venture effect.


A nozzle us a device to control the direction or characteristics of a fluid flow (especially to increase velocity) as it exist (or enters) an enclosed chamber or pipe via an orifice. A nozzle is often a pipe tube of varying cross sectional area, and it can be used to direct or modify the flow of a fluid (liquid or gas). Nozzles are frequently used to control the rate flow, speed, direction, mass, shape, or the pressure of the stream that emerges from them

Pilot tube

The basic pilot tube consists of a tube pointing directly into the fluid. As this tube contain fluid, a pressure can be measured, the moving fluid is brought to rest (stagnates) as there is no outlet to allow flow to continue. This pressure is the stagnation pressure of the fluid, also known as the total pressure or (particularly in aviation) the pilot pressure