Emf meter circuit diagram pdf,the book of revelation the apocalypse 894,earthquake relief kit hoax - Step 3

The output signal from the op-amp is an ac voltage at the frequency of the electro-magnetic field. If you have access to an audio signal generator you can apply an audio signal to the windings of a small transformer. Estimated delivery dates - opens in a new window or tab include seller's handling time, origin ZIP Code, destination ZIP Code and time of acceptance and will depend on shipping service selected and receipt of cleared payment - opens in a new window or tab. International Shipping - items may be subject to customs processing depending on the item's declared value. Your country's customs office can offer more details, or visit eBay's page on international trade. By clicking Confirm bid, you commit to buy this item from the seller if you are the winning bidder. By clicking Confirm bid, you are committing to buy this item from the seller if you are the winning bidder and have read and agree to the Global Shipping Program terms and conditions - opens in a new window or tab. By clicking 1 Click Bid, you commit to buy this item from the seller if you're the winning bidder. This is a private listing and your identity will not be disclosed to anyone except the seller. Thermowells are used for almost all applications except for some specific applications (that is, for very-low-pressure air systems, for ventilating systems, bearing temperature measurement, lube oil drain in compressor and so on) where faster response required or space limitation such as casing drain in compressor. The primary element has the necessary static and dynamic mechanical strength for the application. Either a failure of the element may be tolerated until the process can conveniently be shut down, or operation can continue without the use of the element. In case if test Thermowells are required, then devices with suitable plugs shall be provided. Standard Thermowells should be stamped with the ASTM material designation, “U” (insertion length) dimension, Rating and the tag number.
Thermowells installation shall be per Piping & Instrumentation Interface Diagram or as specified in the piping specification. In-case if Thermowells are installed in pipe lines which are less than 4”, then a section of this pipe line shall be expanded to 4”.
Thermowells can be installed in Tee at a 90-degree pipe elbow in case of smaller pipe sizes.
Thermowell insertion length should be sufficient to measure the bulk temperature of the fluid without conduction effect. If the Thermowell is installed at an angle or in an elbow, the tip should point toward the flow in the process line. Thermowells installed in lines through which fluid flows at a high velocity may be subject to vibration, which can rupture the well below the mounting. On Equipment or Vessels minimum immersion length should be between 300 to 500mm based on requirement.
While deciding insertion length, nozzle stand out, insulation thickness, pipe thickness etc shall be taken in account.
Special applications such as agitated vessels, separation columns, etc., with internals, may require shorter Thermowell lengths and should be checked for interference. Pipe insulation or lagging extension is the extra length provided between the Thermowell piping connection and the temperature element connection. Thermowell Flange Material Different than Pipe Material: In case, if material of construction (MOC) of Thermowell is different than the pipe class material, the flange rating of Thermowell shall be suitable and withstand pipe line design condition that is, pressure temperature.
Incase if the flange rating of Thermowell is different than the pipe rating, it should be communicated to Piping and Process to take necessary action at their end (provide nozzle with same rating as Thermowell rating). Requirement of Insulating Gasket shall be communicated to Mechanical & Process in case material of construction for Thermowell is different than piping material. In case if Thermowells are with collar to protect them from failure due to high vibration, the nozzle ID shall be checked with respective to collar diameter.
Care shall be taken when Thermowells are selected with collars for lined vessels & cladded vessels. Requirement of Thermowell connections (Flanged, Threaded or Welded) shall be checked as per specific project requirement.
Multipoint temperature elements (RTDs or Thermocouples) are used for tank gauging system & process reactors.
In the tank gauging system, the requirement is to measure fluid temperature at different level, which can be obtained by installing multipoint temperature elements assembly, which consist of number of elements of different length in one Thermowell.
In case of process reactors, the device made from pipe is used to installed 3 or 4 temperature element of different length (to measure temperature at different location on reactor diameter) to measure temperature of chemical bed at specific location. In some reactors requirement is to measure temperature of chemical bed at different location and different levels.
A resistance temperature detector (RTD) can also be called a resistance thermometer as the temperature measurement will be a measure of the output resistance. The main principle of operation of an RTD is that when the temperature of an object increases or decreases, the resistance also increases or decreases proportionally. Copper lead wires are satisfactory for all the arrangements.  For a given RTD, all the lead-wires should be of the same gauge and the same length, and should be run in the same conduit.
The four wire system is little affected by temperature induced resistance changes in lead-wires, and, of all the arrangements, it is affected least by stray currents.  It, therefore, is used to measure temperature differences and is used generally for making very accurate measurements.
The head shall be explosion proof where and as needed to conform to a hazardous area rating.  However, explosion proofing will not be required if the system is intrinsically safe. As discussed earlier, an Optical Pyrometer can be not only be used for temperature measurement, but also can be used to see the heat that is measured. The wavelengths measured by the device are known to be pure radiation wavelengths, that is, the common range for radioactive heat. The main theory behind a radiation pyrometer is that the temperature is measured through the naturally emitted heat radiation by the body.
Total Radiation Pyrometer – In this method, the total heat emitted from the hot source is measured at all wavelengths.
Selective Radiation Pyrometer – In this method, the heat radiated from the hot source is measured at a given wavelength.
As shown in the figure below, the radiation pyrometer has an optical system, including a lens, a mirror and an adjustable eye piece. The device can be used to measure very high temperatures without direct contact with the hot source (Molten metal). The sight path of the device is maintained by the construction of the instrument components, such as the lens and curved mirrors. So as to increase the temperature range which is to be measured, an absorption screen is fitted between the optical lens and the reference bulb. A red filter placed between the eye piece and the reference bulb helps in narrowing the band of wavelength. As long as the size of the object, whose temperature is to measured fits with the size of the optical pyrometer, the distance between both of them is not at all a problem. As the measurement is based on the light intensity, the device can be used only in applications with a minimum temperature of 700 degree Celsius.
The device is not useful for obtaining continuous values of temperatures at small intervals. A thermocouple is a temperature sensor that has a pair of dissimilar metals joined together at one end and terminated at the other end.
Thermocouple Type E    is a combination of Chromel (Nickel-Chromium) and Constantan (Copper-Nickel).
Thermocouple Type K    is a combination of Chromel (Nickel-Chromium) and Alumel (Nickel Aluminium).
Sometimes, a thermocouple has to be installed inside a Thermowell for providing protection. Clamp-on Thermocouples – As the name suggests they are clamped to a pipe, and thus presses the measuring junction against the pipe. The figure below shows a washer type thermocouple that is to be installed on the pipeline and temperature transmitter for this application.
Many types of clamp-on and surface thermocouples are present in the market and they are selected according to the requirement. Duplex Thermocouples – Duplex thermocouples are very similar to the conventional thermocouple except that this device has two pairs of thermocouple wires in the measuring junction. Thermocouple grounding should be done to the low- or negative-potential side of the circuit, and should be done at the source rather than at the secondary instrument in order to achieve maximum rejection of common-mode noise.  There is a normal practice that any electrical or electronic circuit should be grounded at only one point s as to avoid a ground current in the circuit. Unintentionally grounded – This is used in places where a bad contact or no contact of the measuring junction with a well occurs or because of formation of a high-resistance chemical film at the measuring junction.
PT:1    Interconnection of shield and thermocouple is not applicable if shield is not required. PT:3   Grounding the thermocouple may be done by connecting to the thermocouple head or junction box screw, assuming that these are grounded. PT:5   If the thermocouple, proper, is grounded, then the remainder of the circuit, from thermocouple to receiver, if any, shall not be grounded.
PT:6   If the secondary instrument is not a transmitter, but of a type, such as a recorder, that does not have a measurement output, then the output lines and associated  details on the diagram should  be ignored.
The device could be interfered by external noises from different sources like electrostatic fields, magnetic fields and common mode interference. The best way to minimize the interference of such electrostatic fields is to cover the thermocouple wires with a grounded metal shield. A varying magnetic field (such as the one produced by AC current in a power cable) may cause interference to thermocouple signals by generating small currents in the signal wire by induction.  The magnitude of the induced current is a function of the field strength and the dimensions of the conductive loop into which the current is being induced.


Common mode interference generates noise that is identical in both conductors of a twisted pair with respect to ground. Freedom of effect by wire length and diameter provided that a high-impedance secondary instrument is used.
Like a thermocouple, a thermopile is also a device that is used to measure temperature in terms of electrical energy. The device is capable of generating an output voltage, that will be a measure of the temperature difference or temperature gradient.
The device finds its application as a part of temperature sensors, like the infrared thermometer, a device used to calculate body temperature.
Thermistor is a resistance thermometer, similar to a Resistance Temperature Detector (RTD) and is used for temperature measurement. Both devices work on the same principle that a constant current flowing through the resistor, and its changing resistance due to change in temperature, is measured as a voltage drop across it.
The device is manufactured from materials like sintered mixtures of oxides of metals such as manganese, nickel, cobalt, and iron. The resistance versus temperature curve is one of the main characteristics that is used in measurement, control and compensation applications using a thermistor. From the characteristics graph of a typical thermistor, we can see that the resistivity changes from 107 to 1 ohm-cm as the temperature changes from -100 degree Celsius to +400 degree Celsius. For studying about the different types of thermistors, it is important to understand the formula which shows the linear relationship between resistance and temperature.
As a 1st order approximation, the change in resistance is equal to the 1st order temperature co-efficient of resistance times the change in temperature. If the value of temperature coefficient of resistance (k) is positive, an increase in temperature increases the resistance. NTC thermistors are used for temperature measurements (usually in a narrow span and low temperature ranges). NTC thermistors are used to measure and monitor batteries while they are kept for charging. Transducer have been devised which produce either changes in voltage or change in impedance whenever the temperature changes. The temperature sensor that uses change in resistance to measure temperature is called a resistance thermometer.
Before going into detail, it is important to know some of the basic temperature parameters and instrumentation systems. Range: The range of a temperature measuring device is the maximum and minimum temperature it can indicate, record, measure or transmit. Span: The difference between the maximum and minimum values of temperature in the calibrated range is called span.
This DIY magnetic field sensor circuit is very simple and can detect fixed magnetic fields or fields that are varying at an audio frequency.
Meter ME1 is connected between the output of IC2 and the potential divider and it therefore responds to the voltage difference between the two. A 6V battery supplies power to the magnetic field sensor circuit and the current consumption is only about 9mA.
When the unit is first switched on it is likely that the meter will be driven fully positive or negative.
Determine the value of unknown resistance with this marvelous virtual physics lab software.
Find out the unknown value of resistance of given wire with this marvellous virtual physics lab software. This item will be shipped through the Global Shipping Program and includes international tracking.
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Packaging should be the same as what is found in a retail store, unless the item is handmade or was packaged by the manufacturer in non-retail packaging, such as an unprinted box or plastic bag. Import charges previously quoted are subject to change if you increase you maximum bid amount. The location for a Thermowell should also be checked with respect to accessibility.  In particular, there should be sufficient space to allow removal of the Thermowell assembly. A Thermowell installed perpendicular or at a 45-degree angle to the pipe wall should have a minimum immersion length of 2” and a maximum distance of 5” from the wall of the pipe. Tapered stems and U lengths established by means of stress analysis are recommended for high velocity. For better accuracy in temperature measurement, Thermowells must have a smooth, shiny surface with no pitting and corrosion.
This extra length is provided to ensure the temperature element connection is located outside the insulation and for ease of temperature element installation or removal.
For example, if pipe class is Carbon Steel (CS) and MOC for Thermowell is SS316, then Instrument Engineer should check the rating required for Thermowell based on line design pressure & temperature. This information should be communicated to Mechanical to avoid any mismatch during installation. In these cases nozzle ID shall be checked with equipment drawings to avoid mismatch of Thermowell during installation. The purpose of these elements is to measure the temperature at different location or different levels.
The main difference between a RTD and a Thermistor is that the sensing element used in a RTD is a metal and a thermistor uses ceramic or polymer material.
Platinum, Nickel and Copper are the most commonly used sensing elements.  Platinum is considered the best as it has the widest temperature range. The three-wire system is generally satisfactory for industrial measurement using a secondary instrument that is remote, say, more than 3 meters distant from the RTD.  Although the error caused by temperature change in the leads is virtually eliminated in a 3-wire arrangement, a slight non-linearity in the resistance change is introduced with this scheme. A transmitter may be mounted either on an enclosed rack or locally.  A local transmitter may be mounted on a Thermowell and supplied with it as a complete assembly. The observer is actually able to calculate the infrared wavelength of the heat produced and also see the heat patterns by the object.
This device is used in places where physical contact temperature sensors like Thermocouple, RTD, and Thermistors would fail because of the high temperature of the source. The heat energy emitted from the hot body is passed on to the optical lens, which collects it and is focused on to the detector with the help of the mirror and eye piece arrangement.
The device actually tracks and measures the amount of heat that is radiated from an object. As a measure of the reference temperature, a color change with the growth in temperature is taken.
Thus, optical pyrometers can be used to measure and view wavelengths less than or equal to 0.65 microns. The joined end is called the sensing junction or hot junction and the terminated end is called the reference junction or cold junction. Ungrounded Junction – This junction has very minimum response time, but is known for its incredible electro-magnetic shielding properties. Grounded Junction – The response time of this is more than ungrounded junctions and also provides good shielding properties for most process applications.
This is applicable only in cases where the temperature of a fluid flowing inside a pipe is to be measured.
This method is applicable only in places where a temperature measurement is desired for which normal provision was not previously made.  This thermocouple may be useful in trouble-shooting a process. But, if either one of the two thermocouple circuits fail due to measuring junction problems or short circuit, the whole device will have to be replaced. Generally grounded thermocouple circuits are recommended for personnel safety, to reduce the effects of electrical noise and provide good thermal response characteristics. With this rule in mind, thermocouple grounding is carried out in one of the following ways – It is always good practice to ground the thermocouple measuring junction or ground the thermocouple elsewhere than at the measuring junction. Alternatively, if another ground exists, then the thermocouple, proper shall not be grounded.
Electrostatic fields originate from voltage sources that are capacitively coupled to the thermocouple extension wire. Twisted conductors are effective at reducing the induced currents by alternating the polarity of the induced current with each half twist to cancel out most of the induction. The device is actually a combination of a number of thermocouples in series or parallel connection.
The device consists of a bulk semiconductor device that acts as a resistor with a high and negative temperature co-efficient of resistance, sometimes as high as -6% per degree Celsius rise in temperature.
The main difference is that the electrical resistance of the resistor used in a thermistor varies in a non-linear manner with respect to temperature. Their resistances range from 0.4 ohms to 75 mega-ohms and they may be fabricated in wide variety of shapes and sizes. This high negative temperature coefficient of resistance makes thermistor an ideal temperature transducer. The thermistor is designed to have a resistance of 2 kilo-ohms at 25 degree Celsius and temperature coefficient of -4% per degree Celsius will bring a reduction of 80 ohms per degree Celsius change in temperature.
A change in temperature causes a change in the resistance if the thermistor and the corresponding micrometer current reading is noted.
Such a device can be called a Posistor or Positive Temperature Coefficient Thermistor (PTC).
The flow of current through the device causes a heat to build up due to its resistive property.


When a CRT monitor is turned on, an initial current reaches the PTC thermistor and degaussing coil. Thus classification is based on the method by which the electrodes are placed on the ceramic body.
Resistance thermometer can be further classified into Resistance Temperature Detectors (RTD) and Thermistor. The range should be decided in such a manner that the normal operating temperature is almost (50-70)% of the full scale with the maximum temperature range close to, but more than the upper range of scale. If audio rather than DC performance is of most importance it would be advisable to use TL071CP for IC2 and then reduce the output resistor from 33k to 27k. Do no use a 9V battery as this will result in the maximum supply voltage rating of IC1 being exceeded. With careful adjustments of Balance control VR1 it should be possible to zero the meter and placing the probe near any magnetized object should then produce a suitable response. If static electricity is about stationary charges, then current electricity is about moving or flowing charges. If you'd like to get the additional items you've selected to qualify for this offer, close this window and add these items to your cart.
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If you reside in an EU member state besides UK, import VAT on this purchase is not recoverable. These protection tubes are usually fabricated of ceramic materials and they are installed in high temperature flue gas and duct applications.  Protection tubes are also available made of Inconel and with their ends open in order to improve speed of response and heat transfer. This extra lagging extension length shall be taken into account while deciding Thermowell insertion length. As platinum is the most commonly used metal for making RTD’s, the device can also be called Platinum Resistance Thermometers (PRT’s).
The thermal heat radiates from the object to the optical system present inside the pyrometer. The device compares the brightness produced by the radiation of the object whose temperature is to be measured, with that of a reference temperature.
The observer watches the process through the eye piece and corrects it in such a manner that the reference lamp filament has a sharp focus and the filament is super-imposed on the temperature source image. But, a Radiation Pyrometer can be used for high heat applications and can measure wavelengths between 0.70 microns to 20 microns. The temperature at the reference junction is called reference temperature and is always maintained constant.  When the sensing junction and the reference junction are at different temperatures, a potential difference is obtained and this causes a flow of current in the circuit.
It is used mostly for the measurements on electrical equipment, but is usually suitable for many process applications as well. The output may not be so accurate unless the point of measurement and the surrounding area are well insulated from the outer environment. Ungrounded thermocouples should be considered for applications where equipments are likely to get damaged due to ground faults or lightening strikes particularly in tank farm areas. Varying electrostatic fields, usually originating from AC conductors, produce a capacitive current flowing through the coupling path to the signal conductors. They can also be used to produce electrical energy, that is, by dissipating the heat from electronic devices. Due to this property of high sensitivity (that is, huge resistance change for a small change in temperature), the thermistor is mainly applicable in precision temperature measurement, temperature control, and temperature compensation, especially in a lower temperature range of -100 degree Celsius to +300 degree Celsius.
The sensing element used in the thermistor is made up of either a ceramic or polymer, while RTD uses pure metals as its sensing element. Usually, the meter is calibrated in terms of temperature with 0.1 degree Celsius resolution. If the value of k is negative, an increase in temperature will decrease the resistance value.
Thus, if excessive current flows through the device, the device begins to heat up accordingly and thus increases its resistance. The PTC thermistor will be of large size and thus, the resistance of the device increases as the current flows in. This main category could be further divided depending on the different types of geometries, shapes and processing methods.
The minimum span is the smallest range that the manufacturer can accurately calibrate within the device’s range. Factors to be reviewed while choosing Thermowells are resistance to corrosion, flow induced vibrations, erosion, ease of installation, preferred installation point of Thermowell, insertion length, material, velocity considerations, lagging extension etc. This is why the radiation pyrometer is more useful, as it can be used to measure all temperatures of wavelengths between 0.70 microns and 20 microns. Though the latter is known for faster detection of fast moving objects, the former may be used for small scale applications. The optical system makes the thermal radiation into a better focus and passes it to the detector. The reference temperature is produced by a lamp whose brightness can be adjusted till its intensity becomes equal to the brightness of the source object. The observer starts changing the rheostat values and the current in the reference lamp changes. At this time, the current that flows in the reference lamp is measured, as its value is a measure of the temperature of the radiated light in the temperature source, when calibrated. The thermoelectric voltage produced is due to the different binding energies of the electrons to the metal ions.
Another type of the clamp-on thermocouple is the skin couple that is used mostly to measure furnace tube and reactor surface temperatures.
Furthermore, if one pair of a duplex thermocouple is used for checking, then there is a risk of shorting or grounding the other pair of wire. Alternatively thermistor may be in the form of disks and washers made by pressing thermistor material under high pressure into flat cylindrical shapes with diameter from 3 millimeters to 25 millimeters. As shown in the figure, a bridge circuit is also used so as to increase the thermistors sensitivity. If the temperature goes higher than 175 degree Celsius, the device jumps to a negative temperature coefficient region. One of the main categories that is most commonly used in the industries is the bead type thermistors.  According to the shape and manufacturing methods, bead thermistors can be again classified into Bare Beads, Glass Coated Beads, Ruggedized Beads, and Bead in glass Enclosures and many more.
As the resistance decreases, the usual operation of the circuit is restored and the high current flows through it without damaging other parts of the circuit. Once it is done user can use more then one unknown resistor and connect them in series or parallel connection and find out the value of combination and individual resistance. Thus, the heat energy is converted to its corresponding electrical signal by the detector and is sent to the output temperature display device. For an object, its light intensity always depends on the temperature of the object, whatever may be its wavelength. Skin couples can either be tack welded to the surface being measured (furnace tubes) or clamped on (reactor walls). Due to its high sensitivity, thermistors are used in narrow span measurements and low temperature ranges from -20 degree Celsius to +120 degree Celsius.
Washers may be stacked and placed in series or parallel to increase power disciplining capability. This creates such an effect that develops more resistance in the device, and limits the amount of voltage and current in the device.
The degaussing coil is necessary to decrease the continuous magnetic field in a smooth manner. PRT’s can also be used in unsuitable environments where it can reduce atmospheric metallic vapours and also catalizable vapours if the element is bare.  It can also be used in radioactive environments.
The biggest advantage of this device is that, unlike a Resistance Temperature Detector (RTD) and Thermocouple, there is no direct contact between the pyrometer and the object whose temperature is to be found out. After adjusting the temperature, the current passing through it is measured using a multimeter, as its value will be proportional to the temperature of the source when calibrated.
It is made from ceramic type materials and are known to have a very high resistance from a small change in temperature.
From this, we learn to calculate the power and energy consumed by a circuit and find realistic cost estimates that help you gain an appreciation for the cost of energy. In industrial applications, a PRT is known to measure temperatures as high as 1500 degree Fahrenheit while copper and Nickel can measure only to a maximum of 400 degree Fahrenheit. Dopant’s are also added to the material so that they show a semi-conductive behavior as well.
We learn techniques of drawing and solving unknowns in simple circuits using ohm’s law and the behavior of resistors in series and parallel. Until the device reaches that particular point, it shows a negative temperature co-efficient pattern in its resistance-temperature characteristics. You will also be expected to read resistance in ohms based on stripes using a key provided. After this point, it starts to show an increasing positive temperature coefficient of resistance. The main difference in the temperature-resistance curve between a silistor and switching PTC Thermistor is shown below.



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