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potentiometer in electronics
Post Date：2024-05-18，
potentiometer in electronics
Potentiometer is an instrument constructed by compensation principle. A high precision measuring instrument based on the principle that measured voltage and known voltage compensate each other. Divided into AC, DC two. Used to measure voltage, current and resistance, AC potentiometers also measure magnetism.
Also known as potentiometer, potentiometer. A high-precision instrument for measuring potential difference based on the principle that the measured voltage and the known voltage compensate each other (i.e. balance). Compared with the voltmeter, the main advantage is that the measurement does not require the circuit to be measured to supply current, so it does not affect the circuit to be measured, and can accurately measure the electromotive force of the power supply. Generally there are two kinds of rotating handle and sliding line.
Due to the potential compensation method, the measurement accuracy is high. The error caused by the internal resistance of the power supply is avoided, and the terminal voltage is measured without current passing through the power supply, which greatly improves the accuracy and sensitivity
The characteristic of the compensation method is that it does not draw current from the measuring object, so it does not interfere with the measured value, the measurement results are accurate and reliable, the potentiometer is very widely used, with standard batteries, standard resistors and other appliances, not only can measure the electromotive force, potential difference (voltage), current, resistance and other electrical quantities in the occasions with high accuracy requirements, but also with various transducers. It can also be used for temperature, displacement and other non-electric measurement and control.
Potential difference scoring AC and DC, widely used in production and scientific research. For example, when producing semiconductor materials and components, a thermocouple composed of platinum-platinum-rhodium alloy is commonly used to measure the furnace temperature, and the change in thermoelectromotive force is only tens of microvolts, which is not suitable for voltmeter measurement, and potentiometer is generally used. Potentiometers are also used to accurately measure current and resistance. Ac potentiometer can be used for magnetic measurement.
There are many kinds of potentiometer, common traditional potentiometer, digital potentiometer
Traditional potentiometer
Potential difference score DC potential difference meter and AC potential difference meter. The DC potentiometer is used to measure the DC voltage and adjust the size of the standard voltage to achieve the compensation of the two voltages. Ac potentiometer is used to measure sinusoidal AC voltage from power frequency to audio frequency. When two sinusoidal AC voltages of the same frequency are equal, their amplitude and phase are required to be equal, so the circuit of the AC potentiometer is more complex, and there are at least two adjustable quantities. Ac potentiometer in the market only for power frequency products, other frequencies of AC potentiometer are required to design their own production. With the continuous development and improvement of the theory and technology of DC current comparator, a high accuracy DC current comparator potentiometer has appeared, and its measuring error is about one millionth of an order of magnitude.
When calibrating an ammeter with a potentiometer, the voltage on the standard resistance is converted into a standard current by measuring it with a potentiometer, and then the ammeter is calibrated at each point. Estimate the error of the meter calibration device, and judge whether it is less than 1/3 of the basic error limit of the meter, and then draw the conclusion whether the calibration device is reasonable. When estimating, only the basic error limit of the potentiometer and the error of the standard resistance are required to be considered, which can be determined by the following formula:
Obviously, the error of the meter calibration device should also include the influence of other factors such as the undercalibration of the standard electromotive force, the fluctuation of the working current, and the poor insulation between the lines, but considering these factors is too complicated for the teaching experiment. The uncertainty of voltage measured by potentiometer in the formula is estimated by the above formula (5.8.1); The uncertainty of the standard resistance (in this experiment) can be simplified by the following equation
Digital potentiometer
Digital potentiometer/electronic potentiometer Model: tx-YJ108B/1
TX-YJ108B/1 type digital potentiometer is the replacement of traditional DC potentiometer products, it uses advanced digital, intelligent technology combined with traditional technology, in the use of functions completely cover the original potentiometer UJ33a, UJ33A-1 and other products, It can accurately detect millivolt signals output by thermocouples, sensors, transmitters and other primary instruments, and can also be used as a standard millivolt signal source to directly verify a variety of transmitters and instruments.
Product features: digital direct reading generation (output) and measurement (input) voltage values; The output standard voltage signal can be loaded, and all kinds of low impedance instruments can be checked directly. The four-end button is adopted to eliminate the error of measuring wire when the small signal is output. The millivolt value corresponding to the common temperature range of a variety of thermocouple indexes can be generated, and the temperature is displayed in direct reading; With precision reference source, remove the standard battery, avoid environmental pollution, and avoid repeated requirements on the standard, convenient for users to operate; With RS232 standard interface, can communicate with the computer; Dimensions: 88×215×285mm
In 1893, British scientists produced the first commercial potentiometer, the entire size of the potentiometer was reduced to about 1m, and the operation of the instrument was greatly reduced because of a selector switch and N-pair contacts. The circuit of this instrument is shown in Figure 9. They divided the resistance wire of the potentiometer into 15 parts, wound 14 parts into a helix, and the remaining part served as the slip wire itself. The helix is divided into 14 parts, each of which matches the slide resistance exactly. In this way, the errors caused by the non-uniformity of the wire and the errors caused by the wear effect of sliding contact on it are greatly reduced. Two current adjusting resistors are connected in series in the potentiometer circuit, one as a coarse adjustment and the other as a fine adjustment, according to which the standardized balance can be accomplished quickly and accurately.
Potentiometer is an instrument constructed by compensation principle. A high precision measuring instrument based on the principle that measured voltage and known voltage compensate each other. Divided into AC, DC two. Used to measure voltage, current and resistance, AC potentiometers also measure magnetism.
Also known as potentiometer, potentiometer. A high-precision instrument for measuring potential difference based on the principle that the measured voltage and the known voltage compensate each other (i.e. balance). Compared with the voltmeter, the main advantage is that the measurement does not require the circuit to be measured to supply current, so it does not affect the circuit to be measured, and can accurately measure the electromotive force of the power supply. Generally there are two kinds of rotating handle and sliding line.
Due to the potential compensation method, the measurement accuracy is high. The error caused by the internal resistance of the power supply is avoided, and the terminal voltage is measured without current passing through the power supply, which greatly improves the accuracy and sensitivity
The characteristic of the compensation method is that it does not draw current from the measuring object, so it does not interfere with the measured value, the measurement results are accurate and reliable, the potentiometer is very widely used, with standard batteries, standard resistors and other appliances, not only can measure the electromotive force, potential difference (voltage), current, resistance and other electrical quantities in the occasions with high accuracy requirements, but also with various transducers. It can also be used for temperature, displacement and other non-electric measurement and control.
how does a potentiometer work
When no current flows, the potential difference between the positive and negative electrodes of the battery is equal to the electromotive force of the battery. If there is a current flowing, because there is a certain voltage drop on the internal resistance of the battery (using a voltmeter to measure the voltage between the two poles of the battery, this is the case), then the measured electromotive force is no longer the battery, but can only be called the end voltage. If the measurement can be made when no current is flowing, the electromotive force can be measured directly. Compensation is one such method.Potential difference scoring AC and DC, widely used in production and scientific research. For example, when producing semiconductor materials and components, a thermocouple composed of platinum-platinum-rhodium alloy is commonly used to measure the furnace temperature, and the change in thermoelectromotive force is only tens of microvolts, which is not suitable for voltmeter measurement, and potentiometer is generally used. Potentiometers are also used to accurately measure current and resistance. Ac potentiometer can be used for magnetic measurement.
potentiometer classification
There are many kinds of potentiometer, common traditional potentiometer, digital potentiometer
Traditional potentiometer
Potential difference score DC potential difference meter and AC potential difference meter. The DC potentiometer is used to measure the DC voltage and adjust the size of the standard voltage to achieve the compensation of the two voltages. Ac potentiometer is used to measure sinusoidal AC voltage from power frequency to audio frequency. When two sinusoidal AC voltages of the same frequency are equal, their amplitude and phase are required to be equal, so the circuit of the AC potentiometer is more complex, and there are at least two adjustable quantities. Ac potentiometer in the market only for power frequency products, other frequencies of AC potentiometer are required to design their own production. With the continuous development and improvement of the theory and technology of DC current comparator, a high accuracy DC current comparator potentiometer has appeared, and its measuring error is about one millionth of an order of magnitude.
When calibrating an ammeter with a potentiometer, the voltage on the standard resistance is converted into a standard current by measuring it with a potentiometer, and then the ammeter is calibrated at each point. Estimate the error of the meter calibration device, and judge whether it is less than 1/3 of the basic error limit of the meter, and then draw the conclusion whether the calibration device is reasonable. When estimating, only the basic error limit of the potentiometer and the error of the standard resistance are required to be considered, which can be determined by the following formula:
Obviously, the error of the meter calibration device should also include the influence of other factors such as the undercalibration of the standard electromotive force, the fluctuation of the working current, and the poor insulation between the lines, but considering these factors is too complicated for the teaching experiment. The uncertainty of voltage measured by potentiometer in the formula is estimated by the above formula (5.8.1); The uncertainty of the standard resistance (in this experiment) can be simplified by the following equation
Digital potentiometer
Digital potentiometer/electronic potentiometer Model: tx-YJ108B/1
TX-YJ108B/1 type digital potentiometer is the replacement of traditional DC potentiometer products, it uses advanced digital, intelligent technology combined with traditional technology, in the use of functions completely cover the original potentiometer UJ33a, UJ33A-1 and other products, It can accurately detect millivolt signals output by thermocouples, sensors, transmitters and other primary instruments, and can also be used as a standard millivolt signal source to directly verify a variety of transmitters and instruments.
Product features: digital direct reading generation (output) and measurement (input) voltage values; The output standard voltage signal can be loaded, and all kinds of low impedance instruments can be checked directly. The four-end button is adopted to eliminate the error of measuring wire when the small signal is output. The millivolt value corresponding to the common temperature range of a variety of thermocouple indexes can be generated, and the temperature is displayed in direct reading; With precision reference source, remove the standard battery, avoid environmental pollution, and avoid repeated requirements on the standard, convenient for users to operate; With RS232 standard interface, can communicate with the computer; Dimensions: 88×215×285mm
In 1893, British scientists produced the first commercial potentiometer, the entire size of the potentiometer was reduced to about 1m, and the operation of the instrument was greatly reduced because of a selector switch and N-pair contacts. The circuit of this instrument is shown in Figure 9. They divided the resistance wire of the potentiometer into 15 parts, wound 14 parts into a helix, and the remaining part served as the slip wire itself. The helix is divided into 14 parts, each of which matches the slide resistance exactly. In this way, the errors caused by the non-uniformity of the wire and the errors caused by the wear effect of sliding contact on it are greatly reduced. Two current adjusting resistors are connected in series in the potentiometer circuit, one as a coarse adjustment and the other as a fine adjustment, according to which the standardized balance can be accomplished quickly and accurately.
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