How to measure a potentiometer, how to measure a potentiometer with a multimeter

It is judged by the method of appearance and manual adjustment.

The detection potentiometer is judged by the method of appearance and manual adjustment.

First, the preliminary method of observation is adopted.

Take a visual look. Turn the rotary handle, check whether the rotation of the rotary handle is smooth, whether the switch is flexible, whether the "click" sound is crisp when the switch is on and off, and listen to the sound of friction between the internal contact point and the resistor of the potentiometer, if there is a loud "rustle" sound or other noise, it means that the quality is not good. In general, the rotary shank should be slightly dampened when turning, neither too "dead" nor too flexible.

With the help of a multimeter.

When judging the use of a multimeter to measure a potentiometer, you should first select the appropriate ohm of the multimeter according to the nominal resistance of the potentiometer to be measured.

gear is then measured. When measuring, the red and black pens of the multimeter are respectively touched to the fixed pins, that is, the pins on both sides, and the reading of the multimeter should be the nominal resistance of the potentiometer.

If the multimeter reading differs significantly from the nominal resistance, the potentiometer is damaged. When the nominal resistance of the potentiometer is normal, the change resistance value and whether the contact between the movable contact and the resistor body fixed contact are good.

Method of measuring potentiometer:

1. Detection of nominal resistance.

When measuring, use a multimeter.

The appropriate range of the resistance range, connect the two meter pens between the two fixed pin solder lugs of the potentiometer respectively, and measure whether the total resistance of the potentiometer is the same as the nominal resistance value. If the measured resistance is infinity.

or higher than the nominal resistance, it means that the potentiometer has been opened or the variable value is damaged. Then connect the two surface hairs to either end of the center head of the potentiometer and the two fixed ends respectively, slowly rotate the potentiometer handle to rotate it from one extreme position to the other extreme position, the resistance value indicated by the normal potentiometer and the multimeter gauge hand should change continuously from the nominal resistance value (or 0) to 0 (or the nominal resistance value). During the entire rotation, the watch hand should change smoothly without any run-out.

If the watch hand jumps in the process of adjusting the resistance value, it means that the potentiometer has a poor contact fault.

The detection method is the same for slide potentiometers.

2. Detection with switching potentiometer.

For potentiometers with switches, in addition to testing the nominal resistance and contact of the potentiometer according to the above methods, the switch should also be tested to see if the switch is normal. Rotate the potentiometer shaft handle first, check whether the switch is flexible, and whether there is a crisp "click" sound when turning on and off. With the multimeter R 1 gear, the two meter pens are respectively on the two external solder tabs of the potentiometer switch, rotate the potentiometer shaft handle, so that the switch is turned on, and the resistance value indicated on the multimeter should change from infinity ( ) to 0.

Turn off the switch again, and the multimeter pointer should return from 0 to the " ". During the measurement, the potentiometer switch should be turned on and off repeatedly, and the response of each action of the switch should be observed. If the resistance of the switch is not 0 at the "on" position and infinity at the "off" position, the switch of the potentiometer is damaged.

3. Detection of double-coupled axial potentiometer.

Use the appropriate range of the resistance file of the multimeter to measure whether the resistance values of the two sets of potentiometers on the double potentiometer (i.e., the resistance values between a and c and the resistance values between a' and c') are the same and whether they are consistent with the nominal resistance values. Then use the wire to short-circuit the potentiometer A, C' and the potentiometer A', C respectively, and then use a multimeter to measure the resistance value between the center head B, B', in an ideal situation, no matter what position the shaft of the potentiometer turns, the resistance value between the two points of B and B' should be equal to the resistance value between A, C or A', C' (that is, the multimeter pointer should always be kept on the scale of A, C or A', C' resistance value). If the multimeter pointer is deflected, it means that the potentiometer has poor synchronization performance.

How is a potentiometer measured? How can you quickly tell if it's good or bad? It turns out that the method is so simple.

<>1. Check the potentiometer.

, first turn the handle, try to see if the handle rotates smoothly and whether the switch is flexible. Whether the "click" sound is crisp when the switch is on and off, and listen to the sound of friction between the internal contact point and the resistor body of the potentiometer, if there is a "rustle" sound, it means that the quality is not good;

2. Use a multimeter.

During the test, first select the appropriate resistor position of the multimeter according to the resistance value of the potentiometer to be measured. Use the resistor of the multimeter to measure the two ends of "1" and "3", and its reading should be the nominal resistance value of the potentiometer, if the pointer of the multimeter does not move or the resistance value is very different, it indicates that the teasing potentiometer has been damaged;

3. Check whether the contact between the movable arm of the potentiometer and the resistor plate is good. Use the resistor of the multimeter to measure the two ends of "1" and "2", and rotate the rotating shaft 2 of the potentiometer in the counterclockwise direction to the position close to "off", and the smaller the resistance value is, the better. Clockwise again.

Slowly rotate the shaft shank, the resistance value should gradually increase the gauge head.

The pointer in should move this or move smoothly. When the shaft handle is rotated to the extreme position "3", the resistance value should be close to the nominal value of the potentiometer. Test experience: If the pointer of the multimeter jumps during the rotation of the shaft handle of the potentiometer, it means that the movable contact has a fault of poor contact.

The measurement reference is different: the potential is the potential based on the earth or the common reference point of the circuit, and the voltage is the potential between two points in the link; The potential has a definite direction (positive and negative) with respect to a common reference point, and the voltage theoretically has no negative value.

Problems that should be paid attention to when measuring current and voltageIn electrical circuits, circuits and voltages are the most basic quantities. There are two types of circuits: DC and AC, so there are also two types of current and voltage: DC current, AC current and DC voltage, and AC voltage. An instrument that is specifically used to measure current is called an ammeter.

A meter that is specifically used to measure voltage is called a voltmeter.

When measuring current and voltage, the following three issues should be noted.

1. The ammeter must be connected in series with the electrical equipment, and the voltmeter must be connected in parallel with the electrical equipment.

2. According to the size to be measured, select the appropriate range. The measuring range is too large and the measurement is not accurate; The measuring range is too small, and it is easy to burn out the instrument. If the measurement size cannot be estimated, you can select the maximum range first, and then adjust it to the appropriate range according to the deflection of the pointer.

3. Pay attention to the polarity of the instrument in the measurement of DC, measure the DC current, and the wiring should make the current flow in from the positive pole of the meter and the negative electrode to the imitation flow; To measure the DC voltage, the positive pole of the meter should be connected to the high potential end, and the negative end should be connected to the low potential end. After a current transformer.

The circuit that measures the single-phase current is in an AC circuit.

If the current to be measured is large, or the voltage of the measured circuit is higher than that of Jingla, the current transformer and the AC ammeter with a range of 5A can be used to measure the current, which is to expand the range of the ammeter, and it is also safer. The wiring of the circuit shows the measurement circuit on the left, which we usually use with an AC ammeter.

The current measurement circuit diagram is performed directly in series with a current transformer on the right.

A potentiometer is essentially a variable resistor. Take a 47K potentiometer as an example: its A, B, C, solder lug output points, B is the midpoint, and the resistance values of points A to B and C to B points are all 47K, but the direction of change is opposite.

Use the meter to hit the r*1k block, measure the a, b and c, b points, and the resistance value is 47k. The more uniform the change in resistance from small to large, the better. The resistance value of point A and C is 47K, which does not change.

Compliance is qualified.

First, measure the resistance between the two fixed plates, and between the measuring moving plates, the resistance value of the sliding potentiometer should change evenly.

Potentiometer measurements.

1. Measurement of the nominal resistance value of the potentiometer.

The potentiometer has 3 lead tabs: two end tabs and a center tap contact. When measuring its nominal resistance, select the appropriate range of the multimeter ohm, put the two meter pens of the multimeter on the two end pieces of the potentiometer, and the resistance value pointed by the multimeter pointer is the nominal resistance value of the potentiometer.

2. Performance measurement.

Performance measurement measures whether the center tap contact of the potentiometer is in good contact with the resistor.

When measuring, screw the center contact of the potentiometer to either end of the potentiometer, select the appropriate range of the multimeter ohm, put one meter pen of the multimeter on any piece of the mess at both ends of the potentiometer, and put the other meter pen on the center tap contact of the potentiometer.

At this point, the reading on the multimeter should be either nominal or 0 for the potentiometer.

Then slowly rotate the knob of the potentiometer to the other end, and the multimeter reading will continue to decrease from the nominal value or rise continuously from 0 as the turn of the potentiometer knob until it falls to zero or rises to the nominal resistance value.

Method of measuring potentiometer:

1. Detection of nominal resistance. When measuring, select the appropriate range of the resistance file of the multimeter, connect the two meter pens between the two fixed pin solder lugs of the potentiometer respectively, and measure whether the total resistance value of the potentiometer is the same as the nominal resistance value. If the measured resistance is infinity or greater than the nominal resistance, the detection method for the slide potentiometer is the same.

2. For the potentiometer with switch, in addition to detecting the nominal resistance and contact of the potentiometer according to the above methods, the switch should also be tested whether the switch is normal. Rotate the potentiometer shaft handle first to check whether the switch is flexible. When measuring, the potentiometer switch should be repeatedly turned on and off, and the resistance value at the "off" position is not the base infinity, which means that the switch of the potentiometer has been damaged.

3. Detection of double-connected potentiometer Use the appropriate range of the resistance file of the multi-purpose spike to measure whether the resistance value of the two groups of potentiometers on the double-connected potentiometer is the same and whether it is consistent with the nominal resistance value. Ideally, the value of resistance between two points should be equal to the value of resistance between two non-adjacent points, regardless of the position of the potentiometer's shaft. If the multimeter pointer is deflected, it means that the potentiometer has poor synchronization performance.

The principle is that when the brush moves along the resistive body, the resistance value or voltage that has a certain relationship with the displacement is obtained at the outlet of the transmission body.

1. According to the size of the resistance value of the potentiometer to be measured, select the appropriate resistance level of the multimeter, measure the resistance value between the two fixed end pieces and compare it with the nominal resistance value; Rotate the sliding contact, the value of which should be fixed. If the resistance is infinite, then this potentiometer is damaged.

2. The ohmic crack punching cavity of the multimeter is in the appropriate range, and the sliding contact in the middle is slowly rotated, and the reading changes smoothly in one direction under normal circumstances; If there is a phenomenon such as jumping, falling or not working, it means that the movable contact has a fault of poor contact.

3. When the center end slides to the first end or the end, the resistance value of the center end and the coincident end is 0 in the ideal state, but there will be a certain residual value in the actual measurement, which is generally less than 5, which is judged to be a normal phenomenon.

The potentiometer is a resistive element composed of a resistive body, two fixed end pieces and a movable brush, and the resistance value can be adjusted according to a certain change law.