Needless to say, multimeters can be said to be the most commonly used electronic measuring instruments for electricians, but choosing a digital multimeter or an analog (pointer) multimeter is a problem. Some people say that digital multimeters have gradually replaced analog multimeters, but many professional old electricians are still more accustomed to using analog multimeters. What is the difference between a digital multimeter and an analog multimeter? Which one works better?
Difference 1: Reading Display
First of all, the biggest difference between a digital multimeter and an analog multimeter is the Reading Display. The digital multimeter is a liquid crystal display with high resolution, which can basically eliminate parallax when reading data. Relatively speaking, the reading is convenient and accurate. In this regard, analog multimeters are incomparable, but analog multimeters also have their own unique advantages, that is, the instantaneous deflection of the pointer can very intuitively reflect the changes in the properties of the measured object.
Because the digital multimeter is measured and displayed in an intermittent manner, it is not convenient to observe the continuous change process of the measured power and its changing trend. For example, digital multimeters are not as convenient and intuitive as analog multimeters to check the charging process of capacitors, the thermistor resistance changes with temperature, and observe the characteristics of photoresistor resistance changes with light.
Difference 2: How They Work
In terms of working principles, analog multimeters and digital multimeters are also different. The internal structure of an analog multimeter has a meter head, a resistor, and a battery. The meter head generally uses a magnetoelectric DC microampere meter. Only when measuring resistance, its internal battery is used. The positive pole of the battery is connected to the black test lead, so the current flows out of the black test lead and the red test lead flows in. When measuring DC current, shunt the resistor by connecting a parallel resistor. Because the full bias current of the meter head is very small, a shunt resistor is used to expand the range. When measuring the DC voltage, a series resistance is connected to the meter head, and different ranges of conversion are achieved through different additional resistances.
The digital multimeter is composed of a function converter, an A / D converter, an LCD display (liquid crystal display), a power supply, and a function / range conversion switch. Among them, the A / D converter generally uses the ICL7106 double-integral A / D converter. . ICL7106 uses two integrations. The first integration of the input analog signal V1 is called the sampling process; the second integration of the reference voltage-VEF integration is called the comparison process. The two integration processes are counted by a binary counter, converted into digital quantities, and displayed in digital form. To measure AC voltage, current, resistance, capacitance, diode forward voltage drop, transistor amplification factor, and other power, a corresponding converter must be added to convert the measured power into a DC voltage signal.
Difference 3: Battery Polarity
Digital multimeters and analog multimeters have different battery polarities: the digital red test lead is connected to the positive pole of the battery, the black test lead is connected to the negative pole, and the pointer is the opposite. The diode measured by the digital meter exactly matches the actual polarity of the diode, while the pointer type is just the opposite.
Difference 4: How to use
In use, analog multimeters are equipped with mechanical zero adjustment knobs or adjustment screws. If the hands are not pointed at the mechanical zero (that is, the zero point of the voltage scale and the infinity of the ohm scale), you must use your finger or a screwdriver to lightly and stably Slowly turn the mechanical zero adjustment mechanism to return the hands to zero to eliminate the zero error. The digital multimeter has an automatic zero return function, which is more convenient.
In addition, many digital multimeters now add a lot of functional gears compared to analog multimeters, such as capacitance, frequency, temperature, and triode measurement gears. They also have some improvements in sensitivity, accuracy, and overload capacity. In general, digital multimeters have obvious advantages, but they cannot completely replace analog multimeters. There are different advantages in different measurement scenarios. You need to choose according to your actual measurement needs.
At last, after reading this article, there may be another one you will be interested in. It is about the application of multimeter-how to test capacitors by using a multimeter. Enjoy reading and welcome your comments!
