Definition: The instrument which represents the measurand value in the form of the digital number is known as the digital instruments. It works on the principle of quantization. The quantization is the process of converting the continuous input signal into a countable output signal.
The construction of the digital instrument is very complex, and their cost is also very high. The digital instruments consume very less power as compared to analogue instruments. The digital multimeter, digital voltmeter, digital frequency meter, etc. are the examples of the digital instruments.
Important characteristic of Digital Instruments
The digital devices have following important features.
- The accuracy of the digital electronic instrument is very much high.
- The digital instrument consists sensitive elements which are easily reacted with the surrounding temperature and humidity.
- The input impedance of the digital instrument is very high because of which it can draw very less power.
- The digital instrument is less portable.
- The cost of the instrument is high.
- The instrument is free from the parallax error.
In analogue instruments, the pointer is used for indicating the measuring voltage because of which the parallax error occurs. While in digital instruments the output is display on the screen. Thus, the chances of errors are less on it.
Construction of Digital Instrument
The construction of the digital instrument is shown in the figure below.The transducer, signal modifier and the display devices are the important part of the digital instrument.
- Transducer – The transducer is used for converting the non-electrical or physical quantities (temperature, displacement etc.) into an electrical quantity like voltage, current etc. which is easily measured by the meter. The transducer is not required for the electrical input.
- Signal Modifier – It is used for modifying the input signal of very weak strength.
- Display Device – The display device is used for showing the measurand quantities in the numeric form. Mostly, LED or LCD is used as a digital display.
Advantages of Digital Instrument
- The digital instruments display the reading in the numeric form which reduces the error.
- The digital output is obtained by the instrument which acts as an input for the memorable devices like floppy, recorder, printer etc.
- The power consumption is less in the digital instruments.
Disadvantages of Digital Instruments
The following are the disadvantages of the digital electronics.
- The overloading capacity of the instrument is low.
- It is a temperature sensitive device.The digital instrument is made by the very delicate element which is easily affected by the atmospheric condition.
- The effect of noise is more on digital electronics as compared to the analogue instruments.
In spite of the above mention disadvantages, the digital instrument is very commonly used for the measurement.