The basic difference between Analog & Digital Instrument is given below.
|S.No.||Aspects||Analog Instrument||Digital Instrument|
|1.||Information form||As the position of pointer on a dial/scale||As a number|
|2.||Possibility of human error||Exists||Does not exist|
|3.||Best possible accuracy||0.25%||+0.005% or greater|
|4.||Resolution||one in several hundreds||one part in several hundred thousand|
|5.||Presence of moving parts||moving part involved||No moving part|
|6.||Construction||simple, direct reading type, can perform in unfavourable conditions||involves electronics, proper environmental conditions are required|
|7.||Rate of change of parameter||By seeing needle movement||No knowledge of change|
|8.||Time required to observe reading||If exact reading is required operator takes more time to guess the approximate tenths of small division||Very fast|
|9.||Auxiliary power requirement||No requirement of auxiliary power.||Require auxiliary source of power|
|10.||Mobility||Can be portable||Staionary|
|11.||Examples||speedometer of an automobile, fuel gauge, voltmeter, ammeter, thermometer, etc.||Digital ammeters, voltmeters, etc.|
Advantages of Digital Instruments over Analog Instruments
- The output of these instruments in the BCD format and hence it can be directly restored to a secondary storage device or processed by a computer.
- These instruments have a high impedance, this input resistance is typically up to 10 MΩ and their input capacitance is typically 40pF.
- The high input impedance results in an instrument which almost never loads the circuit in which it has been introduced.
- Due to the complete absence of the moving mechanical parts, these instruments have a zero operational power consumption.
- Digital instruments high resolution and the digital voltmeter can be designed to measure voltage as is called as 1μV on its 1V range or 1mV on its 1000V range.
- Digital instruments have a high accuracy due to the above characteristics, as high as ±0.005% of the reading.
- Digital instruments are both overanged of automatically ranged.
- These instruments are calibrated internally with the help of an internal standard stabilized source.
- Digital voltmeters cab be designed to measure voltages ranging from 1V to 1000V.