ELECTRONIC VERSUS ELECTRICAL INSTRUMENTS

Both electrical and electronic instruments measure electrical quantities like voltage and current etc. Purely electrical instruments do not have any built-in amplifying device to increase the amplitude of the quantity being measured. The common dc voltmeter based on moving-coil meter movement is clearly an electrical instrument. The electronic instruments always include in their make-up some active electron device such as vacuum tube, semiconductor diode or an integrated circuit etc.

The main distinguishing factor between the two types of instruments is the presence of an electron device in the electronic instruments. Of course, movement of electrons is common to both types, their main difference being that control of electron movement is more effective in electronic instruments than in electrical instruments. Although electronic instruments are usually more expensive than their electrical counterparts, they offer following advantages for measurements purposes:

1. Since electronic instruments can amplify the input signal, they possess very high sensitivity i.e. they are capable of measuring extremely small (low-amplitude) signals,

2. Because of high sensitivity, their input impedance is increased which means less loading effect when making measurements,

3. They have greater speed i.e. faster response and flexibility,

4. They can monitor remote signals.