MERITS AND DEMERITS OF MULTIMETER

Multimeter is widely used for manufacturing and servicing of electrnoics equipment.  It has its own merits and demerits.

Merits:
It has a single meter which performs several measuring functions
it can make measurements with reasonable accuracy

Demerits:
It cannot make precise and accurate measurements due to the loading effect
Technical skill is required to handle it.

WHAT IS MULTIMETER SENSITIVITY

The resistance offered per volt of full scale deflection by the multimeter is known as multimeter sensitivity. it indicates the internal resistance of the multimeter.  If the sensitivity of a multimeter is high, it means that it has high internal resistance. when such a meter is connected in the circuit to read voltage, it will draw a very small current.  if the sensitivity is low, it would cause serious error in voltage measurement.

WHAT IS MULTIMETER

Multimeter is an electronic instrument used for measuring resistances, current and voltages. it can be used for measuring D.C aswell as A.C voltages and currents.

WHAT ARE THE APPLICATIONS OF MULTIMETER

A multimeter is used for
1)checking the circuit continuity.
2)measuring d.c. voltages across various resistors in electronic circuits.
3)measuring d.c current flowing through the cathode, plate, screen and other vacuum tube circuits
4)measuring a.c. voltages across power supply transformers
5)ascertaining whether or not open or short circuit exists in the circuit.

APPLICATIONS OF VTVM

A VTVM is used for 
1) D.C Voltage measurements:
A VTVM can accurately measure the D.C voltages in an electronic circuits.  

2)D.C Current Measurements:
VTVM does not incorporate a current scale, however current values can be found indirectly.

3)A.C voltage Measurements:
For measuring A.C voltage, a rectifier is used in conjunction with a VTVM.

4)Resistance measurements:
VTVM has ability to measure resistance upto 100 M ohms

VACUUM TUBE VOLTMETER (VTVM)

VTVM is extensively used for measuring both A.C and D.C voltages.  The Vacuum tube voltmeter has high internal resistance (>10 M ohms) and draws extremely small current. The loading effect is very small. A VTVM measures the exact voltage even across a high resistance.  A vacuum tube voltmeter consists of voltmeter and electron tubes.

WHAT IS DIAC

A Diac is a two terminal, three layer bidirectional device which can be switched from its OFF state to ON state for either polarity of applied voltage.  The diac can be constructed in either npn or pnp form.

MERITS AND DEMERITS OF VTVM (VACUUM TUBE VOLTMETER)

A VTVM is an extremely important electronic equipment and is widely used for making different measurements in electronic circuits.

Merits:
* A VTVM draws extremely small current from the measuring circuit.  therefore it gives accurate readings.

* VTVM uses triodes, the voltage to be measured is amplified.  This permits the use of less sensitive meter.

*There is little effect of temperature variations

*It has wide frequency response

Demerits:
*Accurate readings can be obtained only for sine waves.

*It cannot make current measurements directly.