Potentiometric type dvm, Electrical Engineering

Assignment Help:

Potentiometric type DVM: A potentiometric type of DVM, employs voltage comparison technique. In this DVM the unknown Voltage is compared with a reference voltage value is fixed by the setting of the calibrated potentiometer. The potentiometer setting is changed to obtain balance (i.e. null condition).When null conditions are obtained the value of the unknown voltage, is indicated by the dial setting of the potentiometer.

In potentiometric type DVMs, the balance is not obtained manually but is arrived at automatically. Thus, this DVM is in fact a self-balancing potentiometer .The potentiometric DVM is provided with a readout which displays the voltage being measured.

The block diagram of basic circuit of a potentiometric DVM is shown in.

The unknown voltage is filtered and attenuated to suitable level. This input voltage is applied to a comparator (also known as error detector). This error detector may be chopper. The reference voltage is obtained from a fixed voltage source. This L voltage is applied to a potentiometer R. The value of the feedback voltage depends upon the position of the sliding contact; the feedback voltage is also applied to the comparator.

The unknown voltage and the feedback voltages are compared in the comparator. The output voltage of the comparator is the difference of the above two voltages. The difference of voltage is called the error signal. The error signal is amplified and is fed to a potentiometer adjustment device which moves the sliding contact of the potentiometer. This magnitude by which the sliding contact moves depends upon the magnitude of the error signal. The direction of movement of slider depends upon whether the feedback voltage is larger or the input voltage is larger. The sliding contact moves such a place where the feedback voltage equals the unknown voltage. In that case, there will not be any error voltage and hence here will be no input to the device adjusting the position of the sliding contact and therefore it (sliding contact) will come to rest. The position of the potentiometer adjustment device at this point is indicated in numerical form on the digital readout device associated with it. Since the position at which no voltage appears at potentiometer adjustment device is the one where the unknown voltage equals the feedback voltage, the reading of readout device indicates the value of unknown voltage. The reference voltage source must be extremely stable and generally consists of a standard cell or a Zener diode sources.

 


Related Discussions:- Potentiometric type dvm

Lead acid battery, Describe the construction of lead acid battery

Describe the construction of lead acid battery

Determine the voltage in given circuit, Q. In the circuit shown in Figure w...

Q. In the circuit shown in Figure with an ideal op amp, find v o as a function of v a and v b .

Find the force between the wires, Q. A magnetic force exists between two ad...

Q. A magnetic force exists between two adjacent, parallel current-carryingwires. Let I1 and I2 be the currents carried by the wires, and r the separation between them.

Calculate the amplitude and the frequency of the sine wave, (a) The key el...

(a) The key elements of a protocol are the syntax, semantics and timing. Give a brief explanation of each of these key elements. (b) A file contains 4 million bytes. Compare

Explain series circuit, Series circuit Total resistance, R T = R1 + R2...

Series circuit Total resistance, R T = R1 + R2 + R3 The current I is the same in all parts of the circuit , I = I 1 = I 2 = I 3 The voltage drop at each resistor, V1,

Amplifier, Amplifier Usually, an amplifier or simply amp, is any devic...

Amplifier Usually, an amplifier or simply amp, is any device which changes, generally increases, the amplitude of a signal. The connection of the input to the output of an amp

Disadvantages - high level languages, Disadvantage - High  level  Langua...

Disadvantage - High  level  Languages a.Computational time is more as compared to  machine languages. b.Requires more  memory. c.Requires the knowledge of specific rules

Determine the transfer function c/r for the block diagram, Feedback amplifi...

Feedback amplifiers are of great importance in electronic circuits. The block diagram of a class of feedback amplifier is shown in Figure. Determine the transfer function C/R for t

Digital electronics logic family, For a given logic family, consider VOL = ...

For a given logic family, consider VOL = 0.25V and VOH = 5 V . For a given circuit, VIL = 0.96 V and VIH = 2.18 V. Find the largest positive-going and largest negative-going nois

Write Your Message!

Captcha
Free Assignment Quote

Assured A++ Grade

Get guaranteed satisfaction & time on delivery in every assignment order you paid with us! We ensure premium quality solution document along with free turntin report!

All rights reserved! Copyrights ©2019-2020 ExpertsMind IT Educational Pvt Ltd