What is a Voltmeter? A Voltmeter is an instrument used formeasuring the electrical potentialdifference between two points in anelectrical circuit. Technically speaking, all voltmeters arebasically ammeters (device that measurescurrent in an electrical circuit), as theymeasure current rather than voltage.
What’s so special being“Digital”? General purpose analog voltmeters may have anaccuracy of a few percent of full scale, and areused with voltages from a fraction of a volt toseveral thousand volts. Digital voltmeters can bemade with high accuracy, typically better than1%. Specially calibrated test instruments havehigher accuracies, with laboratory instrumentscapable of measuring to accuracies of a fewparts per million!
CLASSIFICATION OF VOLTMETERS Voltmeters can be classified as:1) Analog Voltmeter2) Digital Voltmeter3) Electrostatic Voltmeter4) Oscilloscope Voltmeter5) Micro-Voltmeter6) Vacuum Tube Voltmeter7) Solenoid Voltmeter
DIGITAL VOLTMETER Digital Voltmeter is an electronic testingequipment that is used for measuring theelectrical potential difference between twoconductors in a circuit. Andrew Kay invented and produced thefirst digital voltmeter in 1954.
Advantages of Digital Voltmeter Digital format display aids visualconvenience. They are very accurate and have highresolution They are robust and precise than theiranalog counterparts.
Classification of DigitalVoltmeterOn the basis of analog-to-digital converter(ADC) used the digital voltmeter, digitalvoltmeters can be classified into the followingfour broad categories: Ramp-type digital electronic voltmeter. Integrating-type digital electronic voltmeter. Continuous-balance or Servo-balance digitalelectronic voltmeter. Successive-approximation digital electronicvoltmeter.
DIGITAL VOLTMETER WITH LEDDISPLAY A standard Digital Voltmeter is discussed whichcan be used in DC power supplies. The circuitemploys the ADC (Analog to Digital Converter)I.C. CL7107. This IC incorporates in a 40 pincase and the circuitry necessary to convert ananalog signal to digital and can drive a series offour seven segment LED displays directly.
FEATURESSalient Features of the DVM: Small size Easy construction Low cost Simple adjustment Easy to read from a distance Few external components
Salient Features of the IC L7101: Great accuracy. It is not affected by noise. No need for a sample and hold circuit. It has a built-in clock. It has no need for high accuracy externalcomponents.
Technical Specifications Supply Voltage (Symmetrical) : +/- 5 V Power requirements (maximum) : 200 mA Measuring range: +/- 0 to 1,999 V DC infour ranges. Accuracy: ....................... 0.1 %
Circuit diagram of the DVM
CONCLUSIONThe versatility, accuracy, precision, robustness of Digital electronicdevices cannot be matched with that of Analog devices as theformer ones are far more superior. Digital Voltmeter is a very simpleexample of a digital electronic device, science today has expandedby leaps and bounds for the better and has given us an array ofdevices based on digital electronics which otherwise would not havebeen possible if Man had held on to his analog knowledge and itslimited application. One still should not undermine the power andconcept which analog electronics has ushered upon our mindswhen we started our initial steps in the electronics/electrical world. Ithas impregnated its basic principles into our minds which shouldnever be forgotten. Science will continue its exponential progress inthis millennium with its digital facet blazing and we hope to enlightenourselves with inventions and technologies that will come across us.