Basic electronic measuring instruments: Principles and practice.

Abstract

Measurement refers to the act of comparing an unknown quantity with a known quantity (standard) to ascertain its value or worth. The technological advancement of any nation depends largely on its ability to measure, calculate and finally, estimate the unknown. So also, the success of any electrical and electronic expert can be judged by his ability to precisely and accurately measure and interpret electrical and electronic circuit performance. This may be why literatures have it that,the science of measurement isin consonance with human level of technological advancement. For instance, to cope with some of the technological challenges of his time,a German scientist,George Simon Ohm (1787 – 1854)had to build his own measuring instruments and apparatus. To measure current, for example, Ohm constructed a primitive electrical measuring instrument called ‘galvanometer’ which made practical use of a discovery that a current would cause a nearby compass needle to deflect and the greater the current, the greater the amount of deflection. In fact, galvanometers were one of the very few electrical instruments available commercially in those days, and consisted of a vertical coil of wire enclosing a horizontal, balanced, magnetized needle. But, as Ohm realized, galvanometers built by different people would not produce standard measurements. To preclude these difficulties, the instrument had to be carefully aligned so that the earth’s magnetic field would provide a restraining torque on the needle. Furthermore, the deflection of the magnetic needle was notproportional to that current. So Ohm had to make his own instruments to measure voltage and current, for which there were no units of measurement, and whose scales were not even proportional to the values being measured. In light of all these difficulties, we can only appreciate the creative imaginations of researchers such as Ohm, and be in awe at the results they were able to achieve. Today, we have a standard and internationally-accepted set of both electrical andelectronics measuring instruments that can measure values with great accuracy and precision. The technological feats in electronic measurements have made our dreams of going to the moon a reality. Certainly, the various electrical and electronics luxuries we enjoy today were only possible through advancements in the measurement science that has produced precision devices. These devices utilize the movements of electrons to measure values with overwhelming accuracy. However, one of the differences being that, the control of electronic movements is more effective in electronic instruments than in their electrical counterparts. The electronic measuring instruments are equipped with amplification, displayand storage elements such as diodes, transistors, vacuum tubes, plasmas and flip-flops devices that make them more robust and user friendly. They can detect, display and store respectively, small values of signals to be measured. The multimeter, for example, as one of the basic electronic measuring devices, incorporates semiconductors, diodes and ICs that help enhance its performance to measure electrical quantities in milliamps and so on. However, the question is: What are the electronic instrument performance limitations? Through the following discussions on practical application as well as principles of operation of electronic measuring instruments, alongside lively, interesting and relevant case studies, readers will learn how the basic electronic measuring instruments can be employed to measure or test electronic components accurately. This book will further reveal to the readers, the significance of good measurement practices using Multimeters, Logic Probes, Oscilloscopes, Signal Generators and Frequency Counters to carry out measurements with negligible errors in our various areas of electronic troubleshooting. With the invention of these basic electronic measuring instruments, we can say confidently that depending on how keen one’s wits are and observing the stated guidelines, one can perform measurement of electrical quantities with little or negligible error.