The Evolution of Multimeters: From Analog to Digital
Measuring electricity and voltage might sound quite simple, but it is an absolute necessity for taking on any project involving electronics and power supply. Our go-to apparatus in such cases is always a multimeter, which is a must-have item in any electrician’s toolbox. But how did the use of modern multimeters come into prominence? In today’s article, we will discuss the evolution of multimeters and their transition into state-of-the-art digital machines from analog devices.
WHAT ARE MULTIMETERS?
A multimeter is an electronic device that is capable of performing different types of electrical and electronic measurement tasks. It’s also known as a VOM (Volt-Ohm- Milliammeter) since it can measure voltage, resistance, and current. More advanced multimeters can also work with frequency, continuity, conductance, and other relevant variables. Price of a multimeter varies based on the features they incorporate. You can buy one for as less as $10 while a laboratory-grade multi meter will cost you thousands. Structurally, a multimeter could be thought of as a combined unit of DC and AC voltmeters, ammeter and an ohmmeter. In terms of application, multimeters also serve a wide range of purposes ranging from household to industrial uses.
EVOLUTION OF MULTIMETERS
Galvanometers heavily inspired the invention of modern-day multimeters. Hans Christian Ørsted created the earliest prototype of a galvanometer in 1820. It could only identify the existence of electric current as it produced deflections whenever current passed through its coils. Before French physicist André-Marie Ampère figured out a way to quantify the findings of a galvanometer, it was incapable of measuring any values.
A Wheatstone bridge connection with the galvanometer was used to determine voltage and resistance. A reference amount of voltage and resistance was used to find out the unknown quantity. When the unknown number matched the reference values, the bridge was balanced. This was a complicated procedure that required an extensive setup and a lot of time. On top of that, it often yielded inaccurate results.
The multimeters we use now can measure currents, resistance, and voltage. Some are capable of doing more, as we mentioned earlier, but these are the three common attributes of any multimeters. Multimeters can do what galvanometers did in the past in a compact size and with much higher accuracy. So, it could be argued that galvanometers have morphed into multimeters as time went by.
Multi meters didn’t come into the scene until after a century passed by since the invention of galvanometers. In the post-WW-1 era, radio communications were well established as a mean of communication and the use of electronics were on the rise. This led to increased necessity of correctly measuring electric variables.
Donald Macadie, a British post office engineer, realized how troublesome it was to carry around an assortment of instruments for maintenance work and attempted to build a portable device that could simultaneously measure multiple related parameters. Hence, multimeters were born.
Macadie needed to measure resistance, current, and voltage regularly for repairing and fault finding telecommunication circuits. For the sake of convenience, he felt the need for a single machine that can do all these together. Correspondingly, he built a device that could deduce all three essential values, i.e., current, voltage, and resistance. Macadie used to call this an AVO meter since it measured amperes, volts and ohms. This name was adopted by multiple British manufacturers afterward to market the item. Currently, Megger Group Limited holds the naming rights and sell its manufactured multimeters under the AVO brand.
The year Mr.Macadie passed away marks another significant milestone in the history of multimeters. Non-Linear systems created the first-ever digital multimeter. Instead of an old fashioned clock-like face and arms design, the meter boasted a digital display which showed numeric values. But it wasn’t until the 1970s that companies begin to catch on the digital multimeter or DMMs, as they are often abbreviated, trend. This is widely attributable to the fall of semiconductor price in that era. The Fluke 8020A is regarded as the first commercially successful DMM, which was made in 1977.
Just like their analog counterparts, DMMs can take on a variety of measurement challenges, but they do so with greater precision. These multimeters also come with better security features that ensure your safety while dealing with live current and voltage. They also have extra features like auto-ranging, auto-polarity, and backlights LEDs which give them a clear edge over analog multimeters.