Multimeter

A multimeter or a multitester, also known as a volt/ohm meter or VOM, is an electronic measuring instrument that combines several measurement functions in one unit. A typical multimeter may include features such as the ability to measure voltage, current and resistance. There are two categories of multimeters, analog multimeters and digital multimeters.A multimeter can be a hand-held device useful for basic fault finding and field service work or a bench instrument which can measure to a very high degree of accuracy. They can be used to troubleshoot electrical problems in a wide array of industrial and household devices such as batteries, motor controls, appliances, power supplies, and wiring systems.Multimeters are available in a wide ranges of features and prices. Cheap multimeters can cost less than US$10, while the top of the line multimeters can cost more than US$5000.
History:-

Scientists originally used galvanometers to measure current. A galvanometer may be wired to measure resistance (given a known voltage source) or voltage (given a fixed resistance). While appropriate for primitive lab use, switching from one setup to another is inconvenient in the field.Multimeters were invented in the early 1920s as radio receivers and other vacuum tube electronic devices became more common. The invention of the first multimeter is attributed to Post Office engineer Donald Macadie, who became dissatisfied with having to carry many separate instruments required for the maintenance of the telecommunication circuits.Macadie took his idea to the Automatic Coil Winder and Electrical Equipment Company.The first AVO was put on sale in 1923, and although it was initially a DC-only instrument many of its features remained almost unaltered right through to the last Model 8.As modern systems become more complicated, the multimeter is becoming more complex or may be supplemented by more specialized equipment in a technician's toolkit. For example, where a general-purpose multimeter might only test for short-circuits, conductor resistance and some coarse measure of insulation quality, a modern technician may use a hand-held analyzer to test several parameters in order to validate the performance of a network cable.