In this day in age we generally have at our disposal a Digital Multimeter. Weather they are called DVOM (Digital Volt-Ohm Meter), DVM (Digital Volt Meter), DMM (Digital Multi Meter) or just meter; we use them to monitor parts of our circuits. Digital Multimeters are available as clamp on types, bench or handheld. All Digital Multimeters have input circuits that convert the signal into a voltage we can measure.
The advent of transistor and Integrated Circuits brought about both a need for easier, more precision equipment and the ability to manufacture such equipment. Early Digital Multimeters were bench top units & weighed pounds. They were quite expensive so the hobbyist, electrician or student was a largely ignored. Digital Multimeters took on a whole new challenge as more & more Transistorized electronic equipment invaded our life. Not just Engineers or factory techs. but field service and service centers techs. required a better, portable meter with more available functions. Since all signals could be routed through amplifiers, attenuators, filters etc. to end up as a voltage; we could now measure Temperature, frequency, pressure and many other signal types. What mass production did for the car, it did for test equipment especially Digital Multimeters. Now everyone can own a basic Digital Multimeter. Most common are 3-1/2 digit with resolution based on 1999 counts. The 1/2 digit is in the Most Significant Digit (MSD). The first 3 digits display 0-999 (0-9each) now the 4th or MSD 1 adds another 1000 counts to the conversion. So full scale is 1999 as in 1.999V, 19.99A, 199.9 ohms thats why the switch positions all start with 2.
Some meters are 3-3/4 meaning that the MSD now covers from 0-3 so the total count for the 3-3/4 Meter is 0-3999) so the display can read full scale 3,999 so the switch positions start with 4. Digital Multimeters convert signals in discrete Steps. Between steps there is a area where the converter is in-between values. This limits the meter in accuracy. More steps (Conversion Bits) better accuracy. Besides that between step problem and component tolerance; Digital Multimeter makers hedge their bets by listing a +- percentage AND the +- number associated with the Least Significant Digit (LSD). With AC waveforms we have the problem that most Digital Multimeters are Average reading and then are calibrated to show a RMS (Root-Mean-Square) value when displaying. This is Ok if reading AC line voltages or Oscillators producing Sine Waves. The Accuracy of a non True RMS reading Digital Multimeter can be called into question when dealing with waveforms that are not a Sine. The reading is limited to its closeness to a Sine Wave. A 5V Square wave will not display the same value as a 5V Sine wave. Bench & handheld Digital Multimeters that are listed as True RMS meters will now compute these alternate values and display them or contain circuits to measure non-sinusoidal signals. Now we have available multi ranging, Clamp on, True RMS, and Digital Multimeters with computer interface for logging.
Digital Multimeters, Digital Volt Meters, DVM, Digital Multi MetersWe offer Digital Multimeters for your bench, as well as in your tool pouch. Our line of Digital Multimeters range from inexpensive to highly sophisticated.Digital Multimeters, Digital Multi Meter, Digital Volt Meter, voltmeter