Analog Multimeters
A multimeter may be implemented with a galvanometer meter movement, or less often with a bargraph or simulated pointer such as an LCD or vacuum fluorescent display. Analog multimeters are common; a quality analog instrument will cost about the same as a DMM. Analog multimeters have the precision and reading accuracy limitations described above, and so are not built to provide the same accuracy as digital instruments.
Analog meters are able to display a changing reading in real time, whereas digital meters present such data in a manner that's either hard to follow or more often incomprehensible. Also an intelligible digital display can follow changes far more slowly than an analog movement, so often fails to show what's going on clearly. Some digital multimeters include a fast-responding bargraph display for this purpose, though the resolution of these is usually low.
Analog meters are also useful in situations where it is necessary to pay attention to something other than the meter, and the swing of the pointer can be noticed without looking directly at it. This can happen when accessing awkward locations, or when working on cramped live circuitry.
Analog meter movements are inherently more fragile physically and electrically than digital meters. Many analog meters have been instantly broken by connecting to the wrong point in a circuit, or while on the wrong range, or by dropping onto the floor.
The ARRL handbook also says that analog multimeters, with no electronic circuitry, are less susceptible to radio frequency interference.
The meter movement in a moving pointer analog multimeter is practically always a moving-coil galvanometer of the d'Arsonval type, using either jeweled pivots or taut bands to support the moving coil. In a basic analog multimeter the current to deflect the coil and pointer is drawn from the circuit being measured; it is usually an advantage to minimize the current drawn from the circuit. The sensitivity of an analog multimeter is given in units of ohms per volt. For example, a very low cost multimeter with a sensitivity of 1000 ohms per volt would draw 1 milliampere from a circuit at full scale deflection. More expensive, (and mechanically more delicate) multimeters typically have sensitivities of 20,000 ohms per volt and sometimes higher, with a 50,000 ohms per volt meter (drawing 20 microamperes at full scale) being about the upper limit for a portable, general purpose, non-amplified analog multimeter.
To avoid the loading of the measured circuit by the current drawn by the meter movement, some analog multimeters use an amplifier inserted between the measured circuit and the meter movement. While this increased the expense and complexity of the meter, by use of vacuum tubes or field effect transistors the input resistance can be made very high and independent of the current required to operate the meter movement coil. Such amplified multimeters are called VTVMs (vacuum tube voltmeters), TVMs (transistor volt meters), FET-VOMs, and similar names.
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