Bar-graph meters:

A simple and cheap kind of meter can be made by using a string of light-emitting diodes  or a liquid-crystal display along with a digital scale, to indicate approximate levels of current, voltage or power. This type of meter has no moving parts to break, like a digital meter. But it offers the relative reading feeling you get with an analog meter. Figure given below is an example of a bar-graph meter which is used to show the power output, in kilowatts, for the radio transmitter. It indicates 0.8 kW or 800 watts, approximately.

Figure--   A bar-graph meter. This device shows a power level of approximately 0.8kW or 800W.

The main disadvantage of the bar-graph meter is that it is not very accurate. For this reason it is not used in laboratory testing. The LED or LCD devices at times also flicker when the level is "between" 2 values given by the bars. This can be very annoying to some people.