Multimeters are designed to perform more than one test parameter. Amelectric offers a wide range of DMM’s, both handheld and benchtop versions.
For each application there is an appropriate model!
A basic multimeter mostly provides three measurement units:
|1.||Voltage AC and DC|
|3.||Current AC and DC|
Often multimeters may include other test parameters suchs as:
|>||Temperature (ºC and ºF)|
|>||Transistor Test (Hfe)|
|>||Logic Test (logic levels "0" and "1")|
You need to review the complete test parameters for the multimeter you are considering. The selection chart provides a quick reference for this information.
Digital or Analog?
You will notice that there are many digital multimeters on the market from which to make a selection. Digital seems to be the logical choice. However when the accuracy is not of major importance, but to be able to see changes in the displayed value is, an analog display is indispensable. Fortunately a lot of DMM’s have also a so called “bargraph”. This is an analog display based upon a row of short bars. The more bars, the higher the accuracy.
Accuracy and Resolution!
If your accuracy requirements are critical for design or service, you need a high basic accuracy, high resolution meter. If your measurements are general purpose in nature, suchs as just checking voltages or continuity of a wire, an average meter (0,5% DCV) would fit your needs. No one but you will know the accuracy required for your measurements.
What is True RMS?
With the amount of non sinusoidal power on AC power lines caused by uneven loads (motor controllers, personal computers, fax machines, printers, etc) you need a True RMS meter to make accurate measurements of AC voltage or current. Some meters also include selectable AC or AC+DC True RMS measurements which provide the most accurate measurements. Cheap DMM's only measure True RMS AC! This can lead to large errors!
Also concider the required bandwidth! Generally this is limited to 50-100kHz for the higher cost DMM’s. Low cost instruments will have a (much) lower bandwidth and give you less accuracy!