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This article below is going to talk about how to buy a digital multimeter. Nowadays, DMM ( digital multimeter) prevail the electrical tester market, analog multimeter has lost its dominance.

1. Accuracy: if you are not a metrology engineer, so a standard accuracy is good enough, as most of DMMs now have the accuracy of 1% or better for DC ranges 2% or better for AC ranges. You should know that the analog multimeter usually has the accuracy of 2.5% or worse. So accuracy for Digital multitester is not the problem.

2. Input impedance: most of DMMs now have 10Mohm or higher for DC voltage ranges, 1Mohm or higher for AC voltage ranges. That is quite good, so this parameter is not a problem either.

3. Measurement features: most of DMMs can measure: AC voltage, DC voltage, DC current, AC current, resistance, continuity, diode check.
You may want some more features: capacitance, frequency, temperature, humidity, pressure, transistor hFE measurement

4. Automatic switching ranges: cheap Digital multimeters have no this feature, while it is very useful and safe, especially, when you need to measure the unknown high value of voltage, current. On the other hand, Digital multitesters with this feature also have good enough input protection, that is the most important.

5. Measuring ranges: most Digital multimeters have good enough wide ranges: DC voltage of 100mV to 700…1000V, AC voltage of 400mV to 600…1000V, DC and AC current up to 10A, resistance from tens to 30…40Mohm.
You may want the lower ranges of DC or AC voltage ranges, so check carefully with the DMM’s manufacturer documents. In general, the DMM itself cannot have higher ranges of measurement due to unstability. If you want higher ranges, you should look for the auxiliary attachments.

6. The other features, you should take into accounts:
- fast display rate. Most cheap Digital multimeter are bad in this feature: they response to the change of measured value very slow, and sometimes you cannot be more patient to wait the display changes.
- big digit.
- with backlight.
- “Hold” function, to freeze the display.
- Auxiliary resistor divider for measuring the high voltage.
- Auxiliary clamp for measuring the high current.
- Output open-circuit voltage at the diode check: should be at least 3V. Be aware: some Digital multitesters use 2 x AA batteries, but this voltage is only 1.5V and practically useless. With higher voltage, you can easily test diodes, LEDs, darlington transistors, MOSFETs, …
- Ruggedness: cheap DMMs are fragile, and have no rubber holsters.

The digital multimeter, also known as a DMM, is one of the most practical and useful electrical test instruments on the market today. Digital multimeters are the best meters available that are capable of working with energized, as well as de-energized, electrical circuits. There are a variety of functions that can be helpful to both amateur and professional users such as measuring AC and DC voltages and currents, continuity, resistance, capacitance, diodes, Ohms law and power formula, frequency and duty cycle.

For safety reasons, the tips below should be considered when selecting a Digital Multimeter:

• Fused current inputs (high energy fuses)
• Overload protection on the ohms function
• Test leads that have shrouded connectors and finger guards
• Recessed input jacks
• Independent certification