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I'm just getting started with electronics (arduinos and friends) and I would like to get a multimeter. As far as I can tell arduinos and any other logic chips and circuits I'm gonna be using are using DC power in the 3-12V range. Multimeters with "true RMS" seem to be quite more expensive than those without and well... do I need this feature at all? Is there any other feature I should look for?

adrianton3
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  • Will you be working with AC or only stay in the 3.3-12V world? – Alexander von Wernherr Oct 05 '18 at 10:52
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    No, you don't need true RMS for getting started (but pay more than 15€). And it's worth reading what peak-values, mean and RMS is and why the readings might differ if the signal isn't a sinus – Andy Oct 05 '18 at 10:54
  • Also consider buying a logic analyzer (5 euro from China), these work in the range of about 0-5V (maybe more). – Michel Keijzers Oct 05 '18 at 10:54
  • Never had a "true RMS" meter, never needed one. Do understand the difference between "average" and "peak", and be aware that neither will accurately reflect the magnitude of an RMS voltage. But usually such accuracy is not needed. And for DC it doesn't matter at all. – Hot Licks Oct 05 '18 at 13:50

2 Answers2

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For experimenting with microcontrollers, you don't need a multimeter with true RMS. Get a cheap V, mA, and Ω meter, and save the money for a scope. You will soon be lost without at least some way of looking at voltages as a function of time.

Olin Lathrop
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    Even if you buy a cheap multimeter, please take care to select one with a reasonable burden voltage on the ranges you are planning on using. Some of the very cheap meters have burden voltages of volts on mA ranges, which render them basically useless as your system will start to break down if you have a 3 V supply and the meter is eating 1 V or more from that. Yes you can supply more, but then you disconnect the meter, forget to change the voltage back and everything goes up in smoke. – Arsenal Oct 05 '18 at 13:07
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Most of the time in electronics work multimeters are used either as a DC voltmeter or a resistance/continuity meter. A bottom of the range multimeter will do both jobs more than well enough for beginner.

On the relatively rare occasions that you want to measure current it often works out more conviniant to put in your own shunt resistor and use the voltage range on your meter. That way you don't have fuses adding burden and it's much easier to connect and disconnect the meter while the circuit remains operational.

There are a variety of reasons to spend more money on a multimeter but I don't think any of them apply to you.

  1. Safety when working on mains power systems, sure no-name chinese meters may claim to have safety approvals but those claims are pretty worthless when they are coming from some firm you have never heard of who has no legal presense in a country where the courts care about safety regulations.
  2. High precision/accuracy, a cheap multimeter only gives you a few digits, most of the time that is enough but sometimes the extra digits have value.
  3. Specific features for specific tasks, true RMS for more accurately measuring AC power systems that may have distorted waveforms, current clamps for measuring large AC currents, data logging for long term experiments etc.
Peter Green
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