How to Buy a Multimeter

Are you planning to buy a multimeter and need help? Here are some timps

How to Buy a Multimeter covers what you need to know to select a meter for DIY electronics. It focuses on the needs for audio electronics, but it’s purposely kept general in nature.

Handheld Digital Multimeters are mainly used to measure resistance, as well as DC/AC voltage and current. Common multimeters can be divided into two types, desktop and handheld digital multimeters depending on their sizes. A handheld digital multimeter is basically composed of Analogue Front End (AFE), MCU, Human-machine interface and Power supply. The design of handheld multimeters should focus on the features of low power, high performance and compact size.

Look for these features when buying a multimeter article tells that multimeters can be handy for troubleshooting PC power problems (I would say it is a must have). But the range of features and prices can be confusing when you’re shopping for one. Before you waste time and money, find out which features are essential and which are merely nice to have.

EEVblog #75 – Digital Multimeter Buying Guide for Beginners

EEVblog #91 – $50 Multimeter Shootout – Extech EX330, Amprobe AM220, Elenco, Vichy VC99, GS Pro-50

$50 Multimeter Comparison and Teardown article tells about a very nice video series on multimeters. Here is maybe the most interesting video from it:

$50 Multimeter Shootout – Part 7 – 15 DMMs Compared! – Teardowns – #0074

 

3 Comments

  1. Washington Plumber says:

    After reading this post I thought it was the best article I ever read I appreciate you for this post and want to say keep sharing it with me.

    Reply
  2. Tomi Engdahl says:

    Why You Shouldn’t Quite Forget The Moving Coil Multimeter
    https://hackaday.com/2017/11/08/why-you-shouldnt-quite-forget-the-moving-coil-multimeter/

    There was a period through the 1980s into the 1990s, when the transition between moving coil and digital was in full swing. Everyone wanted a digital meter because they were cool. They had both precision and accuracy, instead of saying “That’s about 5 volts”, you now knew it was exactly 4.98 volts.

    So we can make fun of 1980s fashions, both sartorially and in test equipment, but what’s the real benefit of a digital meter? It lies in the internal resistance. When you hook a moving-coil meter into a circuit, you are doing work, drawing energy from the circuit being measured to move that pointer. Imagine the meter itself in a hypothetical inexpensive moving-coil multimeter, that has a full scale deflection of about half a milliamp. To take a reading at full scale the meter must then draw 0.5 mA from the circuit being measured. So to give a full scale deflection of 10 V for example the meter must have a resistor in series with it of value 10 KΩ, and measuring a voltage thus involves placing what is in effect a 10 KΩ resistor into the circuit in question. Most decent moving coil multimeters had meters with much lower full scale deflections that required greater series resistances, but the principle was the same. A moving coil multimeter loads the circuit it was testing, altering its characteristics.

    The problem of meter resistance was one for which there were solutions in the age before digital meters. Many decades ago you could buy a valve (tube) voltmeter

    So why should you have a moving-coil meter on your bench, if digital meters are so good? Aside from looking a bit retro and never having to worry about the batteries running out, that is. The answer lies in being able to measure voltages that change. If you have ever worked with radio or with analogue circuits that require adjustment you will know something of this, tuning for a peak or a trough is extremely difficult when you have no view of the trend. A typical use for a moving coil meter here is to set up an RF amplifier by tuning a tank coil, there will always be a peak in the current drawn by the amplifier as the coil reaches resonance.

    The moving coil meter of choice here for the last 30 years or so has been a venerable Avo 8. This is the classic mid-twentieth-century multimeter, a large and heavy Bakelite unit with an extremely high quality meter lurking within it.

    MF47 can be had from the usual Chinese suppliers for about £15, or $20. It’s not the most compact of multimeters, having a front panel slightly larger than and being about three times as thick as a DVD case.

    Comments:

    A vintage needle meter – hipster engineer.

    Brain-fart, but we use to have both. The analog was pretty cheap, even back in the day.

    There’s things that you should probably check out with other types of equipment that you can at least “see happening” on a moving coil meter, that are very hard to read on a digital. Examples might be voltage ripple (needle twitching), back EMF of a coil, the difference between a capacitor that’s failed open circuit and one that’s still capacitating away (Whether the value has drifted or not.)

    Reply
  3. Tomi Engdahl says:

    The Worst Piece Of Test Equipment You’ve Got To Try Hacking
    https://hackaday.com/2017/11/28/the-worst-piece-of-test-equipment-youve-got-to-try-hacking/

    I have a fascination with the various online vendors of electronics and other manufactured goods from China. Here are listed the latest wonders from Shenzhen or wherever, which you can have for a surprisingly reasonable price, with the mild inconvenience of a three week wait for the postage.

    So when I was shopping for a multimeter recently I took a quick look to see what the cheapest model from that particular supplier was. For somewhere around £2.50 or just over $3, I could have a little pocket analogue multimeter, the kind of “My first multimeter” that one might have found in the 1980s. They weren’t too bad, I thought, and ordered one for less than a pint of beer in a British pub.

    What arrived was promising enough, in a plastic blister pack, the Sunma YX1000A.

    Opening up the meter for a teardown, and I found a single printed circuit board, with as expected the selector switch formed by PCB pads. With the exception of a through-hole rectifier diode and trimmer used as the zero adjustment for the resistance ranges, all components were surface-mount.

    There was no plating on the pads, save for the HASL or similar PCB tinning. Those pocket meters back in the day would usually fail because of oxidation of these contacts, no doubt this one would eventually succumb to the same fate.

    The Sunma YX100A then: A case with a chip in it, a wildly oscillating meter mechanism that evidently has no damping, a stripe of grey paint for a parallax mirror, and a consistent 20% low reading. Even with a slightly tongue in cheek review, it’s fair to say that I have had better multimeters than the Sunma. In fact it’s fair to say that every multimeter I have ever used has been better than the Sunma. It’s possible that to make a multimeter worse than the Sunma would be extremely difficult, but they must have done it, because as they say, this is the “Improved Modeli”. Just how bad was the previous unimproved model?

    Reply

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