A multimeter is the first piece of test equipment most makers ever buy. Of course, many makers keep upgrading the capability or quality of their meter as their experience and knowledge increase, or their needs change. The price point of this multimeter sets it in the ‘not your first multimeter’ range, but it is definitely one for the serious maker. When most people buy a multimeter, specifications and measurement modes are the top priority, so we’ll start there.
The MM66E has a 3.75-digit, 6000-count display. 3.75 digits means that, while there are four numerals on the display, the left-most only counts from 0 to 5. The other three are full-range 0 to 9 digits. That is a trend on many current multimeters, with 4000 or 6000 counts being common. This is reflected in the specifications table, as the count defines the range steps in most cases.
Specifications are no longer enough to set a multimeter apart. Even cheap multimeters have some pretty good specifications, although whether or not they live up to their claims is sometimes questionable. The MM66E, however, has some party tricks that are a bit more than just show. Well, some of them are show, but in useful ways.
The display screen of the MM66E is an LED-lit reverse LCD. While LED backlit screens are almost standard now, with the old cold-cathode fluorescent tech long gone, reverse LCDs are a bit less common. It means that the LCD is the mask, with the data displayed as gaps in the LCD rather than as segments of it. This results in a screen with a very different contrast and response in the brain than the traditional LCD with black letters and numbers on a green-grey background. The glowing white data on a black background is far easier to read at a glance, especially where strong ambient or incidental light is concerned. While the screen is quite glossy, this doesn’t seem to impede the screen’s readability, even under the multiple LED strips lighting our workshop bench.
It is worth noting that because the LCD is electronically scanned to refresh, and the photos were taken on a phone camera which also scans, the photo does not do the display any justice. In reality, the display is evenly lit and is all brighter than even the brightest section of the photo. However, if you want it brighter still, there is a backlight function which you can engage by holding the ‘Hold’ button (for data display hold) down for three seconds.
At first glance, we thought this was a silly novelty, until we thought about it. The sockets for the probes on the MM66E have a clear plastic ring moulded into the case structure, with green LED lighting in each. However, they only illuminate when they are relevant to the mode selected.
For example, when the mode selection dial is on ‘Voltage’, the ‘COM’ and multi-use (everything except current) sockets illuminate. When the different current modes are selected, the relevant socket illuminates, but not the others. This is far more helpful than we first realised.
Many makers have destroyed a fuse or two by testing with the probes left in the wrong sockets from a previous measurement. However, this is a best-case scenario, and meter damage can be the result. It’s easy to be a little absent when concentrating on the measuring task itself and keeping fingers clear of contact and probe tips in the right place. At a glance, the illuminated sockets add a quick visual that things are not right - if there is light in one socket and a probe in another, the probe is in the right place.
NON-CONTACT AND LIVE WIRE
Non-contact sensing is not new on multimeters, but on the MM66E, it actually works. We have several meters of different brands around the DIYODE workshop and the office in general, and those that have non-contact lights are often blinking randomly because the non-contact circuit is too sensitive.
On the MM66E, there is a specific mode for non-contact voltage (NCV) detection, and the circuit is sensitive enough to reasonably detect mains wires behind walls, but not so much that it gives indications while just sitting on the workbench surrounded by electromagnetic interference, radio signals, and power spikes. Further, there is a beep sound accompanying the display.
The faster the beeps and the more lines on the display, the stronger the detection is. In addition, there is a red LED bar graph visible from the face of the meter, and from the torch window in the top if you are in a situation where you were pointing the meter so that the face is less visible. The sensitive area for the NCV detector is the top end where the torch window is.
In addition to that, the secondary function of this mode is a ‘live wire’ tester. This is a novel feature and it functions well, but we don’t like it. The mode involves connecting only one probe, and using it to find which pin in a power socket or other mains situation is the live wire, as distinct from the neutral or the earth.
Not only is it illegal in Australia to work on mains unless licensed (in which case you should already know which wire is live unless you are repairing historic, suspect, or poorly done wiring), this just feels uncomfortable. By using only one probe, you are relying on the double insulation of the meter and on its high-resistance circuit for safety.
There is no path for the current back through a neutral or earth, so if there is any fault with the meter (such as water damage or impact damage exposing the inner parts) and anything is wrong with the circuit, the current path is from the probe, through you, to ground. While we know this is unlikely, it’s still a very uncomfortable thought. It’s even more uncomfortable if it happens.
The MM66E is powered by an internal lithium battery, and has a wireless charging feature. The documentation calls this “Qi wireless charging”, but whether it is genuinely Qi-controlled or not, we don’t know. The unit comes with a charger plate that is USB-powered, and sits nested on the back of the unit under the desk stand. It has a notch for alignment so that the radiant area of the charger and the sensitive area of the receiver line up. We have no Qi chargers in the office, as the EMI is an issue in an already EMI-cluttered environment and we have many many USB sources and cables anyway, so we have been unable to test whether or not the system charges off a generic mobile device Qi charger.
However, this system does offer one big advantage even if you do have to use the included charger plate. While USB-C is more rugged than previous USB iterations, it is far from perfect. Many rechargeable multimeters available still use USB Micro-B. Anyone who forgets that the meter is still plugged in when grabbing it from the shelf or from the other end of the bench without looking closely is liable to break the USB plug off in the charging socket. That isn’t an issue with the wireless charging system. The charger plate falls out of place far more easily than any USB cable.
Charging is indicated by a four-LED bar graph on the front panel. The charger is retained by tabs at the top and a weak magnet at the bottom. However, the charger stays in place best when the unit is face-down with the charger plate on the back, and easily falls out when the unit is upright on its desk stand. This further implies that the unit is intended for charging with a mobile device wireless charger, but the manual makes no confirmation. We’ll work on verifying this, and hopefully, Altronics’ website will be able to reflect one way or another by the time you are reading this.
MINOR BUT USEFUL FEATURES
A less-defining but still useful feature of the MM66E is the torch. Pressing and holding the ‘Select’ button enables a high-brightness white LED behind the clear non-contact voltage sensor panel. There is even a lens built into this panel, which focuses the light into something of a beam. The light is not the brightness many have come to expect from even small LED torches, but consider the battery size and heat capacity of the multimeter platform. The light is bright enough to see around a shadowy electrical cabinet or computer case and read labels and wire colours.
On the subject of the ‘Select’ button, many of the secondary features such as frequency or temperature are selected by this button depending on where the mode dial is set. Helpfully, and unlike many other meters, all of the functions that require this button to be pressed, are printed in blue, the same colour as the button. This is very helpful when trying to figure out whether you need to push the range button, as on some meters, or the select button.
ACCESSORIES AND REGULAR FEATURES
Few multimeters today are manual ranging, and the MM66E is no exception. There is a dedicated ‘Range’ button if you want to manually set the range, as opposed to the ‘mode’ button on some meters which sets manual range and secondary features in one button. However, the mode dial must be used to select between volts and millivolts, which is uncommon. We hope this means increased accuracy and sensitivity in the millivolt range.
Data hold and relative measurement are available. Relative measurement is a mode where a value can be set in storage, then the display will show the amount over or under this stored value. AC measurements are shown in true RMS, not average. Frequency is available on all of the voltage and current ranges, which is also unusual. It is a secondary function in each case, so pressing the ‘Select’ button changes the display mode.
Besides that, the meter comes with the standard soft plastic outer moulded holster and hard plastic body shell; good quality probes of a reasonable length with what is stated to be, and appears to be, silicone sheathing; a basic thermocouple with banana plug ends, and of course the dedicated charging plate with a small USB Micro-B cable. There is a printed manual, and a digital download is available for those who prefer it.
The MM66E multimeter from Altronics is a very good meter for its price, and it has some features that we haven’t encountered before or don’t see often. It is solidly built and rugged, overall handy with a very visible and easy to read display, in a package that still sits well in the hand of average size.
Whether or not it is for you depends on what you want out of a meter, and how much you have to spend. However, we feel that the price scales well against other meters with a similar list of features and specifications. We like it enough that we asked our friends at Altronics to send two more, so that we can give all three away as prizes. ■
|Maximum Display Count
|1 x 14500
|600mV, 6V, 60V, 600vV 1000V
|600mV, 6V, 60V, 600V, 1000V
|600µA, 6000µA, 60mA, 600mA, 10A
|600µA, 6000µA, 60mA, 600mA, 10A
|600Ω, 6000Ω, 60kΩ, 600kΩ, 6MΩ
|2V test, 50Ω max
|0.5V to 0.8V, open circuit >2V
|-20 to 0, 0 to 400, 400 to 1000
|Varies with range
|-4 to 32, 32 to 752, 752 to 1832
|Varies with range
|10Hz, 100Hz, 1kHz, 10kHz, 100kHz, 1MHz, 10MHz
|6nF, 60nF, 600nF, 6µF, 60µF, 600µF, 6mF, 60mF
|4% to 5%
- Available from Altronics Q1073A A$99