Why You Shouldn’t Quite Forget The Moving Coil Multimeter

November 8, 2017 by Jenny List 80 Comments

Did any of you have an AWS multimeter? Was it the best? Radio-electronics magazine, August 1981. — Did any of you have an AWS multimeter? Was it the best? Radio-Electronics magazine, August 1981.

If you were to ask a random Hackaday reader what their most fundamental piece of electronic test equipment was, it’s likely that they would respond with “multimeter”. If you asked them to produce it, out would come a familiar item, a handheld brick with a 7-segment LCD at the top, a chunky rotary selector switch, and a pair of test probes. They can be had with varying quality and features for anything from a few dollars to a few hundred dollars, though they will nearly all share the same basic set of capabilities. Voltage in both AC and DC, DC current, resistance from ohms to mega ohms, and maybe a continuity tester. More expensive models have more features, may be autoranging, and will certainly have better electrical safety than the cheaper ones, but by and large they are a pretty standard item.

If Hackaday had been around forty years ago and you’d asked the same question, you’d have had a completely different set of multimeters pulled out for your inspection. Probably still a handheld brick with the big selector switch, but instead of that LCD you’d have seen a large moving-coil meter with a selection of scales for the different ranges. It would have done substantially the same job as the digital equivalent from today, but in those intervening decades it’s a piece of equipment that’s largely gone. So today I’m going to investigate moving coil multimeters, why you see them a lot less these days than you used to, and why you should still consider having one in your armoury. Continue reading “Why You Shouldn’t Quite Forget The Moving Coil Multimeter” →

The Cheapest Meter On Banggood

July 17, 2017 by Al Williams 61 Comments

According to [pileofstuff], he didn’t really need another digital multimeter. However, when he saw a DT-832 meter on Banggood for the princely sum for $4.99 he wondered just what kind of meter you’d get for that price. You can see his conclusions in his recent video (below). He does make it clear, by the way, that he wasn’t paid for the review or given the meter. He just decided to see what $5 would buy in a meter.

Depending on your predisposition to cheap Asian electronics, you may or may not be surprised. After all, for $5 you can’t expect a top-of-the-line lab instrument. The device measures AC and DC voltage, DC amperage, ohms, transistor beta, and has a diode tester and continuity buzzer. It also has some frequency measurement capability. You can’t be too surprised it doesn’t auto range, though. To be fair, although he mentions Banggood as the source of the meter, a quick Google search shows you can get them from all the usual sources, and the price is down to $3.73 as long as you let them ship it from Canada.

Continue reading “The Cheapest Meter On Banggood” →

Hackaday Prize Entry: Safety Glasses Are Also Hands-Free Multimeter

June 4, 2017 by Bryan Cockfield 23 Comments

It seems like the multimeter is never easy to see during a project. Whether it’s troubleshooting a vehicle’s electrical system and awkwardly balancing the meter on some vacuum lines and the intake manifold, or installing a new solar panel and hoping the meter doesn’t fall on the ground while the leads are in both hands, it seems like there’s never a good way to see the meter while actually using it. Some meters have a small magnet and strap that can be used to hang them temporarily, but this will only get you so far.

[Alain Mauer]’s entry into the Hackaday Prize looks to solve this glaring problem. Using a heads-up Bluetooth display mounted to a pair of safety glasses, a multimeter can be connected to the device in order to display its information directly to its user. Based on his original idea which used a normal pair of prescription glasses as its foundation, [Alain]’s goal is to reduce safety hazards that might arise when using a multimeter in an awkward or dangerous manner that might not otherwise be possible.

The device uses an Arduino Pro Micro to connect to the multimeter and drive the display. [Alain] notes that the real challenge is with the optical system, however. Either way though, this would be a welcome addition to any lab, workspace, or electrician’s toolbox. Be sure to check out the video of it in action after the break.

Continue reading “Hackaday Prize Entry: Safety Glasses Are Also Hands-Free Multimeter” →

From 1950s Multimeter To Internet Connected Clock

March 4, 2017 by Jenny List 6 Comments

We’ve seen many clocks here over the years. Some of them are conventional, some esoteric. So it’s not often that we see something novel in the world of timekeeping.

Strictly speaking, [Giulio Pons]’s clock project isn’t new at all. He’s taken a broken multimeter from the 1950s, and with the help of an Arduino Nano and an ESP8266 module, converted it into a clock that indicates the time on the multimeter’s moving-coil meter. He’s wired the multimeter’s front panel controls to the Arduino to operate the thing, and given it a speaker to play alarm sounds. A PIR motion detector activates the clock. In the hours of darkness, a photoresistor brings up a light. Time setting is automatic via the internet. [Giulio] previously experimented with an RTC module but found the network connection made changing time settings easier.

It’s by no means the perfect timepiece. For instance, [Giulio] found that driving the meter from a PWM pin gave different readings depending on the PSU load from other parts such as the light. But the clock does work, and has breathed new life into what might otherwise have remained a piece of junk.

Those of you with long memories might remember a similar project from a few years ago that used unmodified multimeters to display time as voltage. And of course, there are always frequency counter clocks.

MacGyvering Test Lead Clips

February 23, 2017 by James Hobson 23 Comments

Okay fellow Make-Gyvers, what do you get when you cross a peripheral power cable jumper, a paperclip, springs, and some 3D-printed housings? DIY test lead clips.

Test clips are easily acquired, but where’s the fun in that? [notionSuday] started by removing the lead connectors from the jumper, soldering them to stripped lengths of paperclip, bent tabs off the connectors to act as stoppers, and slid springs over top. Four quick prints for the housings later, the paperclip assembly fit right inside, the tips bent and clipped to work as the makeshift clamp. Once slipped onto the ends of their multimeter probes, they worked like a charm.

Continue reading “MacGyvering Test Lead Clips” →

Hackaday Prize Entry: ESP Swiss Knife

July 4, 2016 by Moritz Walter 5 Comments

The best equipment won’t help you if you don’t have it with you in the moment you need it. Knowledge, experience, and a thick skin may help you out there in the mud of the hardware battlegrounds, but they can’t replace a multimeter, an oscilloscope, a logic analyzer, a serial console or a WiFi access point. [Arcadia Labs] has taken on the challenge of combining most of these functions into a single device, developing the Hacker’s equivalent of a Swiss Army Knife: The ESP Swiss Knife.

Just like a Swiss Army Knife is first and foremost a knife, the EPS Swiss Knife is first and foremost an ESP8266. That means it is already a great platform for any kind of project, and [Arcadia Labs] supercharged the plain ESP-12E module by adding a couple of useful features commonly used in many projects. There’s an OLED display, four pushbuttons, a temperature sensor, and a Li-Ion cell with a charging module to power the device on the go. A universal “utility socket” breaks out the ESP8266’s leftover GPIOs and the supply voltage for attaching further peripherals.

With the hardware up and running, [Arcadia Labs] went on with building a couple of applications to provide the functionality that would make the device earn its name. Among them is a basic oscilloscope, a digital NTP based clock, a thermometer, a WiFi tester, a weather station and a 3D printer status monitor. More applications are planned, such as a chronometer, a timer, a DSLR intervalometer and more. A protective 3D printable enclosure is also in the works. [Arcadia Labs] has been joining the Hackaday Prize 2014 and 2015 before and we’re glad to see another great build coming into existence!

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Fluke 12E+ Multimeter Hacking Hertz So Good

June 7, 2016 by Moritz Walter 30 Comments

It kind of hurts watching somebody torturing a brand new Fluke multimeter with a soldering iron, even if it’s for the sake of science. In order to find out if his Fluke 12E+ multimeter, a feature rich device with a price point of $75 that has been bought from one of the usual sources, is actually a genuine Fluke, [AvE] did exactly that – and discovered some extra features.

During a teardown of the multimeter, which involved comparing the melting point of the meter’s rubber case with other Fluke meters, [Ave] did finally make the case for the authenticity of the meter. However, after [AvE] put his genuine purchase back together, the dial was misaligned, and it took another disassembly to fix the issue. Luckily, [AvE] cultivates an attentive audience, and some commenters noticed that there were some hidden button pads on the PCB. They also spotted a little “C”, which lit up on the LCD for a short moment during the misalignment issue.

The comments led to [AvE] disassembling the meter a third time to see if any hidden features could be unlocked. And yes, they can. In addition to the dial position for temperature measurement, [AvE] found that one of the hidden button contacts would enable frequency and duty cycle measurement. Well, that was just too easy, so [AvE] went on checking if the hidden features had received their EOL calibration by hooking the meter up to a waveform generator. Apparently, it reads the set frequency to the last digit.

The 12E+ is kind of a new species of Fluke multimeter: On the one side, it has most of the functionality you would normally expect from a “multi”-multimeter – such as measuring both AC and DC voltage, current, capacitance and resistance – and on the other side it costs less than a hundred dollars. This is made possible by the magic of international marketing, and Fluke seems to distribute this crippleware product exclusively in the Chinese market. Therefore, you can’t buy it in the US or Europe, at least not easily. A close relative of the 12E+ which should be a bit easier to obtain is the Fluke 15B+; the meter we saw earlier today when [Sprite_TM] hacked it to share measurements via WiFi. The 15B+ seems to be identical to the 12E+ in appearance and features, although it’s unknown if the two are hackable in the same ways.

https://www.youtube.com/watch?v=FUmbsBYVTQ0

Thanks to [jacubillo] for the tip!