The Cheapest Meter on Banggood

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.

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Fluke 12E+ Multimeter Hacking Hertz So Good

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.

fluke_12E_CDuring 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.

Thanks to [jacubillo] for the tip!

Hacking A Fluke Multimeter To Serve Readings Over WiFi

Your multimeter is probably your most useful instrument if you work regularly with electronics. It goes with you everywhere, and is your first port of call in most cases when you are presented with a piece of equipment. And when you think about it, it’s a pretty amazing instrument. Multimeter technology has advanced to the point at which even an inexpensive modern device has functions that would have required a hefty budget a few decades ago.

There is still one thing affordable multimeters remain unable to do: they can’t log their readings for analysis on a computer. They’re an instantaneous instrument, just as they always have been.

Lord of Hackaday [Sprite_TM] decided to hack his multimeter to serve its readings over Wi-Fi. Rather than start with a throwaway meter from the bargain bin, he did it with a Fluke. The meter he chose was a Fluke 15B+, the company’s budget offering for the Indian and Chinese markets, since he had one spare.

Opening up the 15B+, he was presented with its processor concealed under a blob of epoxy and thus unidentifiable. Armed with the knowledge that other similar Flukes contain Fortune Semiconductor parts, he investigated as many data sheets as he could find from the same company and finally identified it as an FS98O24 one-time-programmable microprocessor. Sadly this chip has no serial port, but he did find an I2C EEPROM which he correctly guessed held calibration settings. Removing this chip gave him a meter with slightly off calibration, but also gave him a serial port of sorts.

Further detective work allowed him to identify the baud rate, and supplying random commands delivered him some that returned data packets. Eventually he identified a packet containing the states of the LCD’s segments, from which he could derive its displayed value. Connecting an ESP8266 module with appropriate software left him with a Wi-Fi connected multimeter. There was a little more refinement to his hack, he created a power management board to activate the ESP when needed, and a neat hack to display its IP address on the screen.

Multimeter hacks have featured several times here at Hackaday. We’ve had another serial port hack, or how about a remote display for another Fluke on a Gameboy Advance?

Is Your Cat 6 Ethernet Cable Cat 6? Probably Not.

Though we’ve never used their cables, [Blue Jeans Cable] out of Seattle, WA sure does seem to take the black art of cable manufacture seriously. When they read the Cat 6 specification, they knew they couldn’t just keep building the cables the way they used to. So they did some research and purchased a Fluke certification tester for a measly 12,000 US dollars. While they were purchasing the device, they ran across an interesting tidbit in the fluke knowledge base. Fluke said that 80% of the consumer Cat 6 cables they tested didn’t begin to meet the Cat 6 specification.

This is the part where [Blue Jeans Cable] earns our respect; like good scientists, they set out to replicate Fluke’s results. Sure enough, 80% of the Cat 6 cables they tested from big box stores etc. failed the specification. More surprising, many of them didn’t even pass the Cat 5e specification. [Blue Jeans Cable] asserts that this is possible because the Ethernet cable specification is policed via the honor system, allowing manufacturers to be fairly brazen about what they label as Cat 6.

Exploding Multimeter Battle Royale

If you check out eBay, Amazon, or the other kinda-shady online retailers out there, you’ll quickly find you can buy a CAT III (600V) rated multimeter for under $50. If you think about it, this is incredible. There’s a lot of engineering that needs to go into a meter that is able to measure junction boxes, and factories in China are pushing these things out for an amazing price.

Over on the EEVBlog, these meters are being pushed to the limits. Last month, [joeqsmith] started a thread testing the theory that these cheap meters can handle extremely high voltages. A proper CAT III test requires a surge of electrons with a 6kV peak and a 2 ohm source. With a bunch of caps, bailing wire, JB Weld and zip ties, anyone can test if these meters are rated at what they say they are. Get a few people on the EEVBlog sending [joeqsmith] some cheapo meters, and you can have some real fun figuring out how these meters stack up.

The real experiments began with [joe smith]’s low energy surge generator, a beast of a machine that can be measured with an even beastlier high voltage scope probe. This is a machine that will send a voltage spike through anything to short out traces on poorly designed multimeters.

How did the cheapo meters fare? Not well, for the most part. There was, however, one exception: the Fluke 101. This is Fluke’s My First Multimeter, stuffed into a pocketable package. This meter is able to survive 12kV pulses when all but two of the other brands of meters would fail at 3kV.

What’s the secret to Fluke’s success? You only need to look at what the Fluke 101 can’t do. Fluke’s budget meter doesn’t measure current. If you ever look inside a meter, you’ll usually find two fuses, one for measuring Amps and the other for all the other functions on the scope. There’s quite a bit of engineering that goes into the current measurement of a meter, and when it goes wrong you have a bomb on your hands. Fluke engineers rather intelligently dropped current measurement from this budget meter, allowing them to save that much on their BOM.

There’s an impressive amount of data collected by [joeqsmith] and the other contributors in this thread, but don’t use this to decide on your next budget meter; This is more of an interesting discovery of how to make a product that meets specs: just cut out what can’t be done with the given budget.

Give your Multimeter a Wireless Remote Display

Multimeters are one of the key tools in a hardware hacker’s bench. For 90% of us, the meter leads are perfect for making measurements and looking over at the results. Sometimes you need a bit more distance though, and for that, [Ken Kaarvik] has created the Multimeter remote display. Remote displays are pretty handy when you want to measure something several feet away from your bench. They’re also great if you need to check something in an enclosed space, like a server rack or a refrigerator. Fluke actually sells multimeters with wireless displays, such as their model 233.

The key to this project is the FS9721 LP3 chip by Fortune Semiconductor. (PDF link) The FS9721 is essentially a system on chip (SOC) for multimeters. It contains a digital to analog to digital converter, an LCD driver, and a microcontroller. It also can send data out over a 2400 baud serial link. Two of [Ken’s] multimeters, the Digitek DT-4000ZC and a Fluke 17B, both have this chip. The Digitek has a 1/8″ plug for connecting to the outside world, while the Fluke requires some simple hardware mods to enable data output.

Since this was his entry for the Trinket EDC contest,  [Ken] connected the serial output of the FS9721 to an Adafruit Pro Trinket. The Trinket formats the data and sends it to an  nRF24L01+ 2.4GHz radio module. The receiving end has an identical radio, and another Pro Trinket. [Ken] actually built two wireless displays. One is a dual-boot Game Boy advance which has a really slick background on the color display. The other receiver utilizes a 128×64 OLED. The trinket, nRF24L01+ and display all fit neatly inside an Altoids tin.

Click past the break to see both wireless remote displays in action!

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Voltset Multimeters at World Maker Faire

Many tents at World Maker Faire were divided up into booths for companies and various projects. In one of these tents, we found the Voltset booth. [Tom, Ran, and Michael] were on hand to show off their device and answer any questions. Voltset is essentially a multimeter which uses your phone as a display. It connects to an Android phone via USB or an optional Bluetooth module.

Now we’d be a bit worried about the risk of damaging our phones with a voltmeter electrically connected via USB. However, many people have an old phone or retired tablet kicking around these days, which would be perfect for the Voltset. The Bluetooth module alleviates this problem, too – though it doesn’t fix the issue of what happens to the multimeter when someone decides to call.

Voltset isn’t new; both the Voltset team and the similarly specced  Mooshimeter were also at World Maker Faire last year. In the interim, Voltset has had a very successful Kickstarter. The team is accepting pre-orders to be shipped after the Kickstarter backers are sent their rewards.

voltset-2[Tom] told us that the team is currently redesigning their hardware. The next generation prototype board with more protection can be seen in the far right of the top photo. He also mentioned that they’re shooting for 5 digits of accuracy, placing them on par with many bench scopes. We’re skeptical to say the least about 5 digits, but the team is definitely putting their all into this product. We’ll wait until the Kickstarter backers start getting their final devices to see if Voltset is everything it’s cracked up to be.