Open Source Multimeter Raises The Bar For DIY Tools

December 25, 2024 by 37 Comments

Whether you only dabble in electronics as a hobby or it’s your full-time job, there are few tools as indispensable as the multimeter. In fact, we’d be willing to bet nearly everyone reading this site owns at least one of them. But as common and mindbogglingly useful as they may be, they aren’t perfect. Even the high-end models will invariably have some annoyance that only reveals itself once you become intimately acquainted with it.

Most people would just live with those quirks, especially when dealing with a cheaper model. But not [John Duffy]. Deciding nothing but perfection would do, he took every favorite feature he’d ever run into while using other multimeters and combined them into his scratch-built HydraMeter. In the process, he managed to come up with a few new ideas that push this device into a league of its own.

Some of the features of the HydraMeter will look familiar. You might even have them on your own personal meter, such as the wireless removable display module. Other features you’ll wish your meter had, such as the removable cartridge on the front of the device that lets you rapidly swap out a burned fuse. On the other side of the spectrum, there are some esoteric features that might leave you scratching your head. The ability to tell exactly how the meter is configured at a glance thanks to its exclusive use of toggle switches has a certain hacker appeal, but it’s a tricky user interface for most folks.

While the overall design of the HydraMeter may be divisive, one thing we can all agree on is that getting the project to this state took incredible determination. Over the years we’ve only seen a handful of individuals attempt to develop their own multimeters, and even then, none of them approached this level of fit and finish. The fact that [John] has turned all that effort over to the community by releasing his design under the CERN license is truly admirable.

[John] brought the HydraMeter out to Pasadena back in November for Supercon, and it got quite a reaction. And if you don’t like the user interface, it’s not hard to imagine how you could change it. This project has unquestionably pushed the state of the art for open source multimeters forward, and we’re eager to see where it goes from here.

Continue reading “Open Source Multimeter Raises The Bar For DIY Tools” →

Multimeter Gets Socket Upgrade To Use Nicer Probes

December 20, 2024 by 11 Comments

[Piffpaffpoltrie] had a problem. They found the InLine VA40R to be a perfectly usable multimeter, except for a couple of flaws. Most glaring among these were the tiny sockets for the test probes. These proved incompatible with the probes they preferred to use, so naturally, something had to be done. 

The desire was to see the multimeter work with [Piffpaffpoltrie]’s connector of choice: the 4 mm Multi Contact banana plug from Stäubli. Swiss-made, gold-plated, and highly reliable, nothing else would do. The original sockets on the multimeter were simply too small to properly accept these, so to make them work, they were machined down, drilled, tapped, and then fitted with a short M3 screw which was then soldered in place. This short length of thread then allowed the new sockets to bolt right into the PCB in place of the original sockets.

Ultimately, many would just buy a new multimeter. This hack is a fiddly and time-consuming one, but it’s kind of neat to see someone go to such lengths to customize their tools to their own satisfaction.

We don’t see a lot of multimeter hacks, because these tools usually get all the necessary features from the manufacturer. Still, the handful we’ve featured have proven most interesting. If you’re tinkering away at customizing your own test gear, don’t hesitate to drop us a line!

It’s A Soldering Iron! It’s A Multimeter! Relax! It’s Both!

November 15, 2024 by 22 Comments

Imagine this. A young person comes to you wanting to get started in the electronic hobby. They ask what five things should they buy to get started. Make your list. We’ll wait. We bet we can guess at least two of your items: a multimeter, and a soldering iron. [LearnElectroncsRepair] recently showed us a review of the Zotek Zoyi ZT-N2 which is a soldering iron and a multimeter in one unit. You can watch the video review below.

Honestly, when we heard about this, we didn’t think much of the combination. It doesn’t seem like having your probe get red hot is a feature. However, the probe tip replaces the soldering iron tip, so you are either soldering or measuring, but not both at the same time.

Continue reading “It’s A Soldering Iron! It’s A Multimeter! Relax! It’s Both!” →

Close up of a DA14 nixie multimeter

The Nixie Tube Multimeter That Almost Made A Comeback

November 1, 2024 by 3 Comments

In a world of digital monotony, the Avo DA14 digital multimeter, with its vintage nixie tube charm, is a refreshing gem. Recently refurbished by [Thomas Scherrer], this multimeter video review is a blend of nostalgia and tech savvy. The DA14 not only has style, but substance — delivering resistance, current, and voltage measurements that make you wonder why more multimeters didn’t stick with this stylish glow.

As [Thomas] starts by powering up the DA14, we were instantly captivated as the Nixie tubes illuminate in their retro orange. With each twist of the dial, he demonstrates just how intuitive the multimeter is to operate, walking us viewers through each function while giving some extra love to its calibration process—a neat front-panel potentiometer that requires just a touch of finesse to get perfect readings.

But, as with all good tinkering tales, things go downhill when issues with analog inputs and the display pop up. A teardown reveals a beautifully complex inner assembly of transformers, rectifiers, and circuit boards, giving the DA14 its impressive yet fragile structure. When the critical defective display chip is found, hopes for a full repair dim. His story ends without a revival, but if you want to see a similar attempt that did get resurrected – albeit without those nixie digits – take a look at this LCD transplant we covered previously.

Continue reading “The Nixie Tube Multimeter That Almost Made A Comeback” →

Insides of a multimeter, improved with a custom backlight switch.

Backlight Switch For A Better Multimeter

August 26, 2024 by 28 Comments

Frustrated by his Aldi multimeter’s backlight turning off after just 15 seconds, [Steg Steg] took matters into his own hands. His solution? He added a manual toggle switch to control the backlight, allowing it to stay on as long as needed. He began by disassembling the multimeter—removing the outer bumper and a few screws—to access the backlight, labeled “BL.” He identified the voltage regulator outputting 2.8 V, desoldered the red wire, and extended it to install the switch.

On his first try, he successfully drilled a spot for the SPST switch. To fit the switch into the multimeter’s rubber bumper, he used a circular punch, although his second hole wasn’t as clean as the first. Despite this minor setback, the modification worked perfectly, giving him complete control over his multimeter’s backlight without the original 15-second timeout.

Continue reading “Backlight Switch For A Better Multimeter” →

Multiply Your Multimeter With Relays And USB

April 2, 2024 by 10 Comments

Multimeters are a bit like potato chips: you can’t have just one. But they’re a lot more expensive than potato chips, especially the good ones, and while it’s tempting to just go get another one when you need to make multiple measurements, sometimes it’s not practical. That’s why something like this 2×4 relay-based multiplexer might be a handy addition to your bench

In this age of electronics plenty, you’d think that a simple USB relay board would be easy enough to lay hands on. But [Petteri Aimonen] had enough trouble finding a decent one that it became easier to just roll one up from scratch. His goal was to switch both the positive and negative test leads from up to four instruments to a common set of outputs, and to have two independent switching banks, for those times when four-lead measurements are needed. The choice of relay was important; [Petteri] settled on a Panasonic DPDT signal relay with low wetting current contacts and a low-current coil. The coils are driven by a TBD62783A 8-channel driver chip, while an STM32 takes care of USB duties.

The mechanical design of this multiplexer is just as slick as the electrical. [Petteri] designed the PCB to act as the cover for a standard Hammond project box, so all the traces and SMD components are mounted on the back. That just leaves the forest of banana-plug binding posts on the front, along with a couple of pushbuttons for manual input switching and nicely silkscreened labels. The multiplexer is controlled over USB using the SCPI protocol, which happily includes an instrument class for signal switchers.

We think the fit and finish on this one is fantastic, as is usual with one of [Petteri]’s builds. You’ll probably recall his calibrated current reference or his snazzy differential probe.

Fixing A Malfunctioning Keithley Model 179 Digital Multimeter

February 2, 2024 by 7 Comments

Inspired by electronics repair videos on YouTube, [Steven Leibson] recently found himself hunting down something to fix on eBay. This ‘something’ ended up being a  certified classic: a Keithley Model 179 digital multimeter from 1978. Listed as non-functional, the unit arrived at his door for less than $50. There weren’t any exciting pops or smoke when he powered it on, but the display seemed to be showing nothing but random nonsense.

The Keithley Model 179 multimeter has a convenient calibration sequence printed on its electrostatic shield cover and a deadly exposed ac line fuse in the upper left part of the photo. (Image credit: Steven Leibson)
The meter has a convenient calibration sequence printed on its electrostatic shield cover and a deadly exposed AC line fuse in the upper left part of the photo.

Ultimately reviving this little piece of history was quite simple, with the main issue turning out to be a dodgy inter-board connector between the main and display boards. After admiring an old repair attempt made on the component, he removed both the male and female connectors, replacing them with new ones.

This uncovered issues with the PCB, as the FR4 material and the traces on it had begun to delaminate, probably due to the old adhesive giving up due to age. With pretty low trace density this wasn’t anything that a bit of care couldn’t work around, fortunately.

Before finding this dodgy connector, [Steven] first tried to clean the front mechanical connectors, which took multiple sessions. This was followed up by oiling the mechanism. With the connector fixed and some cleaning, the meter’s display now read correctly. It still has some issues with starting up though, which [Steven] reckons are due to the old capacitors in the device.

Presumably some recapping will round off this fun device revival experience, but for the time being a Keithley Model 179 has been saved from e-waste, to inspire generations to come.