A Current Sensing Coil That’s Open Ended

July 16, 2023 by Jenny List 9 Comments

One of the joys of writing for Hackaday comes in learning new things which even after a long engineering background haven’t yet come your way. So it is with the Rogowski coil, an AC current sensing coil which is unlike conventional current transformers in that it’s open ended — in other words not needing to be closed around the conductor it’s measuring. [Weston Braun] has an interesting introduction to the subject, as part of his open source Rogowski coil based current probe.

The project itself is an amplifier and integrator that provides a voltage output proportional to the current sensed by the coil, but the real meat is in discovering the coils themselves. They’re a many-turn coil wound on a flexible former, forming in effect a toroidal inductor with a gap in it when bent into a circle. They’re for high frequencies only though, with the one in this project having a bandwidth from 888 Hz to 25 MHz. We don’t have any immediate need to non-intrusively measure current at those frequencies, but it’s something to know that we could.

This isn’t the first time a Rogowski coil has turned up on Hackaday though, back in 2011 we saw one used to measure a steep current impulse.

A PCB with an OLED display, a screw terminal block and a Raspberry Pi Zero board

Hackaday Prize 2023: Pi Pico Measures Volts, Amps And Watts

July 16, 2023 by Robin Kearey 6 Comments

Measuring a voltage is pretty easy: just place your multimeter’s probes across the relevant pins and read the value. Probing currents is a bit trickier, since you need to open up the circuit and place your probes in series. Checking a circuit’s power consumption is the hardest, since you need to measure both voltage and current as well as multiply them at each moment in time. Fed up with having to hook up two multimeters and running a bunch of synchronized measurements, [Per-Simon Saal] built himself an automatic digital power meter.

The heart of this instrument is an INA219 chip, which can measure and digitize voltage and current simultaneously. It outputs the results through an I2C bus, which [Per-Simon] hooked up to a miniaturized version of the Raspberry Pi Pico called an RP2040-Zero. A screw terminal block is provided to connect the system to the device under test, while a 0.96″ OLED display shows the measured voltage, current and power.

The maximum voltage that can be measured is 26 V, while the current range is determined by the shunt resistor mounted on the board. The default shunt is 0.1 Ω, resulting in a 3.2 A maximum current range, but you can get pretty much any range you want by simply mounting a different resistor and changing the software configuration. In addition to displaying the instantaneous values, the power meter can also keep a log of its measurements – very useful for debugging circuits that use more energy than expected or for measuring things like the capacity of a battery.

There are lots of ways to measure electric power, but they all boil down to multiplying current and voltage in some way. The multiplication was done magnetically in the old days, but modern meters like [Per-Simon]’s of course use digital systems. Some can even plug directly into a USB port. If you want to measure mains power, transformers are an essential component for safety reasons.

Phone Thermal Cameras Get Open Source Desktop Tools

July 11, 2023 by Tom Nardi 14 Comments

Whenever phone-based thermal cameras are brought up here on Hackaday, we inevitably receive some comments about how they’re a bad investment compared to a standalone unit. Sure they might be cheaper, but what happens in a couple years when the app stops working and the manufacturer no longer feels like keeping it updated?

It’s a valid concern, and if we’re honest, we don’t like the idea of relying on some shady proprietary app just to use the camera in the first place. Which is why we’re so excited to see open source software being developed that allows you to use these (relatively) inexpensive cameras on your computer. [Les Wright] recently sent word that he’s been working on a project called PyThermalCamera which specifically targets the TOPDON TC001, which in turn is based on a project called P2Pro-Viewer developed by LeoDJ for the InfiRay P2 Pro.

Readers may recall we posted a review of the P2 Pro last month, and while the compact hardware was very impressive, the official Android software lacked a certain degree of polish. While these projects won’t help you on the mobile front in their current form, it’s good to know there’s at least a viable “Plan B” if you’re unwilling or unable to use the software provided from the manufacturer. Naturally this also opens up a lot of new possibilities for the camera, as being connected to a proper Linux box means you can do all sorts of interesting things with the video feed.

The two video feeds on the left are combined to produce the final thermal image.

Speaking of the video feed, we should say that both of these projects were born out of a reverse engineering effort by members of the EEVblog forums. They figured out early on that the InfiRay (and other similar models) were picked up as a standard USB video device by Linux, and that they provided two video streams: one being a B&W feed from the camera where the relative temperature is used as luminance, and the other containing the raw thermal data cleverly encoded into a green-tinted video. With a little poking they found an FFmpeg one liner that would combine the two streams, which provided the basis for much of the future work.

In the video below, you can see the review [Les] produced for the TOPDON TC001, which includes a demonstration of both the official Windows software and his homebrew alternative running on the Raspberry Pi. Here’s hoping these projects inspire others to join in the effort to produce flexible open source tools that not only unlock the impressive capabilities of these new thermal cameras but save us from having to install yet another smartphone application just to use a device we purchased.

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Miniware TS1C: A Cordless Soldering Iron With A Station

July 9, 2023 by Maya Posch 19 Comments

Most soldering irons in the market seem to fall into a few distinct categories. They either provide a full-blown station to which the soldering iron is wired, powered straight by mains, or an iron powered by DC power. The Miniware TS1C takes up an interesting position here in that it features both a station you put the iron into and adjust the temperature, as well as a fully cordless iron. Sounds too good to be true, perhaps, but a recent Tom’s Hardware review by [Les Pounder] seems to think it has real merit.

Behind the glossy exterior and marketing, we find a cordless soldering iron that uses a supercapacitor to power itself when it is not inserted into the station, with communication between the iron and station performed using Bluetooth. This way, you can keep an eye on both the tip temperature and the remaining charge left, which [Les] found to be sufficient for soldering about 80 smaller joints, with the marketing claiming it can solder 180 size 0805 SMD parts with one charge.

The advantage of having a station is that it is the part that is wired to a power bank or wall wart, with the temperature setting performed using a chunky dial. The station also provides a place for the iron in between soldering sessions, but in order to recharge the iron, the brass bands near the front have to be pushed into the holder for them to make contact. This also makes one-handed removal of the iron from the holder not as easy as you’d hope.

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Roll Your Own Simple Tube Tester

July 8, 2023 by Al Williams 5 Comments

You can easily get carried away when trying to test things. For example, if you want to know if your car is working, you could measure the timing of the ignition and put the car on a dynamometer. Or you could just start it and figure that if it runs and moves when you put it in drive, it is probably fine.

When [Thomas Scherrer] wanted to test some tubes, he made the same kind of assumption. While tubes can develop wacky failure modes, the normal difference between a working tube and a failing tube is usually not very subtle. He made a simple test rig to test tubes at DC and one operating point. Not comprehensive, but good enough most of the time. Have a look at what he did in the video below.

The tester is just a few resistors, a tube socket, and some bench power supplies. Of course, you may have to adapt it to whatever tube you are testing. If we had a lot of tubes to do, we might make the rig a bit more permanent, but for an afternoon of testing, what he has would be fine.

In addition to the power supplies, you’ll need at least one, preferably two, volt meters. He was able to validate his results with a proper tube tester. The results matched up well. While this won’t solve all your tube testing problems, it will give you a quick start.

You can build your own modern tube tester, of course. Or pick up a vintage one. Our favorite one uses punched cards.

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Getting A Rise With Laser Cutting

July 7, 2023 by Al Williams 6 Comments

Your first 3D print probably seemed pretty amazing. But if you revisit it after a few years, you’ll likely notice it wasn’t nearly as good as you thought. We improve our printers and our processes and the new better results become normal. If you have a laser cutter, you may go through the same iteration. At first, you are happy just to get scorch marks on the workpiece. But when you move to cutting, you want cleaner cuts. You put tape over the work, add air assist, and invest in a honeycomb bed. Each step gets you better results, but you can always improve.

[The Louisiana Hobby Guy] (also known as [Rich]) knows a lot about the practical side of lasers. He suggests using standoff pins to not just secure the part to the honeycomb bed but lift it up a little, allowing air to flow under the part and lets the laser easily cut all the way through. You can see them in action in the video below.

This is a cheap upgrade to prevent flashback when cutting. [Rich] explains how to size them properly and even how to make your own if you don’t want to buy them off the shelf. You can laser cut hold-down pins from plans [Rich] provides, although he prefers to 3D print them, and you can do that, too. Most beds look similar, but if yours is an oddball, you might have to modify them slightly. He has regular dog clamps and the antiflashback standoffs, so you can make some of each. You can also buy them online. Most do not have the antiflashback feature, but at least one vendor that [Rich] points out does have them

If you don’t like the ones [Rich] shows, you can find 3D models for similar pins in the usual places. You can also design them yourself if you want them exactly how you want.

A good thing to add to your laser cutting workflow. [Rich’s] channel is full of great stuff. If you want to know more about air assist, we’ve added it to our cutters. If you are serious about precision cuts, know your kerf, too.

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Exploring A New Frontier: Desktop EDM Is Coming

July 5, 2023 by Tom Nardi 27 Comments

To say that desktop 3D printing had a transformative effect on our community would be something of an understatement. In just a decade or so, we went from creaky printers that could barely extrude a proper cube to reliable workhorses that don’t cost much more than a decent cordless drill. It’s gotten to the point that it’s almost surprising to see a project grace these pages that doesn’t include 3D printed components in some capacity.

There’s just one problem — everything that comes out of them is plastic. Oh sure, some plastics are stronger than others…but they’re still plastic. Fine for plenty of tasks, but certainly not all. The true revolution for makers and hackers would be a machine that’s as small, convenient, and as easy to use as a desktop 3D printer, but capable of producing metal parts.

If Cooper Zurad has his way such a dream machine might be landing on workbenches in as little as a month, thanks in part to the fact that its built upon the bones of a desktop 3D printer. His open source Powercore device allows nearly any 3D printer to smoothly cut through solid metal using a technique known as electrical discharge machining (EDM). So who better to helm this week’s Desktop EDM Hack Chat?

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