Keep Both Hands On The Probes With This Oscilloscope Footswitch

We’ve got two hands, so it’s natural to want to use both of them while diagnosing a circuit with an oscilloscope. Trouble is, keeping both hands on the probes makes it a touch difficult to manipulate the scope. If only there were some way to put your idle lower appendages to work.

This multipurpose oscilloscope footswitch interface makes so much sense that we wonder why such a thing isn’t standard equipment on more scopes. [Paul Roukema]’s interface relies on the USB Test and Measurement Class (USBTMC) protocol that allows most modern scopes to be remotely controlled, somewhat like the General Purpose Interface Bus (GPIB) protocol of old. [Paul]’s interface uses an STM32 microcontroller to talk USBTMC to either Keysight’s Infinium scopes or the Tektronix DPO line, since those were what he had to test against. Tapping the footswitch cycles the acquisition mode on and off or triggers a single acquisition. He’s thoughtfully included the USBTMC specs in his GitHub project, so adapting it to other scopes should be straightforward. We’d even wager that older scopes with GPIB could enjoy the same handsfree control.

Have a down-market scope but still want to go handsfree? [Jenny List]’s primer on running a Rigol with Python might offer some hints on where to start.

CNC Machine Most Satisfyingly Mills Double-Sided PCBs

We know that by this point in the development of CNC technology, nothing should amaze us. We’ve seen CNC machines perform feats of precision that shouldn’t be possible, whether it be milling a complex jet engine turbine blade or just squirting out hot plastic. But you’ve just got to watch this PCB milling CNC machine go through its paces!

The machine is from an outfit called WEGSTR, based in the Czech Republic. While it appears to be optimized for PCB milling and drilling, the company also shows it milling metals, wood, plastic, and even glass. The first video below shows the machine milling 0.1 mm traces in FR4; the scale of the operation only becomes apparent when a gigantic toothbrush enters the frame to clear away a little swarf. As if that weren’t enough, the machine then cuts traces on the other side of the board; vias created by filling drilled holes with copper rivets and peening them over with a mandrel and a few light hammer taps connect the two sides.

Prefer your boards with solder resist and silkscreening? Not a problem, at least judging by the second video, which shows a finished board getting coated with UV-cure resist and then having the machine mill away just the resist on the solder pads. We’re not sure how they deal with variations in board thickness or warping, but they sure have it dialed in. Regardless of how they optimized the process, it’s a pleasure to watch.

At about $2,600, these are not cheap machines, but they may make sense for someone needing high-quality boards with rapid turnaround. And who’s to say a DIY machine couldn’t do as good a job? We’ve seen plenty of them before, and covered the pros and cons of etching versus milling too.

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1,000 Watt Power Supply Tear Down And Repair

[TheSignalPath] wanted to repair a broken Instek PSW80-40.5 because it has a lot of output for a programmable power supply — 1,080 watts, to be exact. This isn’t a cheap supply — it looks like it costs about $2,200 new. The unit wasn’t working and when he took it apart, he found a nasty surprise. There is a base PCB and three identical power supply modules, and virtually no access without disconnecting the boards. He continued the teardown, and you can see the results in the video below.

Each of the power supply modules are two separate PCBs and the design has to account for the high currents required. The power supply is a switching design with some filtering on the motherboard. One of the boards of the power supply module rectifies the incoming line voltage to a high DC voltage (about 400 volts). The second board then does DC to DC conversion to the desired output.

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Professional Results From Cheap Air Compressors

The portable air compressors sold at big box hardware stores like Lowe’s and Home Depot are perfectly suited for the jobs they’re advertised for: namely throwing some nails into the wall or filling tires. But if you try to respray your car with that $50 Black Friday pancake air compressor, you’re going to have a bad day. The relatively small amount of air they hold is almost guaranteed to be contaminated with oil and moisture, making it unsuitable for painting or even just blowing the dust out of electronics.

But all is not lost. [Stephen Saville] has done an excellent job documenting his work to turn these low cost homeowner-grade air compressors into something suitable for spraying auto body panels. But even if you aren’t looking to put a sick pearlescent finish on the family minivan, these tips are worth checking out. From increasing the usable volume of air in the system to separating out contaminants, these modifications can unlock a whole new world of pneumatic projects.

The big one (literally and figuratively) is the swirl tube [Stephen] builds out of an old CO2 cylinder. The idea is that this will centrifugally clean the air, not unlike a cyclonic dust separator. As the air enters the top of the cylinder and spins around, contact with the cold metal will cause any moisture to condense out and collect down at the bottom. Oil and other particles in the air should also get spun out, leaving a central column of cleaner air. The collected water and contaminants at the bottom can be occasionally purged out by way of the cylinder’s original valve.

With a source of clean and dry air sorted, [Stephen] next wanted a way to get it around his shop. Using scrap metal pipes he puts together a system that not only gives him air where he needs it, but also increases the volume of compressed air he has available. By using large smooth metal pipes rather than something like flexible rubber hose, the plumbing puts very little resistance on air flow. The pipes therefore can be considered something of an extension of the compressor’s primary tank.

In the video after the break, [Stephen] shows off his new air system by laying down a very nice looking coat of paint on a car hood, but he also goes through the whole build process if you want to see the nuts and bolts of his system. He gives some great tips on welding and working with dissimilar metals which are worth the price of admission alone.

Outfitting the workshop with an integrated compressed air system sounds like the perfect second project to tackle once you’ve got the built-in dust collection system up and running.

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Reverse Engineering With Sandpaper

Every once in a while, and more so now than before, you’ll find a really neat chip with zero documentation. In [David]’s case, it’s a really cool USB 3.0 eMMC/ SD MMC controller. Use this chip, attach a USB port on one end, and some memory on the other, and you have a complete bridge. There are drivers, too. There are products shipping with this chip. The problem is, there is no data sheet. Wanting to use this chip, [David] turned to sandpaper to figure out the pinout of this chip.

The best example of a product that came with this chip is a simple board from the hardkernel store that happily came with fairly high resolution product photos. While waiting for these boards to be delivered, [David] traced the top layer of copper. This was enough to get an idea of what was going on, but the real work started when the boards arrived. These were placed in a flatbed scanner and carefully photographed.

The next step was to desolder all the parts, taking care to measure and catalog each component. Then, it’s off to sanding with 200 and 600 grit wet sandpaper. Slowly, the soldermask is removed and the top copper layer appears. After that, it’s just a matter of sanding and scanning, stacking all the layers together with your image processing software of choice.

There are a few caveats to hand-sanding a PCB to reverse-engineer the copper layers. First, it makes a mess. This is wet/dry sandpaper, though, and you can and should sand with water. Secondly, even pressure should be applied. We’re not sure if [David] was holding the sandpaper or not, but the best technique is to actually hold the board itself.

Despite a few problems, [David] did get the pictures of each copper layer. After assembling these images, he could make an Eagle part for an eMMC reader for his Nintendo Switch.

Overlooked Minimalism In Assistive Technology

If your eyes are 20/20, you probably do not spend much time thinking about prescription eyeglasses. It is easy to overlook that sort of thing, and we will not blame you. When we found this creation, it was over two years old, but we had not seen anything quite like it. The essence of the Bear Paw Assistive Eating Aid is a swiveling magnet atop a suction cup base. Simple right? You may already be thinking about how you could build or model that up in a weekend, and it would not be a big deal. The question is, could you make something like this if you had not seen it first?

Over-engineered inventions with lots of flexibility and room for expansion have their allure. When you first learn Arduino, every problem looks like a solution for that inexpensive demo board and one day you find yourself wearing an ATMEGA wristwatch. Honestly, we love those just as much but for an entirely different reason. When all the bells and whistles are gone, when there is nothing left but a robust creation that, “just works,” you have created something beautiful. Judging by the YouTube comments of the video, which can be seen below the break, those folks have no trouble overlooking the charm of this device since the word “beard” appears 95 times and one misspelling for a “bread” count of one. Hackaday readers are a higher caliber and should be able to appreciate its elegance.

The current high-tech solution for self-feeding is a robot arm, not unlike this one which is where our minds went when we heard about an invention about eating without using hands, and we will always be happy to talk about robot arms.

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PLA Foils Homemade Tachometer

[Integza] built a Tesla turbine and wanted to know how fast it was spinning. However, he didn’t have a tachometer, and didn’t want to buy one. After a false start of trying to analyze the audio to measure the speed, he decided to use a tried-and-true method. Let the wheel break an infrared (IR) optointerruptor and count the spokes of the wheel as they go by. If you know the spacing between the spokes, you can compute the speed. There was only one problem: it didn’t work.

Turns out, PLA is at least somewhat transparent to IR. Knowing that it was a simple matter to fix some tape to the wheel that would block IR and that made things work much better. If you missed the video where he built the turbine, you might want to watch it first.

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