hardware

1715 Articles

Fail Of The Week: How Not To Re-Reflow

October 10, 2019 by 30 Comments

There’s no question that surface-mount technology has been a game-changer for PCB design. It means easier automated component placement and soldering, and it’s a big reason why electronics have gotten so cheap. It’s not without problems, though, particularly when you have no choice but to include through-hole components on your SMT boards.

[James Clough] ran into this problem recently, and he tried to solve it by reflowing through-hole connectors onto assembled SMT boards. The boards are part of his electronic lead screw project, an accessory for lathes that makes threading operations easier and more flexible. We covered the proof-of-concept for the project; he’s come a long way since then and is almost ready to start offering the ELS for sale. The PCBs were partially assembled by the board vendor, leaving off a couple of through-hole connectors and the power jack. [James]’ thought was to run the boards back through his reflow oven to add the connectors, so he tried a few experiments first on the non-reflow rated connectors. The Phoenix-style connectors discolored and changed dimensionally after a trip through the oven, and the plastic on the pin headers loosened its grip on the pins. The female header socket and the power jack fared better, so he tried reflowing them, but it didn’t work out too well, at least for the headers. He blames poor heat conduction due to the lack of contact between the board and the reflow oven plate, and we agree; perhaps an aluminum block milled to fit snugly between the header sockets would help.

Hats off to [James] for trying to save his future customers a few steps on assembly, but it’s pretty clear there are no good shortcuts here. And we highly recommend the electronic leadscrew playlist to anyone interested in the convergence of machine tools and electronics.

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The Cutest Oscilloscope Ever Made

October 10, 2019 by 11 Comments

If you thought your handheld digital oscilloscope was the most transportable of your signal analyzing tools, then you’re in for a surprise. This oscilloscope made by [Mark Omo] measures only one square inch, with the majority of the space taken up by the OLED screen.

It folds out into an easier instrument to hold, and admittedly does require external inputs, so it’s not exactly a standalone tool. The oscilloscope runs on a PIC32MZ EF processor, achieving 20Msps and 1MHz of bandwidth. The former interleaves the processor’s internal ADCs in order to achieve its speed.

For the analog front-end the signals first enter a 1M ohm terminator that divide the signals by 10x in order to measure them outside the rails. They then get passed through a pair of diodes connected to the rails, clamping the voltage to prevent damage. The divider centers the incoming AC signal around 1.65V, halfway between AGND and +3.3V. As a further safety feature, a larger 909k Ohm resistor sits between the signals and the diodes in order to prevent a large current from passing through the diode in the event of a large voltage entering the system.

The next component is a variable gain stage, providing either 10x, 5x, or 1x gain corresponding to 1x, 0.5x, and 0.1x system gains. For the subsystem, a TLV3541 op-amp and ADG633 tripe SPDT analog switch are used to provide a power bandwidth around the system response due to driving concerns. Notably, the resistance of the switch is non-negligible, potentially varying with voltage. Luckily, the screen used in the oscilloscope needs 12V, so supplying 12V to the mux results in a lower voltage and thus a flatter response.

The ADC module, PIC32MZ1024EFH064, is a 12-bit successive approximation ADC. One advantage of his particular ADC is that extra bits of resolution only take constant time, so speed and accuracy can be traded off. The conversion starts with a sample and hold sequence, using stored voltage on the capacitor to calculate the voltage.

Several ADCs are used in parallel to sample at the same time, resulting in the interleaving improving the sample rate. Since there are 120 Megabits per second of data coming from the ADC module, the Direct Memory Access (DMA) peripheral on the PIC32MZ allows for the writing of the data directly onto the memory of the microcontroller without involving the processor.

The firmware is currently available on GitHub and the schematics are published on the project page.

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Building A Wind Power Generator In Your Backyard

October 5, 2019 by 53 Comments

For many environmental enthusiasts, horizontal-axis wind turbines (HAWTs) — the kind that look like windmills slowly spinning in the distance — are a pretty familiar sight. Unfortunately, there are quite a few caveats that make them harder to adopt despite the fact that harvesting renewable energy sources is more sustainable than relying on natural gas and fuels that can be depleted. Since they face in one axis, they need to be able to track the wind, or else trade off the ability to maximize energy output. In turbulent and gusty conditions, as well, HAWTs face accelerated fatigue when harvesting.

The development of the vertical-axis wind turbine (VAWT) solves several of these issues. In addition, the turbines are typically closer to the ground and the gearbox replacement is simpler and more efficient. Maintenance is more accessible due to the size of the turbines, so no heavy machinery is typically necessary to access crucial components on-site. In addition, the gearbox by nature of its operation takes on less fatigue and is able to function in turbulent winds, which reduces the rate of failure.

For a simple version of a VAWT that you can build yourself, [BlueFlower] has published several mechanical drawings that detail the layout of the design. The wind power generator uses 24 magnets, copper wire fashioned into coils, and a metal plate for the main generator. The coils are arranged in a circular formation on a static plate, while the magnets are equally spaced on a moving circular plate. As the magnets pass over coils, the flux induces a current, which increases as the plates spin faster.

The blades of the generator are made from blue foam with a metal bar running through it for structure. Three of the blades are attached with triangular bars to a central rod, which also holds the spinning magnetic plate.

In [BlueFlower]’s initial trials using the VAWT for charging a battery they were able to generate a max power of 15W on boost mode and 30-70W when charging in PWM mode. Not bad for a home-made wind power generator!

There aren’t only pros to the design, however. While VAWTs may be cheaper, more mobile, and more resistant to wear and tear, there are some design features that prevent the generators from functioning as well as HAWTs at harvesting energy. The blades don’t produce torque at the same time, with some blades simply being pushed along. This produces more drag on the blades when they rotate, limiting the efficiency of the entire system. In addition, higher wind speeds are typically found at higher altitudes, so the VAWTs will perform better if installed on a towering structure. Vibration forces close to the ground can also wear out the bearings, resulting in more maintenance and costs.

 

 

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Solve Your Precision Woes With A Sliding Angle Grinder

October 3, 2019 by 9 Comments

Angle grinders are among the most useful tools for anyone who’s ever had to cut metal. They’re ergonomic, compact, and get the job done. Unfortunately, one of the tradeoffs you usually make when using them is precision.

But thankfully, there’s a DIY solution. YouTuber [workshop from scratch] demonstrated the build process for a sliding angle grinder in a recent video, welding steel beams into a flat frame and attaching fitted beams on top to slide across the rows. Where necessary, spacers are used to ensure that the slider is perfectly fitted to the beam. The contraption holding the angle grinder – a welded piece of steel bolted to the sliding mechanism – has a grip for the user to seamlessly slide the tool across the table.

The operation is like a more versatile and robust chop saw, not to mention the customized angle references you can make to cut virtually anything you like. The build video shows the entire process, from drill pressing and turning holes to welding pieces of the frame together to artfully spray painting the surface a classy black, with familiarity enough to make the project look like a piece of cake.

As the name implies, [workshop from scratch] is all about building your own shop tools, and we’ve previously taken a look at their impressive hydraulic vise and mobile crane builds. These tools, largely hacked together from scraps, prove that setting up your own shop doesn’t necessarily mean you need to break the bank.

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The Righteous Quest To Crack A Canon I9900

October 2, 2019 by 34 Comments

[Starhawk] is a man with a problem. More accurately, he’s a man whose mother has a problem, but ultimately that ends up being the same thing. Her wide-format Canon printer recently stopped working after better than a decade of reliable service, and he wants to know why. Rather than spend the money on buying a new printer, he’s determined to find out if she’s been the victim of planned obsolescence by reverse engineering the Canon i9900 to see what makes it tick (or stop ticking, as the case may be).

In the absence of any obvious hardware faults, [Starhawk] has suspicions that the machine’s QY6-0055 printhead has run over some internal “odometer” and simply turned itself off. We’ve all seen similar trickery at play when trying to use third party ink cartridges in our printers, so it’s certainly not outside the realm of possibility that the Canon i9900 is designed to reject heads once they’ve seen enough usage. Perhaps the biggest clue is that the QY6-0055 has a Seiko S93C56BR EEPROM on the board that’s keeping track of…something.

Right now, [Starhawk] is devoting his energies on trying to make sense of the data he pulled from the EEPROM using his TL866A programmer. But that’s no easy feat with a sample size of just one, which is why he’s looking for help. He’s hoping that other hackers with similar printers (and ideally ones that use the same QY6-0055 head) could submit their own EEPROM dumps and the community could get to work trying to decipher what’s stored on the chips. He’s really hoping that somebody at Canon might be willing to sneak him a couple tips on what he should be looking for, but at this point we think he’ll take whatever assistance he can get.

Now to be fair, there’s really no way to know definitively if there’s some flag stored on the EEPROM that’s keeping the printer from working. It could just be good old fashioned hardware failure, which would hardly be a surprise for a piece of consumer electronics from 2005. But even if the effort to understand the Canon’s EEPROM doesn’t get him any closer to a working printer, we still think it’s a fascinating example of real-world reverse engineering that’s worth it for the experience alone.

There’s a long history of hackers doing battle with their printers, from emulating an ink cartridge with a microcontroller to reinking the ribbon of a vintage 1980s behemoth. We’re interested in seeing where this project takes [Starhawk], but no matter what happens there are likely to be some interesting discoveries made along the way.

Think IN18s Are Cool? Get A Load Of This Must-Have Custom Nixie Tube

October 2, 2019 by 38 Comments

Us: “I’ll take Retro style displays we absolutely have to have for $200, Alex.”

Trebek: “This nixie tube is unlike any conventional tube you’ve seen before, handbuilt and NOT numbers or letters.”

Us: “What is FriendlyWire’s new logo tube?”

Trebek: “Heck yeah.”

Nixie tubes are the vacuum technology that manages to do far less than a graphic LCD while looking about a million times cooler. Generally speaking, these tubes are no longer manufactured, and the old stock you can get your hands on usually contain a set of filaments shaped like numbers. But @FriendlyWire’s tweet of this Nixie tube by [Dalibor Farny] breaks both of those rules. This handmade tube isn’t just a numerical display or a colon display (the punctuation mark, get your head out of the gutter). It’s a custom logo, and it’s beautiful.

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