A Deep Dive On Battery Life

July 28, 2023 by 12 Comments

There are all kinds of old wives’ tales surrounding proper battery use floating around in the popular culture. Things like needing to fully discharge a battery every so often, unplugging devices when they’re fully charged, or keeping batteries in the fridge are all examples that have some kernel of truth to them but often are improperly applied. If you really want to know the truth about a specific battery, its behavior, and its features, it helps to dig in and actually take some measurements directly like [Tyler] has done with a vast array of embedded batteries in IoT devices.

[Tyler] is a firmware engineer by trade, so he is deeply familiar with this type of small battery. Battery performance can change dramatically under all kinds of scenarios, most important among them being temperature. But even the same type of battery can behave differently to others that are otherwise identical, which is why it’s important to have metrics for the batteries themselves and be able to measure them to identify behaviors and possible problems. [Tyler] has a system of best practices in place for monitoring battery performance, especially after things like firmware upgrades since small software changes can often have a decent impact on battery performance.

While working with huge fleets of devices, [Tyler] outlines plenty of methods for working with batteries, deploying them, and making sure they’re working well for customers. A lot of it is extremely useful for other engineers looking to develop large-scale products like this but it’s also good knowledge to have for those of us rolling out our own one-off projects that will operate under battery power. After all, not caring for one’s lithium batteries can have disastrous consequences.

Denim Epoxy Table Is A Work Of Art

July 27, 2023 by 34 Comments

Epoxy has become a hugely popular material in the woodworking and furniture worlds. Who doesn’t love glossy, translucent finishes, after all? [Cam] recently spotted some neat combinations of epoxy with denim, and decided to see if he could replicate the technique to create a very unique desk. We’d say he succeeded.

A significant amount of material was involved, with [Cam] claiming he used 1,000 square feet of denim and 20 gallons of epoxy. The denim was sourced as a bulk roll, making it easy to cut to the proper size to make the desk. Liquid Glass epoxy was used for its visual qualities and its hard-wearing nature.

Combining the two materials was a challenging task. The 50 layers of denim had to be squeegeed one at a time to remove excess epoxy, a process made harder by the thickness of the material. Once all laid up, the stack of denim was compressed between sheets of wood, leading to an epoxy spill of monumental proportions.

Regardless, when the final desk was cleaned up and polished, the results were well worth the trouble. It looks like some kind of crazy denim gem thanks to the rich shine and perfect grain. It’s a material we’d like to play with ourselves.

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How To Survive A Wet Bulb Event

July 27, 2023 by 267 Comments

Territories across the northern hemisphere are suffering through record-breaking heatwaves this summer. Climate scientists are publishing graphs with red lines jagging dangerously upwards as unprecedented numbers pour in. Residents of the southern hemisphere watch on, wondering what the coming hot season will bring.

2023 is hinting at a very real climate change that we can’t ignore. As the mercury rises to new heights, it’s time to educate yourself on the very real dangers of a wet bulb event. Scientists predict that these deadly weather conditions could soon strike in the hottest parts of the world. What you learn here could end up saving your life one day.

Hot Bodies

The body has methods of maintaining a set temperature. Credit: Wikimedia Commons, CNX OpenStax, CC BY-SA 4.0

To understand the danger of a wet bulb event, we must first understand how our bodies work. The human body likes to maintain its  temperature at approximately 37 °C (98.6 °F). That temperature can drift slightly, and the body itself will sometimes move its temperature setpoint higher to tackle infection, for example. The body is a delicate thing, however, and a body temperature above 40 °C (104 °F) can become life threatening. Seizures, organ failures, and unconsciousness are common symptoms of an overheating human. Death is a near-certainty if the body’s temperature reaches 44 °C (112 °F), though in one rare case, a patient in a coma survived a body temperature of 46.5 °C (115.7 °F).

Thankfully, the body has a host of automated systems for maintaining its temperature at its chosen set point. Blood flow can be controlled across the body, and we instinctively seek to shed clothes in the heat and cover ourselves in the cold. However, the bare naked fact is that one system is most crucial to our body’s ability to cool itself. The perspiration system is vital, as it uses sweat to cool our body via evaporation. Water is a hugely effective coolant in this way, with beads of sweat soaking up huge amounts of heat from our skin as they make the phase change from liquid to vapor.

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Running A Modern Graphics Card In A 33 MHz PCI Slot

July 26, 2023 by 21 Comments

If you ever looked at a PCI to PCIe x16 adapter and wondered what’d happen if you were to stick a modern PCIe GPU in it, the answer apparently is ‘it works’ according to an attempt by [Circuit Rewind]. As long as you accept needing to supply external power with even a low-end GT 1030 card – as the PCI slot cannot provide enough power – and being limited to a single PCIe lane. This latter point isn’t so much of an issue as a single PCIe lane offers more bandwidth than the (shared) PCI bus anyway.

Despite the somewhat improvised setup, the GT 1030 card provided a decent 1080p experience in a range of games, after removing half of the 8 GB of system RAM before the configuration would work, probably due to VRAM mapping issues. Since the mainboard used also offered PCIe, the same card was run in a PCIe x4 slot, as well as in an x1 configuration, both with noticeably higher performance and putting the ‘why’ in ‘try’.

Perhaps unsurprisingly, a RTX 3080 also booted fine with external power and only 4 GB system RAM installed. Despite the PCIe x1 link, the system was able to finish a 3D benchmark and play Doom 2016, but with only 4 GB of system RAM and an old Athlon quad-core CPU, it was a terrible experience. Perhaps the most fascinating lesson to learn from this is that PCI and PCIe are amazingly compatible with only a simple translation bridge, even if high-performance graphics aren’t quite what PCI was meant for. After all, that’s why we got cursed with AGP for many years.

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3D-Printed RC Skid Steer Is Cute Construction Machinery Done Right

July 26, 2023 by 11 Comments

Skid steers are great fun if you get to drive one on a construction site. [ProfessorBoots] has long been a fan of the diminutive diggers, and decided to make a 3D-printed version for his own pleasure.

The build uses a chassis printed in several colors which adequately recreates the charms of a full-sized skid steer. The brains of the operation is an ESP32, which receives commands over WiFi for remote control. A pair of geared N20 brushed motors are driven from a small H-bridge controller, each one driving one side of the skid steer. A toothed belt was 3D printed to allow each motor to drive two wheels on one side. Meanwhile, a pair of servos are charged with both lifting and tilting the bucket. Yes, you heard correctly – you can actually pick up and carry objects around your desk with this thing.

It’s a neat build and could be your introduction into the world of RC construction machines. Video after the break.

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A wooden spin coating machine sitting on a desk

Hackaday Prize 2023: Homebrew Spin Coater Makes Micrometer-Thin Layers

July 26, 2023 by 10 Comments

One of the great things about the Gearing Up challenge of the 2023 Hackaday Prize is that it lets you discover tools that you don’t encounter every day. We had never given much thought to spin coaters, for example, until we saw [Jeroen Delcour]’s neat homebrew example. As it turns out, spin coating has lots of applications in fields like optics, semiconductor manufacturing or even art projects, where a thin, even layer of a material is required on top of a flat substrate.

The basic idea behind a spin coater is simple: you dispense a few drops of a solution containing the material to be deposited on top of the thing you want to coat, then spin the thing around at a constant speed. The balance between the centripetal force and the liquid’s surface tension ensures that the liquid turns into a film with a consistent thickness all across the substrate. The solvent evaporates, and you’re left with a nice solid layer just a few microns thick.

[Jeroen] built his spin coater out of a brushless DC drone motor, a programmable motor controller, and an ESP32. A rotary pushbutton and an OLED form the user interface, allowing the user to select the speed and spin times. The electronics are all mounted inside a laser-cut wooden enclosure, with the motor sticking out the top, surrounded by a 3D-printed splash guard.

Professional spin coating equipment typically comes with a vacuum chuck to hold the sample in place, but [Jeroen] wasn’t too excited about implementing vacuum systems on a spinning platform and decided instead to simply clamp down the sample using screws in a laser-cut piece of acrylic. This works well enough, and is easy to customize for different sample sizes.

In the video embedded below, [Jeroen] experiments with applying a layer of silicone rubber onto a PCB. Spin coating is an essential step when you’re making your own semiconductor devices such as solar cells, though you might also need more complicated equipment such as an electron microscope. [Jeroen]’s spin coater is at least able to process much larger objects than one we saw earlier.

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Adding Two Axes Makes CNC Router More Than The Sum Of Its Parts

July 26, 2023 by 20 Comments

The problem with building automated systems is that it’s hard to look at any problem and not see it in terms of possible automation solutions. Come to think of it, that’s probably less of a bug and more of a feature, but it’s easy to go overboard and automate all the things, which quickly becomes counterproductive in terms of time and money.

If you’re clever, though, a tactical automation solution can increase your process efficiency without breaking the budget. That’s where [Christopher Helmke] seems to have landed with this two-axis add-on fixture for his CNC router. The rig is designed to solve the problem of the manual modification needed to turn off-the-shelf plastic crates into enclosures for his line of modular automation components, aspects of which we’ve featured before. The crates need holes drilled in them and cutouts created in their sides for displays and controls. It’s a job [Christopher] tackled before with a drill and a jigsaw, with predictable results.

To automate the job without going overboard, [Christopher] came up with a tilting turntable that fits under the bed of the CNC router and sticks through a hole in the spoil board. The turntable is a large, 3D printed herringbone gear driven by a stepper and pinion gear. A cheap bearing keeps costs down, while a quartet of planetary gears constrain the otherwise wobbly platform. The turntable also swivels 90 degrees on a herringbone sector gear; together, the setup adds pitch and roll axes to the machine that allow the spindle access to all five sides of the crates.

Was it worth the effort? Judging by the results in the video below, we’d say so, especially given the number of workpieces that [Christopher] has to process. Add in the budget-conscious construction that doesn’t sacrifice precision too much, and this one seems like a real automation win.

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