Free Refrigeration In Hot Climates

August 21, 2020 by Bryan Cockfield 34 Comments

Passive homes are a fairly recent trend in home building, but promise a future with minimal energy inputs in our day-to-day. One of the challenges in this year’s Hackaday Prize is to envision ways to add utility to earthen homes often used in refugee camps where there is a housing crisis. Adding passive utilities to these adobe buildings would be a fantastic upgrade, so [Cat] decided to tackle the challenge by creating a refrigerator that needs no electricity.

The the plan for the device works by using evaporative cooling to reduce the temperature in a small box which can be used for food storage. Of course, using evaporative cooling means that you need ready access to water and it likely won’t work in a humid or cool environment, but systems like these have been in use for centuries in plenty of places around the world. [Cat]’s plan is a little more involved than traditional methods of evaporative cooling though, and makes use of a specially painted chimney which provides the airflow when heated by sunlight.

The project is still in its infancy but it would be interesting to see a proof-of-concept built in a real-life passive house in an arid environment. Unfortunately, those of us in humid (or tropical) environments will have to look elsewhere for energy-efficient cooling solutions.

Porsche’s Printed Pistons Are Powerful And Precise

July 28, 2020 by Kristina Panos 49 Comments

The 700-horsepower Porsche 911 GT2 RS is already pretty darn fast — over three times faster than the average regular-person car on the road today. For the sports car enthusiast, there’s likely no ceiling on the need for speed and performance. And so, Porsche was able to wrangle another thirty horsepower out of their limited-run supercar by printing a set of ultra-lightweight pistons.

Pistons being lasered into existence. Image via The Drive

These pistons are printed from high-purity aluminium alloy powder that was developed by German auto parts manufacturer Mahle. Porsche is having these produced by Mahle in partnership with industrial machine maker Trumpf using the laser metal fusion (LMF) process. It’s a lot like selective laser sintering (SLS), but with metal powder instead of plastic.

The machine dusts the print bed with a layer of powder, and then a laser melts the powder according to the CAD file, hardening it into shape. This process repeats one layer at a time, and supports are zapped together wherever necessary. When the print job is finished, the pistons are machined into their shiny final form and thoroughly tested, just like their cast metal cousins have been for decades. Continue reading “Porsche’s Printed Pistons Are Powerful And Precise” →

Custom Drill Press Table Eliminates Hassles

March 29, 2020 by Bryan Cockfield 7 Comments

Getting a perfect workshop together, with all the right tools, is a dream for many. A lot of us cobble together what we can with a dremel tool, a soldering iron, and whatever work surface happens to be available in the kitchen or spare bedroom. But even when we finally get a permanent garage or shop to work in, there are still some challenges to overcome with our workspaces. [Workshop From Scratch] was having issues with his drill press, and solved them with this custom build.

Rather than modify an existing press, he first welded a table together from scratch using square tube. From there he set about solving those issues. The first was having to make a large number of adjustments up and down when working on larger pieces. For that he added an electrically adjustable worktop which keeps him from having to make constant adjustments of the press itself. The second improvement over the standard press workspace was adding a cooling system for the cutting tools, saving himself money in bits and allowing quicker drilling.

The finished product looks professional thanks to a quality paint job and, of course, having all the right tools in the workshop in the first place to put something like this together. We all have an idea in our heads about the perfect workshop for our own needs, but don’t forget to think outside the box when it comes to building one yourself.

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Tearing Down A $25K 8K Video Camera

June 14, 2019 by Richard Baguley 55 Comments

Most people buy expensive cameras and use them rather than taking them apart, but Linus Tech Tips has a different approach. They decided that they would rather take the camera apart, with a view to converting it to water cooling. Why? Well, that’s perhaps like asking why climb Mount Everest: because it is there. The practicality (or desirability) of water-cooling an 8K camera aside, the teardown is rather interesting from an an engineering point of view. The RED HELIUM 8K costs about $25K, and most of us don’t often get a look inside equipment like this.

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Extreme Pi Overclocking With Mineral Oil

November 30, 2018 by Bryan Cockfield 31 Comments

Liquid cooling is a popular way to get a bit of extra performance out of your computer. Usually this is done in desktops, where a special heat sink with copper tubing is glued to the CPU, and the copper tubes are plumbed to a radiator. If you want dive deeper into the world of liquid cooling, you can alternatively submerge your entire computer in a bath of mineral oil like [Timm] has done.

The computer in question here is a Raspberry Pi, and it’s being housed in a purpose-built laser cut acrylic case full of mineral oil. As a SoC, it’s easier to submerge the entire computer than it is to get a tiny liquid-cooled heat sink for the processor. While we’ve seen other builds like this before, [Timm] has taken a different approach to accessing the GPIO, USB, and other connectors through the oil bath. The ports are desoldered from the board and a purpose-built header is soldered on. From there, the wires can be routed out of the liquid and sealed off.

One other detail used here that we haven’t seen in builds like this before was the practice of “rounding” the flat ribbon cable typically used for GPIO. Back in the days of IDE cables, it was common to cut the individual wires apart and re-bundle them into a cylindrical shape. Now that SATA is more popular this practice has been largely forgotten, but in this build [Timm] uses it to improve the mineral oil circulation and make the build easier to manage.

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Measuring The Cooling Effect Of Transformer Oil

November 15, 2018 by Steven Dufresne 36 Comments

Transformer oil has long served two purposes, cooling and insulating. The large, steel encased transformers we see connected to the electrical grid are filled with transformer oil which is circulated through radiator fins for dumping heat to the surrounding air. In the hacker world, we use transformer oil for cooling RF dummy loads and insulating high voltage components. [GreatScott] decided to do some tests of his own to see just how good it is for cooling circuits.

He started with testing canola oil but found that it breaks down from contact with air and becomes rancid. So he purchased some transformer oil. First, testing its suitability for submerging circuits, he found that he couldn’t see any current above his meter’s 0.0 μA limit when applying 15 V no matter how close together he brought his contacts. At 1 cm he got around 2 μA with 230 VAC, likely from parasitic capacitance, for a resistance of 115 Mohm/cm.

Moving on to thermal testing, he purchased a 4.7 ohm, 100 watt, heatsink encased resistor and attached a temperature probe to it with Kapton tape. Submerging it in transformer oil and applying 25 watts through it continuously, he measured a temperature of 46.8°C after seven minutes. The same test with distilled water reached 35.3°C. Water’s heat capacity is 4187 J/kg∙K, not surprisingly much better than the transformer oil’s 2090 J/kg∙K which in turn is twice as good as air’s 1005 J/kg∙K.

He performed a few more experiments but we’ll leave those to his video below.

We’ve run across a number of tests running boards submerged in various oils before. For example, we’ve seen Raspberry Pi’s running in vegetable oil and mineral oil as well as an Arduino running in a non-conductive liquid coolant, all either overclocked or under heavy load.

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A Look At Liquid Dielectrics

September 18, 2018 by Dan Maloney 35 Comments

One evening quite a few years ago, as I was driving through my hometown I saw the telltale flashing lights of the local volunteer fire department ahead. I passed by a side road where all the activity was: a utility pole on fire. I could see smoke and flames shooting from the transformer and I could hear the loud, angry 60 Hz buzzing that sounded like a million hornet nests. As I passed, the transformer exploded and released a cloud of flaming liquid that rained down on the road and lawns underneath. It seemed like a good time to quit rubbernecking and beat it as fast as I could.

I knew at the time that the flaming liquid was transformer oil, but I never really knew what it was for or why it was in there. Oil is just one of many liquid dielectrics that are found in a lot of power distribution equipment, from those transformers on the pole to the big capacitors and switchgear in the local substation. Liquid dielectrics are interesting materials that are worth taking a look at.

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