Conductive Gel Has Potential

There are some technologies first imagined in the Star Trek universe have already come to exist in the modern day. Communicators, tablet computers, and computer voice recognition are nearly as good as seen in the future, and other things like replicators and universal translators are well on their way. Star Trek: Voyager introduced a somewhat ignored piece of futuristic technology, the bio-neural gel pack. Supposedly, the use of an organic gel improved the computer processing power on the starship. This wasn’t explored too much on the series, but [Tom] is nonetheless taking the first steps to recreating this futuristic technology by building circuitry using conductive gel.

[Tom]’s circuitry relies on the fact that salts in a solution can conduct electricity, so in theory filling a pipe or tube with a saline solution should function similarly to a wire. He’s also using xanthan gum to increase viscosity. While the gel mixture doesn’t have quite the conductivity of copper, with a slight increase in the supplied voltage to the circuit it’s easily able to be used to light LEDs. Unlike copper, however, these conductive gel-filled tubes have some unique properties. For example, filling a portion of the tube with conductive gel and the rest with non-conductive mineral oil and pushing and pulling the mixture through the tube allows the gel to move around and engage various parts of a circuit in a way that a simple copper wire wouldn’t be able to do.

In this build specifically, [Tom] is using a long tube with a number of leads inserted into it, each of which correspond to a number on a nixie tube. By moving the conductive gel, surrounded by mineral oil, back and forth through the tube at precise intervals each of the numbers on the nixie tube can be selected for. It’s not yet quite as good as the computer imagined in Voyager but it’s an interesting concept nonetheless, not unlike this working replica of a communicator badge.

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How To Solder To Aluminum, Easily

[Ted Yapo] shared a method of easily and conveniently soldering to aluminum, which depends on a little prep work to end up only slightly more complex than soldering to copper. A typical way to make a reliable electrical connection to aluminum is to use a screw and a wire, but [Ted] shows that it can also be done with the help of an abrasive and mineral oil.

Aluminum doesn’t solder well, and that’s because of the oxide layer that rapidly forms on the surface. [Ted]’s solution is to scour the aluminum with some mineral oil. The goal is to scrape away the oxide layer on the aluminum’s surface, while the mineral oil’s coating action prevents a new oxide layer from immediately re-forming.

After this prep, [Ted] uses a hot soldering iron and a blob of solder, heating it until it sticks. A fair bit of heat is usually needed, because aluminum is a great heat conductor and tends to be lot thicker than a typical copper ground plane. But once the aluminum is successfully tinned, just about anything can be soldered to it in a familiar way.

[Ted] does caution that mineral oil can ignite around 260 °C (500 °F), so a plan should be in place when using this method, just in case the small amount of oil catches fire.

This looks like a simple technique worth remembering, and it seems easier than soldering by chemically depositing copper onto aluminum.

Something’s Fishy About This Computer

Aquariums are amazingly beautiful displays of vibrant ocean life, or at least they can be. For a lot of people aquariums become frustrating chemistry battle to keep the ecosystem heathly and avoid a scummy cesspool where no fish want to be.

This hack sidesteps that problem, pulling off some of the most beautiful parts of a living aquarium, while keeping your gaming rig running nice and cool. That’s right, this tank is a cold mineral oil dip for a custom PC build.

It’s the second iteration [Frank Zhao] has built, with many improvements along the way. The first aquarium computer was shoe-horned inside of a very tiny aquarium — think the kind for Beta fish. It eventually developed a small crack that spread to a bigger one with a lot of mineral oil to clean up. Yuck. The new machine has a much larger tank and laser cut parts which is a step up from the hand-cut acrylic of the first version. This makes for a very nice top bezel that hangs the PC guts and provides unobtrusive input and output ports for the oil circulation. A radiator unit hidden out of sight cools the oil as it circulates through the system.

These are all nice improvements, but it’s the aesthetic of the tank itself that really make this one special. The first version was so cramped that a couple of sad plastic plants were the only decoration. But now the tank has the whole package, with coral, more realistic plants, a sunken submarine, and of course the treasure chest bubbler. Well done [Frank]!

Waterproofing The Best Watch Ever Made

The Casio F-91W is probably the most popular wristwatch ever made. It’s been in production forever, it’s been worn by presidents, and according to US Army intelligence it is “the sign of al-Qaeda”. There’s a lot of history in this classic watch. That said, there is exactly one problem with this watch: it’s barely water resistant. [David] thought he had a solution to this problem, and it looks like he may have succeeded. This classic watch is now waterproof, down to 700 meters of depth. If you’re ever 700 meters underwater, you have bigger problems than a watch that isn’t waterproof.

The basic idea of this hack is to replace the air inside the watch with a liquid. This serves two purposes: first, the front glass won’t fog up. Second, liquids are generally incompressible, or at least only slightly compressible. By replacing the air in the watch with mineral oil, the watch is significantly more water resistant.

Filling a watch with mineral oil is done simply by disassembling the watch, submerging it in a dish of mineral oil, and carefully reassembling the watch. Does it work? Don’t know about this watch, but this was done to another classic Casio watch and tested to 1200 psi. That’s a kilometer underwater, and the watch still worked afterward. We’ll take that as a success, although again if you’re ever a kilometer underwater, you have bigger problems than a broken watch.

Extreme Pi Overclocking With Mineral Oil

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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Testing cooling with transformer oil

Measuring The Cooling Effect Of Transformer Oil

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.

Thermal measurement resultsHe 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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Liquid cooled Raspberry Pi with mineral oil

Liquid Cooling Overclocked Raspberry Pi With Style

[HydroGraphix HeadQuarters] has earned his name with this one. While he is using mineral oil instead of hydro, he’s certainly done a nice job with the graphics of it. The ‘it’ in questions is an overclocked Raspberry Pi 3 in a transparent container filled with mineral oil, and with a circulating fan.

He’s had no problem running the Pi at 1.45 GHz while running a Nintendo 64 emulator, getting between 40 °C and 50 °C. The circulating fan is a five volt computer USB fan. It’s hard to tell if the oil is actually moving, but we’re pretty sure we see some doing so near the end of the video below the break.

Mineral oil is not electrically conductive, and is often used to prevent arcing between components on high voltage multiplier boards, but those components are always soldered together. If you’ve ever worked with mineral oil, you know that it creeps into every nook and cranny, making us wonder if it might work its way between some of the (non-soldered) contacts in the various USB connectors on this Raspberry Pi. Probably not, but those of us with experience with it can attest to it’s insidiousness.

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