Near-Silent Bellows Uses Water Flow And Magnetic Coupling

Fan noise is a contentious issue among the computer community. Some don’t notice it, others rage against it as an annoyance and distraction. Some turn to liquid cooling, while others look to passive solutions to eliminate the scourge. [Matt] of [DIY Perks] may have found a far more oddball solution, however.

The build is essentially a giant bellows, but the manner in which it operates is unlike anything we’ve seen previously. To shift the large pusher plate inside back and forth, [Matt] initially experimented with building his own linear motor out of coils and magnets. After that failed, he began to tinker with a system of moving a magnet back and forth through a tube with water pressure from a pump, which would then drive the pusher plate through magnetic coupling. This looked promising, but reversing the flow proved difficult. After building his own set of water valves to change the flow direction, the bellows began to work slowly, but with limited performance. Realizing the valves weren’t up to scratch, [Matt] rebuilt the system with 10 pumps, set up in two banks of 5. With the pumps hooked up in series, they supplied plenty of pressure to force the bellows back and forth. Reed switches were used to reverse the flow at either end to make the bellows run continuously.

In testing, the bellows compared well with a bank of four large case fans, though at 20 times the size. Suffice to say this is not exactly a compact solution. We look forward to seeing [Matt] do more with the bellows, with his intention being to use it as the primary cooling system for a computer. Of course, if this looks too complex, you could always consider a mineral oil setup instead. Video after the break.

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Fail Of The Week: How Not To Watercool A PC

To those who choose to overclock their PCs, it’s often a “no expense spared” deal. Fancy heat sinks, complicated liquid cooling setups, and cool clear cases to show off all the expensive guts are all part of the charm. But not everyone’s pockets are deep enough for off-the-shelf parts, so experimentation with cheaper, alternatives, like using an automotive fuel pump to move the cooling liquid, seems like a good idea. In practice — not so much.

The first thing we thought of when we saw the title of [BoltzBrain]’s video was a long-ago warning from a mechanic to never run out of gas in a fuel-injected car. It turns out that the gasoline acts as a coolant and lubricant for the electric pump, and running the tank dry with the power still applied to the pump quickly burns it out. So while [BoltzBrain] expected to see corrosion on the brushes from his use of water as a working fluid, we expected to see seized bearings as the root cause failure. Looks like we were wrong: at about the 6:30 mark, you can see clear signs of corrosion on the copper wires connecting to the brushes. It almost looks like the Dremel tool cut the wire, but that green copper oxide is the giveaway. We suspect the bearings aren’t in great shape, either, but that’s probably secondary to the wires corroding.

Whatever the root cause, it’s an interesting tour inside a common part, and the level of engineering needed to build a brushed motor that runs bathed in a highly flammable fluid is pretty impressive. We liked the axial arrangement of the brushes and commutator especially. We wonder if fuel pumps could still serve as a PC cooler — perhaps changing to a dielectric fluid would do the trick.

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