vacuum

140 Articles

Robots Talking To Robots

February 7, 2026 by 5 Comments

Although there are a few robots on the market that can make life a bit easier, plenty of them have closed-source software or smartphone apps required for control that may phone home and send any amount of data from the user’s LAN back to some unknown server. Many people will block off Internet access for these types of devices, if they buy them at all, but that can restrict the abilities of the robots in some situations. [Max]’s robot vacuum has this problem, but he was able to keep it offline while retaining its functionality by using an interesting approach.

Home Assistant, a popular open source home automation system, has a few options for voice commands, and can also be set up to transmit voice commands as well. This robotic vacuum can accept voice commands in lieu of commands from its proprietary smartphone app, so to bypass this [Max] set up a system of automations in Home Assistant that would command the robot over voice. His software is called jacadi and is built in Go, which uses text-to-speech to command the vacuum using a USB speaker, keeping it usable while still offline.

Integrating a voice-controlled appliance like this robotic vacuum cleaner allows things like scheduled cleanings and other commands to be sent to the vacuum even when [Max] isn’t home. There are still a few limitations though, largely that communication is only one way to the vacuum and the Home Assistant server can’t know when it’s finished or exactly when to send new commands to the device. But it’s still an excellent way to keep something like this offline without having to  rewrite its control software entirely.

A pair of glass vacuum tubes can be seen on a workbench, each with complex copper structures inside. One is mounted on top of a metal chassis with a motor and some other circuitry visible.

Taking A Look At Variable Vacuum Capacitors

January 11, 2026 by 20 Comments

Variable capacitors may be useful, but the air gap that provides their capacitance is their greatest weakness. Rather than deal with the poor dielectric properties of air, some high-end variable capacitors replace it with a vacuum, which presents some obvious mechanical difficulties, but does give the resulting capacitor a remarkable quality factor, high-voltage performance, and higher capacitance for plate area than their air-gapped brethren. [Shahriar] of [The Signal Path] managed to acquire a pair of these and took a detailed look at their construction and performance in a recent video.

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Oil-Based Sprengel Pump Really Sucks

September 17, 2025 by 21 Comments

Have you heard of the Sprengel pump? It’s how they drew hard vacuum back before mechanical pumps were perfected — the first light bulbs had their vacuums drawn with Sprengel pumps, for example. It worked by using droplets of a particular liquid to catch air particles, and push them out a narrow tube, thereby slowly evacuating a chamber. The catch is that that liquid used to be mercury, which isn’t something many of us have on hand in kilogram quantities anymore. [Gabriel Wolffe] had the brainwave that one might substitute modern vacuum pump oil for mercury, and built a pump to test that idea.

Even better, unlike the last (mercury-based) Sprengel pump we saw, [Gabriel] set up his build so that no glassblowing is required. Yes, yes, scientific glassblowing used to be an essential skill taught in every technical college in the world. Nowadays, we’re glad to have a design that lets us solder brass fittings together. Technically you still have to cut an eyedropper, but that’s as complex as the glasswork gets. Being able to circulate oil with a plastic tube and peristaltic pump is great, too.

If you try it, you need to spring for vacuum pump oil. This type of pump is limited in the vacuum it can draw by the vapor pressure of the fluid in use, and just any oil won’t do. Most have vapor pressures far in excess of anything useful. In the old days, only mercury would cut it, but modern chemistry has come up with very stable oils that will do nearly as well.

How well? [Gabriel] isn’t sure; he bottomed out his gauge at 30 inches of Mercury (102 kPa). It may not be any lower than that, but it’s fair to say the pump draws a healthy vacuum without any unhealthy liquid metals. Enough to brew up some tubes, perhaps.

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A Steady Vacuum For The Fastest Cassette Tape Drive Ever

June 5, 2025 by 39 Comments

If you think of a 1960s mainframe computer, it’s likely that your mental image includes alongside the cabinets with the blinkenlights, a row of reel-to-reel tape drives. These refrigerator-sized units had a superficial resemblance to an audio tape deck, but with the tape hanging down in a loop either side of the head assembly. This loop was held by a vacuum to allow faster random access speeds at the head, and this fascinates [Thorbjörn Jemander]. He’s trying to create a cassette tape drive that can load 64 kilobytes in ten seconds, so he’s starting by replicating the vacuum columns of old.

The video below is the first of a series on this project, and aside from explaining the tape drive’s operation, it’s really an in-depth exploration of centrifugal fan design. He discovers that it’s speed rather than special impeller design that matters, and in particular a closed impeller delivers the required vacuum. We like his home-made manometer in particular.

What he comes up with is a 3D printed contraption with a big 12 volt motor on the back, and a slot for a cassette on the front. It achieves the right pressure, and pulls the tape neatly down into a pair of loops. We’d be curious to know whether a faster motor such as you might find in a drone would deliver more for less drama, but we can see the genesis of a fascinating project here. Definitely a series to watch.

Meanwhile, if your interest extends to those early machine rooms, have a wallow in the past.

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Scrapyard Vacuum Dehydrator Sucks The Water From Hydraulic Oil

February 16, 2025 by 23 Comments

Anyone who has ever had the misfortune of a blown head gasket knows that the old saying “oil and water don’t mix” is only partially true. When what’s coming out of the drain plug looks like a mocha latte, you know you’re about to have a very bad day.

[SpankRanch Garage] recently found himself in such a situation, and the result was this clever vacuum dehydrator, which he used to clean a huge amount of contaminated hydraulic fluid from some heavy equipment. The machine is made from a retired gas cylinder welded to a steel frame with the neck pointing down. He added a fill port to the bottom (now top) of the tank; as an aside, we had no idea the steel on those tanks was so thick. The side of the tank was drilled and threaded for things like pressure and temperature gauges as well as sight glasses to monitor the process and most importantly, a fitting for a vacuum pump. Some valves and a filter were added to the outlet, and a band heater was wrapped around the tank.

To process the contaminated oil, [Spank] glugged a bucket of forbidden milkshake into the chamber and pulled a vacuum. The low pressure lets the relatively gentle heat boil off the water without cooking the oil too badly. It took him a couple of hours to treat a 10-gallon batch, but the results were pretty stark. The treated oil looked far better than the starting material, and while it still may have some water in it, it’s probably just fine for excavator use now. The downside is that the vacuum pump oil gets contaminated with water vapor, but that’s far easier and cheaper to replace that a couple hundred gallons of hydraulic oil.

Never doubt the hacking abilities of farmers. Getting things done with what’s on hand is a big part of farm life, be it building a mower from scrap or tapping the power of the wind.

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Portable Solder Paste Station Prevents Smears With Suction

October 30, 2024 by 30 Comments

Applying solder paste to a new custom PCB is always a little nerve-racking. One slip of the hand, and you have a smeared mess to clean up. To make this task a little easier, [Max Scheffler] built the Stencil Fix Portable, a compact self-contained vacuum table to hold your stencil firmly in place and pop it off cleanly every time.

The Stencil Fix V1 used a shop vac for suction, just like another stencil holder we’ve seen. The vacuum can take up precious space, makes the jig a little tricky to move, and bumping the hose can lead to the dreaded smear and colorful language. To get around this [Max] added a brushless drone motor with a 3D printed impeller, with a LiPo battery for power. The speed controller gets its PWM signal from a little RP2040 dev board connected to a potentiometer. [Max] could have used a servo tester, but he found the motor could be a little too responsive and would move the entire unit due to inertia from the impeller. The RP2040 allowed him to add a low pass filter to eliminate the issue. The adjustable speed also means the suction force can be reduced a little for easy alignment of the stencil before locking it down completely.

We love seeing tool projects like these that make future projects a little easier. Fortunately, [Max] made the designs available so you can build your own.

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On The Nature Of Electricity: Recreating The Early Experiments

October 3, 2024 by No comments

Bits of material levitating against gravity, a stream of water deflected by invisible means, sparks of light appearing out of thin air; with observations like those, it’s a wonder that the early experiments into the nature of electricity progressed beyond the catch-all explanation of magic. And yet they did, but not without a lot of lamb’s bladders and sulfur globes, and not a little hand waving in the process. And urine — lots and lots of urine.

Looking into these early electrical experiments and recreating them is the unlikely space [Sam Gallagher] has staked out with the “Experimental History of Electricity,” a growing playlist on his criminally undersubscribed YouTube channel. The video linked below is his latest, describing the apparatus one Francis Hauksbee used to generate static electric charges for his early 18th-century experiments. Hauksbee’s name is nowhere near as well-known as that of Otto von Guericke or William Gilbert, who in the two centuries before Hauksbee conducted their own experiments and who both make appearances in the series. But Hauksbee’s machine, a rotating glass globe charged by the lightest touch of a leather pad, which [Sam] does a fantastic job recreating as closely as possible using period-correct materials and methods, allowed him to explore the nature of electricity in much greater depth than his predecessors.

But what about the urine? As with many of the experiments at the time, alchemists used what they had to create the reagents they needed, and it turned out that urine was a dandy source of phosphorous, which gave off a brilliant light when sufficiently heated. The faint light given off by mercury when shaken in the vacuum within a barometer seemed similar enough that it became known as the “mercurial phosphor” that likely inspired Hauksbee’s electrical experiments, which when coupled with a vacuum apparatus nearly led to the invention of the mercury discharge lamp, nearly 200 years early. The more you know. Continue reading “On The Nature Of Electricity: Recreating The Early Experiments” →