Put A Smoke Detector To Some Use

While we’re certainly not denying that smoke detectors are useful, there’s a certain kind of tragedy to the fact that most of them will never realize their true purpose of detecting smoke, and alerting us to a dangerous fire. On the other hand, [Ben] really unlocks the potential hidden deep in every smoke detector with his latest project which uses the smoke-detecting parts of a smoke detector to turn on the exhaust fan over his stove.

The project didn’t start with the noble aim of realizing the hidden and underutilized quiescent nature of a smoke alarm, though. He wanted his range exhaust fan to turn on automatically when it was needed during his (and his family’s) cooking activities. The particular range has four speeds so he wired up four relays to each of the switches in the range and programmed a Particle Photon to turn them on based on readings from an MQ-2 gas-detecting sensor.

The sensor didn’t work as well as he had hoped. It was overly sensitive to some gasses like LPG which would turn the range on full blast any time he used his cooking spray. Meanwhile, it would drift and not work properly during normal cooking. He tried disabling it and using only a temperature sensor, which didn’t work well either. Finally, he got the idea to tear apart a smoke detector and use its sensor’s analog output to inform the microcontroller of the current need for an exhaust fan. Now that that’s done, [Ben] might want to add some additional safety features to his stovetop too.

My Oscilloscope Uses Fire

If you want to visualize sound waves, you reach for your oscilloscope, right? That wasn’t an option in 1905 so physicist [Heinrich Rubens] came up with another way involving flames. [Luke Guigliano] and [Will Peterson] built one of these tubes — known as a Rubens’ tube — and will show you how you can, too. You can see a video of their results, below. Just in case a flame oscilloscope isn’t enough to attract your interest, they are driving the thing with a theremin for extra nerd points.

The guys show a short flame run and one with tall flames. The results are surprising, especially with the short flames. Of course, the time base is the length of the tube, so that limits your measurements. The tube has many gas jets along the length and with a sound source, the height of the flames correspond to the air pressure from the sound inside the tube.

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Detect Elevated Carbon Monoxide (Levels)

The molar mass of carbon monoxide (CO) is 28.0, and the molar mass of air is 28.8, so CO will rise in an ambient atmosphere. It makes sense to detect it farther from the ground, but getting a tall ladder is not convenient and certainly doesn’t make for fast deployment. What do you do if you don’t care for heights and want to know the CO levels in a gymnasium or a tall foyer? Here to save the day, is the Red Balloon Carbon Monoxide Detector.

Circuit.io generates the diagram and code to operate the CO sensor and turn a healthy green light to a warning red if unsafe levels are detected. The user holds the batteries, Arduino, and light while a red balloon lifts the sensor up to fifteen feet, or approximately five three meters. It is an analog sensor which needs some time to warm up so it pays to be warned about that wire length and startup.

Having a CO sentinel is a wise choice for this odorless gas.

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Building A Gasometer To Store Wood Gas And Other Bio-Fuels

Old solutions are often so elegant and effective that they keep coming back. The gasometer, or gas holder, is one such example. Now [NightHawkInLight] has built one for storing the wood gas he’s been experimenting with, and it’s pretty neat to watch it rise and fall as he first adds gas and then burns it off. The mechanism couldn’t be simpler.

How a gasometer works

For those who, like us, are hearing about this low tech for the first time, gasometers are a means of safely storing gas stemming from the 1700s when gas was king and electricity was little more than a gentleman scientist’s pursuit. In its simplest form, it consists of a container of water with another container filled with gas sitting upside down in the water. Gas pressure is controlled by the weight of the gas-filled container and the water provides a seal, preventing the gas from escaping. Adding gas simply raises the gas-filled container, and removing or using gas lowers it. Simple, safe, and elegant.

We’ll leave the details of how he made his gasometer to the video below, but suffice it to say that his use of a double-walled gas pipe originally intended as a furnace chimney just adds more elegance to this whole hack.

[NightHawkInLight’s] cool projects have graced the pages of Hackaday before. For example, in the area of gas alone there’s his propane-powered plasma rifle, his transparent hybrid rocket engine, and his thermic lance which was hot enough to melt rocks.

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Micro Chainsaw Gets A Much Needed Nitro Power Boost

When life hands you the world’s smallest chainsaw, what’s there to do except make it even more ridiculous? That’s what [JohnnyQ90] did when he heavily modified a mini-electric chainsaw with a powerful RC car engine.

The saw in question, a Bosch EasyCut with “Nanoblade technology,” can only be defined as a chainsaw in the loosest of senses. It’s a cordless tool intended for light pruning and the like, and desperately in need of the [Tim the Toolman Taylor] treatment. The transmogrification began with a teardown of the drivetrain and addition of a custom centrifugal clutch for the 1.44-cc nitro RC car engine. The engine needed a custom base to mount it inside the case, and the original PCB made the perfect template. The original case lost a lot of weight to the bandsaw and Dremel, a cooling fan was 3D-printed, and a fascinatingly complex throttle linkage tied everything together. With a fuel tank hiding in the new 3D-printed handle, the whole thing looks like it was always supposed to have this engine. The third video below shows it in action; unfortunately, with the engine rotating the wrong direction and no room for an idler gear, [JohnnyQ90] had to settle for flipping the bar upside down to get it to cut. But with some hacks it’s the journey that interests us more than the destination.

This isn’t [JohnnyQ90]’s first nitro rodeo — he’s done nitro conversions on a cordless drill and a Dremel before. You should also check out his micro Tesla turbine, too, especially if you appreciate fine machining.

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Knowing What’s Below: Buried Utility Location

We humans have put an awful lot of effort into our infrastructure for the last few centuries, and even more effort into burying most of it. And with good reason — not only are above ground cables and pipes unsightly, they’re also vulnerable to damage from exposure to the elements. Some utilities, like natural gas and sanitary sewer lines, are also dangerous, or at least perceived to be so, and so end up buried. Out of sight, out of mind.

But humans love to dig, too, and it seems like no sooner is a paving project completed than some joker with a jackhammer is out there wrecking the pristine roadway. Before the construction starts, though, cryptic markings will appear on the pavement courtesy of your local buried utility locating service, who apply their rainbow markings to the ground so that nothing bad happens to the often fragile infrastructure below our feet.

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Hackaday Prize Entry: SafeRanger, A Roving Power Plant Monitor

Engineering student [Varun Suresh] designed his SafeRanger rover to inspect oil and gas power plants for abnormal temperatures as well as gas leaks. The rover explores critical areas of the factory, and data is sent to a control center for analysis.

[Varun] built his robot around a Devastator chassis kit from DFRobot, and equipped it with a FLIR Lepton thermal camera and an MQ2 gas sensor, both monitored by a Raspberry Pi. The twin brushless DC motors are controlled by an L293D motor driver IC in conjunction with an Arduino Nano; steering is accomplished with an HC-05 Bluetooth module and a mobile app.

We could see technology like this being implemented in a labyrinthine facility where a human inspector might have a difficult time reaching every nook and cranny. Or just let it wander ar0und, looking for trouble?