On the left side, there's a smartphone. On the right side, there's a hairdryer turned on. On the smartphone screen, you can see the working end of the hairdryer shown, as well as a jet of air coming out of that end. In the background, there's an LCD screen showing a noise pattern.

Observe Airflow Using Smartphone And Background-Oriented Schlieren

July 17, 2022 by 22 Comments

Multiple people have recently shared this exciting demonstration (nitter) with us – visualizing airflow using a smartphone, called ‘background-oriented schlieren’. On a hot summer day, you might see waves in the air – caused by air changing density as it warms up, and therefore refracting the light differently. Schlieren photography is an general set of techniques for visualizing fluid flow, but of course, it can also be applied to airflow. In this case, using some clever optical recognition tricks, this schlieren method lets you visualize flow of air using only your Android smartphone’s high resolution camera and a known-pattern printed background! Continue reading “Observe Airflow Using Smartphone And Background-Oriented Schlieren” →

It Turns Out You Can’t Just Fly A Drone Under Water

July 17, 2022 by 27 Comments

The differences between a drone and an underwater remote-operated vehicle (ROV) aren’t actually that large. Both have powerful motors that move large volumes of fluid (yes, air is a fluid), a camera, a remote, and an onboard battery. So when [RCLifeOn] got his hands on a cheap used drone, he reckoned that it could fly underwater just as well as it did in the air.

To his credit, the principle was sound, and the initial tests looked promising. However, we will spoil the ending and tell you it doesn’t work out as well as he hoped due to water leakage. He printed a case with a large panel for accessing electronics inside and an acrylic window for the camera. The panel pressed up against a gasket via the few dozen metric screws along the perimeter. Despite the design being quite whimsical, he quickly regrets the screws as getting inside is tiring on the wrists. He epoxies the hatch to the hull and drills holes to charge the battery to stop the seemingly never-ending water leaks. After its maiden journey, water got inside and fried some of the motor controllers. So for the second test run, he used what limited capabilities it had left.

Despite the project not working out how he expected, it’s a great example of how some reused parts and some 3d printing can make something entirely different. So perhaps next time, instead of throwing that broken drone away, see if it could be given just a bit of love. Possibly the propellers can be combined or make do with only three motors. Or just go the [RCLifeOn] route and make it into something new entirely.

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Beautiful Inductors, Now Not Such A Lost Art

July 17, 2022 by 12 Comments

As ferrite technology has progressed into a mastery of magnetic permeability, the size of inductors has gone down to the point at which they are now fairly nondescript components. There was a time though when inductors could be beautiful creations of interleaving layers of copper wire in large air-cored inductors, achieved through clever winding techniques. It’s something that’s attracted the attention of [Brett], who’s produced a machine capable of producing something close to the originals.

Part of the write-up is an investigation of the history, these coils were once present even at the consumer level but are now the preserve of only a few highly secretive companies. They are still worth pursuing though because they can deliver the high “Q” factor that is demanded in a high quality tuned circuit. The rest of the write-up dives in detail into the design of the wire feeder, and the Arduino motor control of the project. There should be enough there for any other experimenters to try their hands at layered inductors, so perhaps we’ll see this lost art make a comeback.

Custom coils are a regular requirement for anything from radios, to musical instruments, to switching power supplies, so it’s not surprising that quite a few projects featuring them have made it here. One of the more unusual of late has been one that winds toroids.

A Home Made Sewing Machine May Be The Only One

July 17, 2022 by 36 Comments

The sewing machine is a tool that many of us will have somewhere around our workshop. Concealed within it lies an intricate and fascinating mechanism. Some of us may have peered inside, but very few indeed of us will have gone to the effort of building our own. In case you had ever wondered whether it was possible, [Fraens] has done just that, with what he claims may be the only entirely homemade sewing machine on the Internet.

If you’ve ever studied the history of sewing machines you’ll notice that it bears a striking resemblance to some of the earliest commercial machines, with a relatively short reach and an entirely open construction. The main chassis appears to be laser-cut acrylic while all the fittings are 3D-printed, with machined brass bushes and aluminum rods for the other metal parts. The design utilizes a hand crank, but is also pictured with a DC motor. It makes for a fascinating illustration of how sewing machines work. Sadly we can’t see any design file links (Update: He’s contacted us to tell us they’re now on Thingiverse.), so you might have to be inventive if that’s the way you want to build your own. Take a look at it in the video below the break.

Fancy a sewing machine but don’t fancy making your own? We’ve got the guide for that, and for filling the rest of your textile bench.

Continue reading “A Home Made Sewing Machine May Be The Only One” →

A No-Calibration Metal Detector

July 17, 2022 by 12 Comments

A traditional early project for someone discovering a love for electronics has been for many years a metal detector. This would mean a few transistors back in the day, but today it’s more likely to involve a microcontroller. [Mircemk] has an example that bends both worlds, with a single transistor oscillator and an Arduino.

This type of metal detector has a large search coil which forms part of the tuned circuit in an oscillator. As a piece of metal enters its range the frequency of oscillation changes. In the old days, this would have been detected as an audible beat frequency with another oscillator. This design would require a calibration step at the start of detecting, to tune the two oscillators to the same frequency.

This detector keeps the first oscillator but eschews the second one in favor of an Arduino. The microcontroller acts as a frequency counter, monitoring the frequency and issuing an alarm when it detects a change likely to be caused by a piece of metal. It may not have some of the finess a human ear could apply to a beat frequency in the all-analogue days, but it’s simple enough to build and it avoids the need for calibration. Seeing it in the video below the break we’re sure that just like those transistor models old, there will be plenty of fun to be had with it.

An Arduino may be one of the current go-to parts, but will it ever displace the 555? Perhaps not in the world of metal detectors!

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strut mounted on lathe

Turning Irregular Shapes

July 16, 2022 by 33 Comments

In case you’re not closely following Egyptian Machinist YouTube, you may have missed [Hydraulic House]. It’s gotten even harder to find him since he started posting under[بيت الهيدروليك]. Don’t let the Arabic put you off, he delivers it all in pantomime.

A recent drop is “How To Turn Irregular Shapes On The Lathe“.  We’re not sure, but think the part he’s working on is the front suspension of a  3 wheeled auto-rickshaw. The first metal at the center is over 30cm from the bottom. No problem, he just makes a long driven dead center from a bit of scrap material and goes on with his business.

By no means is this the only cool video.  We liked his video on a remote pumped hydraulic jack  and one on making your own hydraulic valves.

If you’re into machinist-y things, don’t miss him. Every video is full of pretty nifty tricks, sometimes made with a zany disregard of some basics like “maybe better to have done the welding before mounting in the lathe”, turning with a cutoff tool (I think), and occasionally letting go of the chuck key. It’s definitely ‘oh, get on with it’ machine shop work.

We love videos from professionals in the developing world making with relatively simple tools. Often hobby hackers are in the same position, milling with a lathe and some patience instead of a giant Okuma. Not long ago we posted this article about making helical parts , with the same ‘imagination and skill beats more machinery any day’ vibe.

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Insect class-order-family-genus-species chart with drawn examples

Neural Network Identifies Insects, Outperforming Humans

July 16, 2022 by 15 Comments

There are about one million known species of insects – more than for any other group of living organisms. If you need to determine which species an insect belongs to, things get complicated quick. In fact, for distinguishing between certain kinds of species, you might need a well-trained expert in that species, and experts’ time is often better spent on something else. This is where CNNs (convolutional neural networks) come in nowadays, and this paper describes a CNN doing just as well if not better than human experts.

Continue reading “Neural Network Identifies Insects, Outperforming Humans” →