A Modern Solution To Tea Bag Inventory Management

Britain is famously known as a land of manners and hospitality. Few situations could make an Englishman’s stiff upper lip quiver, short of running out of tea bags while entertaining house guests. Thankfully, [The Gentleman Maker] is here and living up to his name – with a helpful tea monitor to ensure you’re never caught out again.

The Intelli-T, as it has been dubbed, monitors tea inventory by weight. An Arduino Uno combined with a HX711 IC monitors a load cell mounted under a canister, with a reed switch on the lid. Upon the canister being open and closed, the Arduino takes a measurement, determining whether tea stocks have dipped below critical levels. If the situation is dire, a Raspberry Pi connected over the serial port will sound an urgent warning to the occupants of the home. If there is adequate tea, the Raspberry Pi will instead provide a helpful tea fact to further educate the users about the hallowed beverage.

It’s a fun project, and one that has scope for further features, given the power of the Raspberry Pi. A little more work could arrange automatic ordering of more tea online, or send alerts through a service like IFTTT. We’ve seen [The Gentleman Maker]’s uniquely British hacks before, such as the umbrella that tells you the weather. Video after the break.

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Don’t Need A Weatherman To Know Which Way The Wind Blows On Mars

NASA’s latest Mars lander has a very precise weather package, and you can check the daily conditions on Elysium Planitia online. The data however has apparently led to a bit of a mystery. According to Ars Technica, every day at 7AM and 7PM local time, there’s an unexplained atmospheric pressure spike.

The TWINS (Temperature and Wind for InSight) package provided by Spain’s Centro de Astrobiología shows the little spikes regularly since the lander hit the ground in November. They seem to correspond to local sunrise and sunset. Keep in mind, the pressure on Mars is very low — about 1% of Earth’s atmosphere — and scientists have already ruled out instrument problems.

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OptoGlitch Is An Optocoupler Built For Distortion

When we are concerned with the accurate reproduction of a signal, distortion and noise are the enemy that engineers spend a great deal of time eliminating wherever possible. However, humans being the imperfect creatures that we are, we sometimes desire a little waviness and grain in our media – typically of the analog variety, as the step changes of digital distortion can be quite painful. Tired of Instagram filters and wanting to take a different approach, [Patrick Pedersen] built the OptoGlitch – a hardware solution for analog distortion.

Changing the number of samples per pixel varies the accuracy of reproduction of the original image, left.

The concept of operation is simple – pixel values of a digital image are sent out by varying the intensity of an LED, and are then picked up by a photoresistor and redigitized. The redigitized image then bears a variety of distortion and noise effects due to the imperfect transmission process.

In the OptoGlitch hardware, the LED and photoresistor are intentionally left open to ambient light to further allow noise and distortion to happen during the transmission process. A variety of calibration methods are used to avoid the results being completely unrecognizable, and there are various timing and sampling parameters that can be used to alter the strength of the final effect.

It’s possible to introduce distortion more intentionally, too – such as this project that hides metadata in malformed glyphs.

DIY X-Ray Machine Becomes CT Scanner

Once you’ve built your own X-ray machine to take 2D images of the insides of stuff, there’s really only one logical next step: building your own computed tomography (CT) scanner to get 3D reconstructions instead. That’s exactly what [Fran Piernas] has done, and documented over on hackaday.io. While the original X-ray machine build dealt with scary hardware stuff such as high voltage and ionizing radiation, this time it’s the turn of scary mathematics like inverse radon transforms.

The original build, which we wrote about in December, uses a commercial dental X-ray tube and a home-made 65 kV power supply to send X-rays through objects. Transmitted X-rays are viewed using an intensifying screen that converts the rays to visible light. The result is a 2D image similar to that we’re all familiar with.

To create a 3D reconstruction of an object, you need a number of X-ray images taken from different angles. If you’ve ever been unlucky enough to need a medical CT scan, you’ll remember staying motionless in the tunnel while the X-ray apparatus rotated around you. In this build, [Fran] rotates the object instead, using a motor that may have once been part of a microwave oven (one of those “mystery motors” we all have laying around). The required sequence of images is simply obtained by recording video of the X-ray screen while the motor rotates the object.

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Retrotechtacular: How Not to Design With Transistors

Consider the plight of a mid-career or even freshly minted electrical engineer in 1960. He or she was perched precariously between two worlds – the proven, practical, and well-supported world of vacuum tube electronics, and the exciting, new but as yet unproven world of the transistor. The solid-state devices had only started making inroads into electronic products relatively recently, and mass production techniques were starting to drive the cost per unit down enough to start including them in your designs. But, your company has a long history with hot glass and no experience with flecks of silicon. What to do?

To answer that question, you might have turned to this helpful guide, “Tubes and Transistors: A Comparative Guide” (PDF link). The fancy booklet, with a great graphic design that our own [Joe Kim] would absolutely love, was the product of the Electron Tube Information Council, an apparently defunct group representing the interests of the vacuum tube manufacturers. Just reading the introduction of this propaganda piece reveals just how worried companies like RCA, General Electric, and Westinghouse must have been as the 1950s turned into the 1960s. The booklet was clearly aimed directly at engineers and sought to persuade them of the vacuum tube’s continued relevance and long-term viability. They helpfully explain that tubes are a reliable, proven technology that had powered decades of designs, and that innovations such as heaterless cathodes and miniaturization were just around the corner. Transistors, we’re told, suffer from “spread of characteristics” that correctly describes the state of materials engineering of silicon and germanium at the time, a thornier problem than dealing with glass and wires but that they had to know would be solved within a few years.

With cherry-picked facts and figures, the booklet makes what was probably in 1960 a persuasive case for sticking with tubes. But the Electron Tube Information Council was fighting a losing battle, and within a decade of swamping engineers with this book, the industry had largely shifted to the transistor. Careers were disrupted, jobs disappeared, and fortunes were lost, but the industry pressed forward as it always does. Still, it’s understandable why they tried so hard to stem the tide with a book like this. The whole PDF is worth a look, and we’d love to have a hard copy just for nostalgia’s sake.

Thanks to [David Gustafik] for the tip.

Badge.Team: Badges Get A Platform

Electronic conference badges are now an accepted part of the lifeblood of our community, with even the simplest of events now sporting a fully functional computer as an eye-catching PCB on a lanyard. Event schedules and applications are shipped on them, and the more sophisticated ones have app libraries and support development communities of their own.

The trouble is that so often those badges fail to live up to their promise, and one reason behind that stems from the enormity of the task facing a badge team when it comes to firmware for a modern badge. There is some fascinating news from the Netherlands  that might reduce some of those firmware woes though, badge.team is a freshly-launched project that provides a ready-made badge firmware with the promise of both stability and long-term support. If you’re making a badge, or even a one-off device using the ESP32, this is a project worth checking out.

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Love Inspires CD Player Hack

The heart is an impressive piece of hardware. It’s a rare pump that runs continuously for over 80 years in some cases. It’s also, for some reason or other, become a common human symbol of love and affection. In this vein, [Deepak Khatri] has built a beating electronic heart out of basic, readily available components.

The heart of the build (pun intended) is a lens assembly salvaged from a CD player, which uses a coil and permanent magnet to move the lens in order to read across a disc. In this case, the coil is instead fed pulses from an astable multivibrator circuit built with a hacker favourite, the 555 timer IC. It’s all assembled on a breadboard, which is a great way to build such projects that rely on experimentation through the swapping of component values.

The end result is rather satisfying. [Deepak] has also experimented with an Arduino driven version with a slightly different rhythm.

We haven’t seen too many projects using optical drive lens assemblies, but we’re sure there must be other applications. If you end up using one to agitate biological samples or build an awesome laser projector, be sure to hit up the tips line. Video after the break.

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