A Call For Better Shower Temperature Controls

February 18, 2023 by 144 Comments

A good shower is a beautiful, rejuvenating experience. Contrarily, a shower that’s either too hot or too cold becomes a harrowing trial of endurance. [Ben Holmen] has been musing on the way we control temperature in our showers, and he has come to the conclusion that it’s not good enough. He’s done the math, quantified the problem, and is calling for better solutions for all.

[Ben]’s plot of shower temperature vs. mixer tap angle.
[Ben]’s complaint rests with the mixer taps that have become the norm in modern shower installations. These taps have a 180-degree range of motion. On one end, you get maximum cold water output, on the other, maximum hot water output. This is fine for a kitchen sink where we often want one extreme or the other, and exact temperature isn’t important. However, for a shower, it’s terrible.

By [Ben]’s measurements, just a 10-degree range on his own shower tap corresponds to comfortable, usable temperatures. That’s means just 5.6% of the control range is devoted to temperatures the user is likely to select. His argument goes that this is the opposite of how it should work, and that most of the tap’s range should be dedicated to comfortable temperatures.

Ideal water temperature curve, compared to standard tap.

This would allow much finer control of shower temperature in the actual useful range. It would allow us to make tweaks to our shower temperature without having to ever-so-delicately nudge the mixer tap. Extreme hot and extreme cold temperatures should still be available, but left at the utter extremes.

Sadly, [Ben] doesn’t work for Big Tap, so he can’t directly influence the product sold to the public. Instead, he’s calling for manufacturers to develop shower valves that prioritize the temperatures that humans desire most. Unfortunately, it’s not immediately clear how the mechanics of such a valve would work without adding considerable cost and complexity when compared to the traditional model.

What do you think? Are things fine the way they are, or does [Ben] have a point? Perhaps you’re a two-tap evangelist! In any case, we’d love to hear your comments below. Meanwhile, if you’re more worried about the water bill than the temperature, we can help you there as well!

Two goniometers sit on a table. One is an open wooden box with a long piece of plywood along the bottom. A laser distance finder rests on the front edge and a printed angle scale has been attached to the back side of the box. To the right of this box is a much smaller goniometer made from an orange pipe cap with a small strip of paper serving as the angle scale inside the interior edge. It is attached to a wooden handle that looks vaguely like a V. A laser pointer can be inserted from the bottom where a hole has been drilled through the wood.

Goniometer Gives You An Edge At Knife Sharpening

February 9, 2023 by 11 Comments

Sometimes you absolutely, positively need to know the angle of the cutting edge on a knife. When you do, the best tool for the job is a laser goniometer, and [Felix Immler] shows us three different ways to build one. (YouTube)

The underlying principle of all three of these builds is to project reflected laser light off a knife blade onto a scale going from 0-45˚. [Immler] shows a basic demonstration of this concept with a hinge toward the beginning of the video (after the break). Blades with multiple bevels will reflect light to each of the appropriate points on the scale.

The simplest version of the tool is a printed PDF scale attached to a wooden box with a hole for the blade to pass through. The next uses a large pipe end cap and a drilled-out piece of wood to create a more manageable measuring tool. Finally, [Immler] worked with a friend to design a 3D printed goniometer with differently-sized adapters to fit a variety of laser pointers.

Now that you’re ready to precisely sharpen your blades, why not sharpen this guacamole bot or try making your own knife from raw ore?

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Five Years On, Where Is Starman And Where Will He Go?

February 9, 2023 by 55 Comments

On 6 February 2018, a Tesla Roadster was launched as the mass simulator on the first ever Falcon Heavy launch — putting for the first time ever a car on a Mars-crossing orbit. While undoubtedly a bit of a stunt, the onboard cameras provided an amazing view of our planet Earth as the Starman dummy in the Roadster slowly drifted away from that blue marble, presumably never to be seen again.

This “never” is the point that researchers at the University of Toronto would like to clarify in a paper published after the launch titled The Random Walk of Cars and Their Collision Probabilities with Planets. Using N-body simulations, they come to the conclusion that there’s a 22%, 12%, and 12% chance of the Roadster impacting the Earth, Venus, and the Sun, respectively. But don’t get too excited, it’s not due to happen for a few million years, so it isn’t something any of us will be around to see.

As the Where Is Starman? website shows, the Roadster never reached escape velocity from the Sun’s gravity, meaning that it’s still zipping around in an orbit around our day star. Exposed to the harsh UV and other radiation, it’s likely that very little is left at this point of the Tesla, or Starman himself. Even so, scientists to this day are feeling less than amused by what they see as essentially littering, adding to the discarded rocket stages, dead satellites and other debris that occasionally makes it into the news when it smashes into the Moon, or threatens the ISS.

Experimenting With 20 Meters Of Outlet Adapters

February 4, 2023 by 100 Comments

You may have seen some of the EEVblog dumpster dive videos, where [Dave Jones] occasionally finds perfectly good equipment that’s been tossed out. But this time, rather than a large screen monitor, desktop computer, or a photocopier, he features a stash of 283 electrical outlet double adapters that he found last year. He decided to perform a test in the parking lot, connecting all 283 adapters in series.

Using a pair of power meters and a 2 kW electric heater as a test load, [Dave] and his son [Sagan] measure the loss through this wild setup. It works out to about about 300 W, or roughly 1 W per adapter. He did a follow-up experiment using a FLIR thermal camera, and confirmed that the power loss is reasonably uniform, and that no single rogue adapter consuming all the lost power. After a back of the envelope calculation, we estimate this chain of adapters is about 20 meters long, making this whole thing entirely pointless but interesting nonetheless. Stick around until the end of the video for a teardown — they’re not as cheaply made as you might think.

[Dave]’s crazy experiment aside, we do wonder why someone had so many adapters to throw away in the first place. What would you have done with 283 adapters — left them in the dumpster or rescued them?

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Hackaday Links: January 29, 2023

January 29, 2023 by 22 Comments

We’ve been told for ages that “the robots are coming for our jobs!” It’s true that we’ve seen robots capable of everything from burger flipping to bricklaying being demonstrated, and that’s certainly alarming for anyone employed in such trades. But now it looks like AI has set its sights set on the white-collar world, with the announcement that ChatGPT has managed a passing grade on a Wharton MBA exam.

For those not in the know, the University of Pennsylvania’s Wharton School of Business is in the major league of business schools; earning a Master’s in Business Administration from that august institution is no mean feat, and is likely to put the budding executive on a ballistic career trajectory. So the fact that ChatGPT could pass the exam is significant. But before you worry about a world in which our best and brightest business leaders are replaced with soulless automatons, relax. The exam presented to ChatGPT was just a final exam for one course, Operations Management, so it’s not like it aced everything an MBA is expected to know, and it took a lot of hints from a human helper to get it that far. It’s also reported that it made a lot of simple math mistakes, too, so maybe a Wharton MBA isn’t that much of a big deal after all.

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LED Air Vent Gauges Are A Tasteful Mod For The Mazda Miata

January 27, 2023 by 23 Comments

Anyone in the JDM scene can tell you, round air vents are prime real estate for round analog gauges. If you want a gauge but don’t want to block your vent, you could consider building these LED vent gauges from [ktanner] instead.

Tasteful, no?

The design is simple. It relies on 3D printing a replacement bezel for the Mazda Miata’s stock round air vents. This bezel is designed to hold a NeoPixel ring from Adafruit. When built with the optional laser-cut diffuser, the parts have a near-stock look when the LEDs are turned off. It’s a classy, stealthy mod – exactly the sort of thing Miata owners need but never seem to have! (Author Note: don’t be mad, I was once one of you!)

With 24 addressable RGB LEDs, it’s possible to display all kinds of data by turning the LEDs on and off and varying the colors. For example, you could readily build a boost gauge that turns on more LEDs at higher boost pressure. It could then be set up to flash red in the event that you surpass safe thresholds. [ktanner] hasn’t specified any particular microcontroller for the setup — but just about any part you like can be used to drive NeoPixels, after all.

If you’re new to NeoPixels, you might find a simulator useful for developing your projects. Meanwhile, if you’re doing similar work on other cars, be sure to hit us up on the tipsline!

Four images in one. Top left is an image of four individuals in a room with whiteboards and desks in the background along with various clutter on the floor. Over the people is a wireframe overlay of their poses. The image on the top right is just the wireframe people on a black background. Bottom left image is of a single individual standing in a room with the pose wireframe overlay. Bottom right image is the single pose wireframe on a black background.

Tracking Humans With WiFi

January 26, 2023 by 46 Comments

In case you thought that cameras, LiDAR, infrared sensors, and the like weren’t enough for Big Brother to track you, researchers from Carnegie Mellon University have found a way to track human movements via WiFi. [PDF via VPNoverview]

The process uses the signals from WiFi routers for an inexpensive way to determine human poses that isn’t hampered by lack of illumination or object occlusion. The system produces UV coordinates of human bodies by analyzing signal strength and phase data to generate a 2D feature map and then feeding that through a modified DensePose-RCNN architecture which corresponds to 3D human poses. The system does have trouble with unusual poses that are not in the training set or if there are more than three subjects in the detection area.

While there are probably applications in Kinect-esque VR Halo games, this will probably go straight into the toolbox of three letter agencies and advertising-fueled tech companies. The authors claim this to use “privacy-preserving algorithms for human sensing,” but only time will tell if they’re correct.

If you’re interested in other creepy surveillance tools, checkout the Heat-Sensing Crotch Monitor or this Dystopian Peep Show.