The jumping off point for this experiment is the calorie count on the back of food packaging. [Ben] touches on “bomb calorimetry” — the process of burning foodstuff in an oxygen-rich environment and measuring the heat given off to establish how much energy was present in the sample. But our bodies are flameless… can we really extract similar amounts of energy as these highly controlled combustion chambers? His solution is to measure his body’s intake by eating nothing but Soylent for a week, then subjects his body’s waste to the bomb calorimetry treatment to calculate how much energy was not absorbed during digestion. (He burned his poop for science, and made fun of some YouTubers at the same time.)
The test apparatus is a cool build — a chunk of pipe with an acrylic/glass laminated window that has a bicycle tire value for pressurization, a pressure gauge, and electrodes to spark the combustion using nichrome wire and cotton string. It’s shown above, burning a Goldfish® cracker but it’s not actually measuring the energy output as this is just a test run. The actual measurements call for the combustion chamber to be submerged in an insulated water bath so that the temperature change can be measured.
Now to the dirty bits. [Ben] collected fecal matter and freeze-dried it to ready it for the calorimeter. His preparation for the experiment included eating nothing but Soylent (a powdered foodstuff) to achieve an input baseline. The problem is that he measures the fecal matter to have about 75% of the calories per gram compared to the Soylent. Thinking on it, that’s not surprising as we know that dung must have a high caloric level — it burns and has been used throughout history as a source of warmth among other things. But the numbers don’t lead to an obvious conclusion and [Ben] doesn’t have the answer on why the measurements came out this way. In the YouTube comments [Bitluni] asks the question that was on our minds: how do you correlate the volume of the input and output? Is comparing 1g of Soylent to 1g of fecal matter a correct equivalency? Let us know what you think the comments below.
Ultrasonic soldering is a little-known technology that allows soldering together a variety of metals and ceramics that would not normally be possible. It requires a special ultrasonic soldering iron and solder that is not cheap or easy to get hold of, so [Ben Krasnow] of [Applied Science] made his own.
Ultrasonic soldering irons heat up like standard irons, but also require an ultrasonic transducer to create bonds to certain surfaces. [Ben] built one by silver soldering a piece of stainless steel rod (as a heat break) between the element of a standard iron and a transducer from an ultrasonic cleaner. He made his special active solder by melting all the ingredients in his vacuum induction furnace. It is similar to lead-free solder, but also contains titanium and small amounts of cerium and gallium. In the video below [Ben] goes into the working details of the technology and does some practical experimentation with various materials.
Ultrasonic soldering is used mainly for electrically bonding metals where clamping is not possible or convenient. The results are also not as neat and clean as with standard solder. We covered another DIY ultrasonic soldering iron before, but it doesn’t look like that one ever did any soldering.
Ultrasonic energy has several interesting mechanical applications that we’ve covered in the past, including ultrasonic cutting and ultrasonic welding.
For most of human history, there was no such thing as a professional scientist. Those who dabbled in “natural philosophy” were mainly men — and occasionally women — of privilege and means, given to spend their time looking into the workings of the world. Most went where their interest lay, exploring this facet of geology or that aspect of astronomy, often combining disciplines or switching to new ones as they felt like it. They had the freedom to explore the universe without the pressure to “publish or perish,” and yet they still often managed to pull back the curtain of ignorance and superstition that veiled the world for eons, at least somewhat.
In their footsteps follow today’s citizen scientists, a relatively small cohort compared to the great numbers of professional scientists that universities churn out year after year. But where these credentialed practitioners are often hyper-focused on a particular sub-field in a highly specialized discipline, the citizen scientist enjoys more freedom to explore the universe, as his or her natural philosopher forebears did. These citizen scientists — many of whom are also traditionally credentialed — are doing important work, and some are even publishing their findings in mainstream journals. Continue reading “Citizen Science Hack Chat With Ben Krasnow”→
Join editors Elliot Williams and Mike Szczys as they unpack all the great hacks we’ve seen this week. On this episode we’re talking about laser Internet delivered from space, unwrapping the complexity of Charlieplexed circuits, and decapping ICs both to learn more about them and to do it safely at home. We have some fun with backyard siege weapons (for learning about physics, we swear!), gambling on FPGAs, and a line-scanning camera that’s making selfies fun again. And nobody thought manufacturing electroluminescent displays was easy, but who knew it was this hard?
Take a look at the links below if you want to follow along, and as always, tell us what you think about this episode in the comments!
The jet of pure water emerges from a 0.004″, or 100 micron, diameter sapphire orifice with a flow rate of around 2 milliliters per second giving a speed of 240 meters per second. It collides at 90° with a dielectric material where the plasma is produced as a toroid surrounding the collision point.
There’s been very little research into the phenomena but a proposal from one research paper which [Ben] found is that the plasma is a result of charging due to the triboelectric effect. This is the same effect which charges a balloon when you rub it against your hair, except that here there are water molecules running across a clear dielectric such as fused quartz. This effect results in a positively charged anode downstream of the collision while the water near the point of highest shear becomes conductive and conducts negative charge to the point of smallest curvature, producing a cathode. The electric field at the small-radius cathode acts like a short point with a high voltage on it, ionizing the air and forming the plasma. If this form of ionization sounds familiar, that’s because we’ve talked it occurring between the sharp wire and rounded foil skirt of a flying lifter.
[Ben] found support for the triboelectric theory when he substituted oil for the water. This didn’t produce any plasma, which is be expected since unlike water, oil is a non-polar molecule. However, while the researchers tried just a few dielectric materials, [Ben] had success with every transparent dielectric which he tried, including fused quartz, lithium niobate, glass, polycarbonate, and acrylic, some of which are very triboelectrically different from each other. So there’s room here for more theorizing. But check out his full video showing his equipment for producing the waterjet as well as his demonstrations and explanation.
After starting out with a demo of the firmware in action before and after his modification, he explains how the E-paper works. The display is made up of many isolated chambers, each containing charged particles in a liquid. For example, the positive particles might be black and the negative might be white. By putting an electric field across each chamber, the white particles would be attracted to one end while the black would be attracted to the other, which could be the end you’re looking at. He also explains how it’s possible to get a third color by using different sized particles along with some extra manipulation of the electric field. And he talks about the issue of burn-in and how to avoid it.
Having given us that background, he then walks us through some of the firmware and shows how he modified it to make it faster, namely by researching various datasheets and subsequently modifying some look-up-tables.
Turning back to the hardware, he shows how he scratches out some traces so that he can attach scope probes. This alone seems like a notable achievement, though he points out that the conductive layer holds up well to his scratching. At that point he analyses the signals while running some demos.
The result is the very informative, interesting and entertaining video which you can watch below.