Pour Yourself A Glass Of 100,000 Volts

August 5, 2020 by Tom Nardi 15 Comments

You’d be hard pressed to find a hacker or maker who doesn’t have a soft spot for the tantalizing buzz and snap of a high voltage spark gap, but it remains the sort of project that most of us don’t take on personally. There’s a perceived complexity in building a device capable of shooting a proper spark through several inches of open air, with connotations of exotic components and massive hand-wound coils. Plus, nobody wants to inadvertently singe off their eyebrows.

While the latest video from [Jay Bowles] might not assuage anyone’s fear of performing impromptu electrolysis, it does at least prove that you don’t need to have a laboratory full of gear to produce six figure voltages. In fact, you don’t even need much in the way of electronics: the key components of this DIY Marx generator are made with little more than water and some household items.

This is made possible by the fact that the conductivity of water can be changed depending on what’s been dissolved into it. Straight tap water is a poor enough conductor that tubes of it can be used in place of high voltage resistors, while the addition of some salt and a plastic insulating layer makes for a rudimentary capacitor. You’ll still need wires to connect everything together and some bits of metal to serve as spark gaps, but nothing you won’t find lurking in the parts bin.

Of course, water and a smattering of nails won’t spontaneously generate electricity. You need to give it a bit of a kick start, and for that [Jay] is using a 15,000 volt DC flyback power supply that looks like it may have been built with components salvaged from an old CRT television. While the flyback transformer alone could certainly generate some impressive sparks, this largely liquid Marx generator multiplies the input voltage to produce a serious light show.

We’re always glad to see a new video from the perennially jovial [Jay] come our way. While his projects might not always be practical in the strictest sense, they never fail to inspire a lively discussion about the fascinating applications of high voltage.

Continue reading “Pour Yourself A Glass Of 100,000 Volts” →

See The Science Behind VR Display Design, And What Makes A Problem Important

August 3, 2020 by Donald Papp 28 Comments

VR headsets are more and more common, but they aren’t perfect devices. That meant [Douglas Lanman] had a choice of problems to address when he joined Facebook Reality Labs several years ago. Right from the start, he perceived an issue no one seemed to be working on: the fact that the closer an object in VR is to one’s face, the less “real” it seems. There are several reasons for this, but the general way it presents is that the closer a virtual object is to the viewer, the more blurred and out of focus it appears to be. [Douglas] talks all about it and related issues in a great presentation from earlier this year (YouTube video) at the Electronic Imaging Symposium that sums up the state of the art for VR display technology while giving a peek at the kind of hard scientific work that goes into identifying and solving new problems.

[Douglas] chose to address seemingly-minor aspects of how the human eye and brain perceive objects and infer depth, and did so for two reasons: one was that no good solutions existed for it, and the other was that it was important because these cues play a large role in close-range VR interactions. Things within touching or throwing distance are a sweet spot for interactive VR content, and the state of the art wasn’t really delivering what human eyes and brain were expecting to see. This led to years of work on designing and testing varifocal and multi-focal displays which, among other things, were capable of presenting images in a variety of realistic focal planes instead of a single flat one. Not only that, but since the human eye expects things that are not in the correct focal plane to appear blurred (which is itself a depth cue), simulating that accurately was part of things, too.

The entire talk is packed full of interesting details and prototypes. If you have any interest in VR imaging and headset design and have a spare hour, watch it in the video embedded below.

Continue reading “See The Science Behind VR Display Design, And What Makes A Problem Important” →

Electrochemistry At Home

August 2, 2020 by Orlando Hoilett 11 Comments

A few years ago, I needed a teeny, tiny potentiostat for my biosensor research. I found a ton of cool example projects on Hackaday and on HardwareX, but they didn’t quite fulfill exactly what I needed. As any of you would do in this type of situation, I decided to build my own device.

Now, we’ve talked about potentiostats before. These are the same devices used in commercial glucometers, so they are widely applicable to a number of biosensing applications. In my internet perusing, I stumbled upon a cool chip from Texas Instruments called the LMP91000 that initially appeared to do all the hard work for me. Unfortunately, there were a few features of the LMP91000 that were a bit limiting and didn’t quite give me the range of flexibility I required for my research. You see, electrochemistry works by biasing a set of electrodes at a given potential and subsequently driving a chemical reaction. The electron transfer is measured by the sensing electrode and converted to a voltage using a transimpedance amplifier (TIA). Commercial potentiostats can have voltage bias generators with microVolt resolution, but I only needed about ~1 mV or so. The problem was, the LMP91000 has a resolution of ~66 mV on a 3.3 V supply, mandating that I augment the LMP991000 with an external digital-to-analog converter (DAC) as others had done.

However, changing the internal reference of the LMP91000 with the DAC confounded the voltage measurements from the TIA, since the TIA is also referenced to the same internal zero as the voltage bias generator. This seemed like a problem other DIY solutions I came across should have mentioned, but I didn’t quite find any other papers describing this problem. After punching myself a little, I thought that maybe it was a bit more obvious to everyone else except me. It can be like that sometimes. Oh well, it was a somewhat easy fix that ended up making my little potentiostat even more capable than I had originally imagined.

I could have made a complete custom potentiostat circuit like a few other examples I stumbled upon, but the integrated aspect of the LMP91000 was a bit too much to pass up. My design needed to be as small as possible since I would eventually like to integrate the device into a wearable. I was using a SAMD21 microcontroller with a built-in DAC, therefore remedying the problem was a bit more convenient than I originally thought since I didn’t need an additional chip in my design.

I am definitely pretty happy with the results. My potentiostat, called KickStat, is about the size of a US quarter dollar with a ton of empty space that could be easily trimmed on my next board revision. I imagine this could be used as a subsystem in any number of larger designs like a glucometer, cellphone, or maybe even a smartwatch.

Check out all the open-source files on my research lab’s GitHub page. I hope my experience will be of assistance to the hacker community. Definitely a fun build and I hope you all get as much kick out of it as I did.

Enjoying Some Exothermic Welding, With Thermite!

July 30, 2020 by Maya Posch 21 Comments

There probably aren’t many people out there who aren’t aware of what thermite is and how it demonstrates the power of runaway exothermic reactions. Practical applications that don’t involve destroying something are maybe less known. This is where the use of thermite for creating welds is rather interesting, as shown in this video by [Finn] that is also embedded after the break.

In the video, one can see how [Finn] uses thermite charges to weld massive copper conductors together in a matter of seconds inside a graphite mold. Straight joints, T-joints, and others are a matter of putting the conductors into the mold, pushing a button and watching the fireworks. After a bit of cleaning the slag off, a solid, durable weld is left behind.

The official name for this process is ‘exothermic welding‘, and it has been in use since the 19th century. Back then it was used primarily for rail welding. These days it sees a lot of use in high-voltage wiring and other applications, as in the linked video. The obvious advantage of exothermic welding is that the resulting joint is strong and durable, on account of the two surfaces having been permanently joined.

Continue reading “Enjoying Some Exothermic Welding, With Thermite!” →

An Open-Source Microfluidic Pump For Your Science Needs

July 29, 2020 by Lewin Day 8 Comments

When it comes to research in fields such as chemistry or biology, historically these are things that have taken place in well-financed labs in commercial settings or academic institutions. However, with the wealth of technology available to the average person today, a movement has sprung up of those that run advanced experiments in the comfort of their own home laboratory. For those needing to work with very tiny amounts of liquid, [Josh’s] microfluidics pump may be just the ticket.

Consisting of a series of stepper-motor driven pumps, the hardware is inspired by modern 3D printer designs. The motors used are all common NEMA items, and the whole system is driven by the popular Marlin firmware. The reported performance is impressive, delivering up to 15 mL/min with accuracy to 0.1uL/min. That’s a truly tiny amount of fluid, and the device could prove highly useful to those exploring genetics or biology at home.

The great thing about this build is that it’s open source. [Josh] took the time to ensure that it was easily moddable to work with different tubing and materials, such that others could spin up a copy using whatever was readily available in their area. Performance will naturally vary, but if you’re experienced enough to build a microfluidic pump, you’re experienced enough to calibrate it, too. Design files are on Github for those keen to build their own.

We’ve seen other builds in this area before, too. We look forward to seeing some fun science done with [Josh]’s build, and look forward to seeing more DIY science gear in the future!

Smashing The Atom: A Brief History Of Particle Accelerators

July 29, 2020 by Moritz v. Sivers 28 Comments

When it comes to building particle accelerators the credo has always been “bigger, badder, better”. While the Large Hadron Collider (LHC) with its 27 km circumference and €7.5 billion budget is still the largest and most expensive scientific instrument ever built, it’s physics program is slowly coming to an end. In 2027, it will receive the last major upgrade, dubbed the High-Luminosity LHC, which is expected to complete operations in 2038. This may seem like a long time ahead but the scientific community is already thinking about what comes next.
Recently, CERN released an update of the future European strategy for particle physics which includes the feasibility study for a 100 km large Future Circular Collider (FCC). Let’s take a short break and look back into the history of “atom smashers” and the scientific progress they brought along. Continue reading “Smashing The Atom: A Brief History Of Particle Accelerators” →

Ultracapacitors Might Have Bad Fruity Smell

July 29, 2020 by Al Williams 21 Comments

You might think the smell of an electrolytic capacitor boiling out is bad, but if scientists from the University of Sydney have their way, that might be nothing. They’ve devised an ultracapacitor — that uses biomass from the stinky durian fruit along with jackfruit. We assume the capacitors don’t stink in normal use, but we wouldn’t want to overload one and let the smoke out.

One of the things we found interesting about this is that the process seemed like something you might be able to reproduce in a garage. Sure, there were a few exotic steps like using a vacuum oven and a furnace with nitrogen, and you’d need some ability to handle chemicals like vinylidene fluoride. However, the hacker community has found ways to create lots of things with common tools, and we would imagine creating aerogels from some fruit ought not be out of reach.

Continue reading “Ultracapacitors Might Have Bad Fruity Smell” →