Generating random data is incredibly hard, and most of the random data around you isn’t truly random, but merely pseudo-random. For really random data, you’ll have to look at something like radioactive decay or *holds up spork* something like this. YouTube commenters will also suffice. The idea of using random data for generating musical notes is nothing new, but [Danny]’s experimental MIDI controller is something else. It’s a MIDI controller with the control removed, generating random musical notes based on radioactive decay.
The design of this controller is based on an off-the-shelf Geiger counter kit attached to an Arduino. The Arduino code simply counts up in a loop, and when the Geiger tube is triggered, an interrupt sets off a bit of code to generate a MIDI note. That’s simple enough, but where this project excels is its documentation. There’s a zine going through all the functions of this MIDI controller. There are single note or sequencer functions, a definable root note and scale type, an octave range, and velocity of the note can be set.
This is just a MIDI controller and doesn’t generate any noise on its own, but the video of the device in action shows off the range. [Danny] is getting everything from driving bass lines to strange ambient music out of this thing with the help of some synths and samplers. All the code and necessary files are available on the GitHub, with the video available below.
It may seem a paradox, but in the future tiny computers may dump electronics and return to their mechanical roots. At the macroscale, mechanical computers are fussy and slow, but when your area is down to a few molecules, electronics have trouble working but mechanical systems do just fine. In addition, these devices don’t use electricity directly, don’t generate electronic signatures, and may be less sensitive to things like radiation that damage electronics. A recent paper in Nature Communications discusses how to 3D print common logic gates using both macro-scale 3D printing techniques and a much smaller version with microstereolithography. You can see a video of gates in action below.
The gates use a bistable flexible mechanism. The larger gates use ABS plastic and measure about 250mm square. The smaller gate measures less than 25 mm square. They also use a special technique to make gates as small as 100 microns theoretically possible, although some of that is future work for the team.
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.
I’ve noticed that we hear a lot less from corporate research labs than we used to. They still exist, though. Sure, Bell Labs is owned by Nokia and there is still some hot research at IBM even though they quit publication of the fabled IBM Technical Disclosure Bulletin in 1998. But today innovation is more likely to come from a small company attracting venture capital than from an established company investing in research. Why is that? And should it be that way?
The Way We Were
There was a time when every big company had a significant research and development arm. Perhaps the most famous of these was Bell Labs. Although some inventions are inevitably disputed, Bell Labs can claim radio astronomy, the transistor, the laser, Unix, C, and C++ among other innovations. They also scored a total of nine Nobel prizes.
Bell Labs had one big advantage: for many years it was part of a highly profitable monopoly, so perhaps the drive to make money right away was less than at other labs. Also, I think, times were different and businesses often had the ability to look past the next quarter.
Fran Piernas likes to push the envelope a bit with projects that others might shy away from. A quick glance at his Hackaday.io profile reveals a few of the exciting projects he’s been working on recently, including a DIY X-ray machine and the high-voltage driver needed to run it. Not only that, he’s recently taken his home-brew X-ray rig to the next level – a computed tomography (CT) scanner. His YouTube channel also has some exciting stuff using potentially lethal voltages and ionizing radiation.
Please join us for this Hack Chat, in which we’ll cover:
How one safely works with high voltage and ionizing radiation;
Sourcing uncommon components like X-ray tubes;
How Fran decided to start playing at the edge of the danger zone; and
What sort of experiments he has in mind for the future.
You are, of course, encouraged to add your own questions to the discussion. You can do that by leaving a comment on the X-rays and high-voltage Hack Chat and we’ll put that in the queue for the Hack Chat discussion.
Click that speech bubble to the right, and you’ll be taken directly to the Hack Chat group on Hackaday.io. You don’t have to wait until Wednesday; join whenever you want and you can see what the community is talking about.
We all know CERN as that cool place where physicists play with massive, superconducting rings to smash atoms and subatomic particles to uncover secrets of matter in the Universe. To achieve this aim, they need to do a ton of research in other areas, such as development of special particle detectors.
While such developments are essential to the core research needs of the Centre, they also lead to spinoff applications for the benefit of society at large. One such outcome has been the Medipix Collaborations – a family of read-out chips for particle imaging and detection that can count single photons, allowing X-rays and gamma rays to be converted to electrical signals. It may not be possible for us hackers to get our hands on these esoteric sensors, but these devices are pretty interesting and deserve a closer look. Medipix sensors work like a camera, detecting and counting each individual particle hitting the pixels when its electronic shutter is open. This enables high-resolution, high-contrast, noise hit free images – making it unique for imaging applications.
Some months back, CERN announced the first 3D color X-ray of a human made possible using the Medipix devices. The result is a high-resolution, 3D, color image of not just living structures like bones, muscular tissues and vessels, but metal objects too like the wrist watch, seen in the accompanying photograph. The Medipix sensors have been in development since the 1990’s and are presently in their 4th “generation”. Each chip consists of a top semiconducting sensor array, made from gallium arsenide or cadmium telluride. The charge collected by each pixel is transported to the CMOS ASIC electronics via “bump bonds”. The integration is vertical, with each sensing pixel connected via the bump bond to an analog section followed by a digital processing layer. Earlier versions were limited, by technology, in their tiling ability for creating larger matrices of multiple sensors. They could be abutted on three sides only, with the fourth being used for on-chip peripheral logic and wire-bond pads that permit electronic read-out. The latest Medipix4 Collaboration, still under some development, eliminates this short coming. Through-silicon-via (TSV) technology provides the possibility of reading the chips through copper-filled holes that bring the signals from the front side of the chip to its rear. All communication with the pixel matrix flows through the rear of the chip – the peripheral logic and control elements are integrated inside the pixel matrix.
The Analog front end consists of a pre-amplifier followed by a window discriminator which has upper and lower threshold levels. The discriminator has four bits for threshold adjustment as well as polarity sensing. This allows the capture window to be precisely set. The rest of the digital electronics – multiplexers, shift registers, shutter and logic control – helps extract the data.
Further development of the Medipix (Tech Brief, PDF) devices led to a separate version called Timepix (Tech Brief, PDF). These new devices, besides being able to count photons, are capable of two additional modes. The first mode records “Time-Over-Threshold”, providing rough analog information about the energy of the photon. It does this by counting clock pulses for the duration when the signal stays above the discrimination levels. The other mode, “Time of Arrival”, measures arrival time of the first particle to impinge on the pixel. The counters record time between a trigger and detection of radiation quanta with energy above the discrimination level, allowing time-of-flight applications in imaging.
Medipix3 pixel schematic
Timepix2 pixel schematic
Besides medical imaging, the devices have applications in space, material analysis, education and of course, high energy physics. Hopefully, in a few years, hackers will lay their hands on these interesting devices and we can get to know them better. At the moment, the Medipix website has some more details and data sheets if you would like to dig deeper. For an overview on the development of such single photon detectors, check out this presentation from CERN – “Single X-Ray Photon Counting Systems: Existing Systems, Systems Under Development And Future Trends” (PDF).
On the face of it, powering most spacecraft would appear to be a straightforward engineering problem. After all, with no clouds to obscure the sun, adorning a satellite with enough solar panels to supply its electrical needs seems like a no-brainer. Finding a way to support photovoltaic (PV) arrays of the proper size and making sure they’re properly oriented to maximize the amount of power harvested can be tricky, but having essentially unlimited energy streaming out from the sun greatly simplifies the overall problem.
Unfortunately, this really only holds for spacecraft operating relatively close to the sun. The tyranny of the inverse square law can’t be escaped, and out much beyond the orbit of Mars, the size that a PV array needs to be to capture useful amounts of the sun’s energy starts to make them prohibitive. That’s where radioisotope thermoelectric generators (RTGs) begin to make sense.
RTGs use the heat of decaying radioisotopes to generate electricity with thermocouples, and have powered spacecraft on missions to deep space for decades. Plutonium-238 has long been the fuel of choice for RTGs, but in the early 1990s, the Cold War-era stockpile of fuel was being depleted faster than it could be replenished. The lack of Pu-238 severely limited the number of deep space and planetary missions that NASA was able to support. Thankfully, recent developments at the Oak Ridge National Laboratory (ORNL) appear to have broken the bottleneck that had limited Pu-238 production. If it pays off, the deep space energy crisis may finally be over, and science far in the dark recesses of the solar system and beyond may be back on the table.
Some months back, CERN announced 
The Analog front end consists of a pre-amplifier followed by a window discriminator which has upper and lower threshold levels. The discriminator has four bits for threshold adjustment as well as polarity sensing. This allows the capture window to be precisely set. The rest of the digital electronics – multiplexers, shift registers, shutter and logic control – helps extract the data.
