Cheap piezo buzzers are everywhere. They’re so cheap that they can be used in novelty birthday cards. Applying an alternating voltage across a piezo crystal makes it expand and contract, and fixing this crystal to a metal disk gives the piezo speaker its characteristic tinny sound that is anything but pleasant.
The piezoelectric effect works the other way too, and piezo elements are very useful as vibration sensors. Simply put one of your voltmeter leads on each of the piezo element’s wires and touch the element with your hand or knock it against your bench. You should see a voltage spike on your voltmeter which will change in magnitude with the amount of force you use when touching the element.
This ability to change shape when a voltage is applied and to create a voltage when they’re deformed is the basis of the piezoelectric transformer (PZT). While searching for a high voltage/low current transformer, Hackaday reader [Josh] was surprised to find a piezoelectric solution. He didn’t say whether he decided to use a PZT in his project but he did link us to a decent PDF on the subject.
In a PZT, two piezo elements sit next to each other. The primary is made up of multiple thin layers that expand horizontally and press on a single secondary piezo element. The more and the thinner the primary layers, the more force is exerted on the secondary, and the more voltage it develops. There are a few equations involved which you can check out in the PDF linked above that go over this concept in painful detail if you’re into that sort of thing.
If you have never played with piezo element you should add one to your next parts order. They are cheap and easy to experiment with. We have seen piezo elements used in DIY speakers, sonar projects, and even as the sensor for an atomic force microscope, but we have yet to see a piezoelectric transformer in a hack. Surely someone has used one in a project they worked on, leave us a link in the comments if you’re the person we’re talking about.
Slowly, Raspberry Pi Zeros are falling into the hands of everyone who wants one. Quickly, though, it was realized that one USB port wasn’t enough, and having a single USB OTG port was only just the most economical solution. The Pi Zero does have a lot of test points exposed on the back, and [Peter van der Walt] is clever enough to come up with a 4-port hub you can solder directly to the Pi Zero.
[Peter] has a bit of experience with USB ports on the Pi, and the test points available on the bottom of this cheap and wonderful board provide everything you need to break out the single USB OTG port to a USB hub. We’ve seen this done before with a few tenuous solder connections between the Zero and an off-the-shelf USB hub. [Peter]’s build does it by soldering a USB hub directly to the Pi through these test points. It’s the first purpose built bit of hardware designed for the express purpose of giving the Pi four USB ports while only making it a sliver thicker.
The chip [Peter] is using for the build is the TI TUSB2046B, a device that turns a single USB port into a 4-port hub. This is a part that only costs about $2 in quantity, and the USB connectors themselves are only about $0.60 if you want to build a thousand of these solderable USB hubs. Now you see why the Pi Foundation didn’t include a whole host of ports on the Pi Zero, but it does mean you should be able to pick this board up for under $10 when it’s inevitably cloned in China.
[Peter] doesn’t have this board working yet. In fact, he’s only just sent the Gerbers off to the PCB fab. There will be an update once [Peter] gets the boards back and solders up the tiny but tolerable 0603 parts.
Right up front, we’ll cop to the inevitable “not a hack” comments on this one. This video of the Steam Controller assembly plant is just two minutes of pure robotics porn, plain and simple.
From injection molding of the case parts through assembly, testing and final palletizing of packaged controllers for the trip to distributors, Valve’s video is amazingly detailed and very well made. We’d wager that the crane shots and the shots following product down conveyors were done with a drone. A grin was had with the Aperture Labs logo on the SCARA arms in the assembly and testing work cell, and that inexplicable puff of “steam” from the ceiling behind the pallet in the final shot was a nice touch too. We also enjoyed the all-too-brief time-lapse segment at around 00:16 that shows the empty space in Buffalo Grove, Illinois being fitted out.
This may seem like a frivolous video, but think about it: if you’re a hardware hacker, isn’t this where you want to see your idea end up? Think of it as inspiration to get your widget into production. You’ll want to get there in stages, of course, so make sure you check out [Zach Fredin]’s 2015 Hackaday Superconference talk on pilot-scale production.
If you’re looking for the future of humanity, look no further than the first plasma generated in the Wendelstein 7-X Stellerator at the Max Planck Institute for Plasma Physics. It turned on for the first time yesterday, and while this isn’t the first fusion power plant, nor will it ever be, it is a preview of what may become the invention that will save humanity.
A glimpse of plasma in side the Stellerator
For a very long time, it was believed the only way to turn isotopes of hydrogen into helium for the efficient recovery of power was the Tokamak. This device, basically a hollow torus lined with coils of wire, compresses plasma into a thin circular string. With the right pressures and temperatures, this plasma will transmute the elements and produce power.
Tokamaks have not seen much success, though, and this is a consequence of two key problems with the Tokamak design. First, we’ve been building them too small, although the ITER reactor currently being built in southern France may be an exception. ITER should be able to produce more energy than is used to initiate fusion after it comes online in the 2020s. Tokamaks also have another problem: they cannot operate continuously without a lot of extraneous equipment. While the Wendelstein 7-X Stellerator is too small to produce a net excess of power, it will demonstrate continuous operation of a fusion device. [Elliot Williams] wrote a great explanation of this Stellerator last month which is well worth a look.
While this Stellerator is just a testbed and will never be used to generate power, it is by no means the only other possible means of creating a sun on Earth. The Polywell – a device that fuses hydrogen inside a containment vessel made of electromagnets arranged like the faces of a cube – is getting funding from the US Navy. Additionally, Lockheed Martin’s Skunk Works claims they can put a 100 Megawatt fusion reactor on the back of a truck within a few years.
The creation of a fusion power plant will be the most important invention of all time, and will earn the researchers behind it the Nobel prize in physics and peace. While the Wendelstein 7-X Stellarator is not the first fusion power plant, it might be a step in the right direction.
There is surprising variation in the performance of SD cards. They are not all created equal and the differences can impact the running of your Raspberry Pi, no matter which model. [Jeff Geerling] wondered exactly how different cards would affect system performance. He ran a number of tests on cards ranging from cheap no-names to well-known brand names. The no-name cards fared pretty badly but even among the brand names there is considerable variation.
[Matt] over at Raspberry Pi Spy also tested SD cards and found similar differences. Both tested microSD cards. [Jeff’s] tests were solely on the Pi while [Matt’s] were on Windows 7, Ubuntu, and a Pi.
The discussions in the blog about what to measure were as interesting as the actual results. That lead to determining which software tools to use for the measurement. For example, a system doing a lot of small database reads and writes might work better with one SD card while a system storing and then streaming videos might work better with another card. Another interesting result is that the Pi’s data bus greatly limits the access speeds. [Jeff] measured much higher speeds running the same tests using a Mac with a USB dongle. The cards are capable of much more than the Pi can deliver.
[Matt] also checked the capacity of the SD cards. There are a lot of fakes floating around marked with higher capacities than they actually support. Even getting a brand name card may not help since some are counterfeit. So beware: if the price it too good to be true, it very well may be.
Motors are everywhere; DC motors, AC motors, steppers, and a host of others. In this article, I’m going to look beyond these common devices and search out more esoteric and unusual electronic actuators that might just find a place in one of your projects. In any case, their mechanisms are interesting in their own right! Join me after the break for a survey of piezo, magnetostrictive, magnetorheological, voice coils, galvonometers, and other devices. I’d love to hear about your favorite actuators and motors too, so please comment below!
Piezoelectric materials sometimes seem magic. Apply a voltage to a piezoelectric material and it will move, as simple as that. The catch of course is that it doesn’t move very much. The piezoelectric device you’re probably most familiar with is the humble buzzer. You’d usually drive these with less than 10 volts. While a buzzer will produce a clearly audible sound you can’t really see it flexing (as it does shown above).
To gauge the motion of a buzzer I recently attempted to drive one with a 150 volt piezo driver, this resulted in a total deflection of around 0.1mm. Not very much by normal standards!
The PiezoMotor LEGS actuator “walks” along a rod, pushing it as it goes.
For some applications however resolution is of primary interest rather than range of travel. It is here that piezo actuators really shine. The poster-boy application of piezo actuators is perhaps the scanning probe microscope. These often require sub-nanometer accuracy (less than 1000th of 1000th of 1 millimeter) in order to visualize individual atoms. Piezo stacks are ideal here (though hackers have also used cheap buzzers!).
Sometimes though you need high precision over a larger range of travel. There are a number of piezo configurations that allow this. Notably Inchworm, “LEGS”, and slip-stick actuators.
The PiezoMotor LEGS actuator is shown to the above. As noted, Piezos only produce small (generally sub-millimeter) motion. Rather than using this motion directly, LEGS uses this motion to “walk” along a rod, pushing it back and forth. The rod is therefore moved, in tiny nanometer steps. However, piezos can move quickly (flexing thousands of times a second). And the LEGS (and similar Inchworm actuator) allows relatively quick, high force, and high resolution motion.
The tablecloth trick (yes this one’s fake, the kid is ok don’t worry. :))
Another type of long travel piezo actuator uses the “stick-slip phenomenon”. This is much like the tablecloth magic trick shown above. If you pull the cloth slowly there will be significant friction between the cloth and this crockery and they will be dragged along with the cloth. Pull it quickly and there will be less friction and the crockery will remain in place.
This difference between static and dynamic friction is exploited in stick-slip actuators. The basic mechanism is shown in the figure below.
Motion caused by a stick-slip motor
When extending slowing a jaw rotates a screw, but if the piezo stack is compressed quickly the screw will not return. The screw can therefore be made to rotate. By inverting the process (extending quickly, then compressing slowly) the process is reversed and the screw is turned in the opposite direction. The neat thing about this configuration is that it retains much of the piezo’s original precision. Picomotors have resolutions of around 30 nanometer over a huge range of travel, typically 25mm, they’re typically used for optical focusing and alignment and can be picked up on eBay for 100 dollars or so. Oh and they can also be used to make music. Favorites include Stairway to Heaven, and not 1 but 2 versions of Still Alive (from Portal). Obligatory Imperial March demonstration is embedded here:
There are numerous other piezo configurations, but typically they are used to provide high force, high precision motion. I document a few more over on my blog.
Magnetostrictive actuators
Magnetostriction is the tendency of a material to change shape under a magnetic field. We’ve been talking about magnetostriction quite a lot lately. However much like piezos it can also be used for high precision motion. Unlike piezos they require relatively low voltages for operation and have found niche applications.
Magnetorheological motion
Magnetorheological (MR) fluids are pretty awesome! Much like ferrofluids, MR fluids respond to changes in magnetic field strength. However, unlike ferrofluids it’s their viscosity that changes.
This novel characteristic has found applications in a number of areas. In particularly the finishing of precise mirrors and lens used in semiconductor and astronomical applications. This method uses an electromagnet to change the viscosity of the slurry used to polish mirrors, removing imperfections. The Hubble telescope’s highly accurate mirrors were apparently finished using this technique (though hopefully not that mirror). You can purchase MR fluid in small quantities for a few hundred dollars.
Electrostatic motors
While magnetic motors operate through the attraction and repulsion of magnetic fields, electrostatic motors exploit the attraction and repulsion of electric change to produce motion. Electrostatic forces are orders or magnitude smaller that magnetic ones. However they do have niche applications. One such application is MEMS motors, tiny (often less than 0.01mm) sized nanofabricated motors. At these scales electromagnetic coils would be too large and specific power (power per unit volume) is more important than the magnitude of the overall force.
Voice coils and Galvanometers
The voice coil is your basic electromagnet. They’re commonly used in speakers, where an electromagnet in the cone reacts against a fixed magnet to produce motion. However voice coil like configurations are used for precise motion control elsewhere (for example to focus the lens of an optical drive, or position the read head of a hard disc drive). One of the cooler applications however is the mirror galvanometer. As the name implies the device was originally used to measure small currents. A current through a coil moved a rod to which a mirror was attached. A beam of light reflect off the mirror and on to a wall effectively created a very long pointer, amplifying the signal.
These days ammeters are far more sensitive of course, but the mirror galvanometer has found more entertaining applications:
High speed laser “galvos” are used to position a laser beam producing awesome light shows. Modern systems can position a laser beam at kilohertz speeds, rendering startling images. These systems are effectively high speed vector graphic like line drawing systems, resulting in a number of interesting algorithmic challenges. Marcan’s OpenLase framework provides a host of tools for solving these challenges effectively, and is well worth checking out.
In this article I’ve tried to highlight some interesting and lesser known techniques for creating motion in electronic systems. Most of these have niche scientific, industrial or artistic applications. But I hope they also also offer inspiration as you work on your own hacks! If you have a favorite, lesser known actuator or motor please comment below!
These are the times that we live in: the Raspberry Pi Zero comes out — a full freaking Linux computer on a chip for $5 — and people complain that it doesn’t have this or that. Top place on the list of desiderata is probably a tie between audio out and WiFi connectivity. USB is a solution for both of these, but with one USB port it’s going to be a scarce commodity, so any help is welcome.
Hackaday.io hacker [ajlitt] is looking for a way out of the WiFi bind. His solution? The Raspberry Pi series of chips has a special function on a bunch of the GPIO pins that make it easier to talk to SDIO devices. SDIO is an extension of the SPI-like protocol that’s used with SD memory cards. The idea with SDIO was that you could plug a GPS or something into your PDA’s SD card slot. We don’t have PDAs anymore, but the SDIO spec remains.
[ajlitt] dug up an SDIO driver for the ESP8089 chip, and found that you can liberate the ESP8266’s SPI bus by removing a flash memory chip that’s taking up the SPI lines. Connect the SPI lines on the ESP8266 to the SDIO lines on the Raspberry Pi, and the rest is taken care of by the drivers. “The rest”, by the way, includes bringing the ESP’s processor up, dumping new firmware into it over the SPI/SDIO lines to convince it to act as an SDIO WiFi adapter, and all the rest of the hardware communication stuff that drivers do.
The result is WiFi connectivity without USB, requiring only some reasonably fine-pitch soldering, and unlike this hack you don’t have to worry about USB bus contention. So now you can add a $2 WiFi board to you $5 computer and you’ve still got the USB free. It’s not as fast as a dedicated WiFi dongle, but it gets the job done. Take that, Hackaday’s own [Rud Merriam]!
In a PZT, two piezo elements sit next to each other. The primary is made up of multiple thin layers that expand horizontally and press on a single secondary piezo element. The more and the thinner the primary layers, the more force is exerted on the secondary, and the more voltage it develops. There are a few equations involved which you can check out in the PDF linked above that go over this concept in painful detail if you’re into that sort of thing.
This novel characteristic has found applications in a number of areas. In particularly the finishing of precise mirrors and lens used in semiconductor and astronomical applications. This method uses an electromagnet to change the viscosity of the slurry used to polish mirrors, removing imperfections. The Hubble telescope’s highly accurate mirrors were apparently finished using this technique (though hopefully not 
