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Hackaday Prize Entry: Bypassing TV broadcasting restrictions

พฤ, 09/29/2016 - 12:00

It’s a common problem faced by TV viewers, the programming they want to watch is being broadcast, but not to their location. TV content has traditionally been licensed for transmission by geography, and this has sometimes put viewers at odds with broadcasters.

The viewing public have not always taken this restriction of their programming choice lying down, and have adopted a variety of inventive solutions with varying degrees of legality and success. Many years ago you might have seen extreme-length UHF antennas to catch faraway transmitters, more recently these efforts have been in the digital domain. It was said in the 1990s that Sky’s Videocrypt satellite TV smart cards were cracked because German Star Trek Next Generation fans were unable to buy subscriptions for non-UK addresses, for example. You can argue in the comments over whether [Patrick Stewart] et al being indirectly responsible for a decryption coup is an urban legend, but it is undeniable that serial smart card emulators and dodgy DOS software for Sky decryption were sold all over Europe at the time.

Modern-day efforts to break the geographic wall on TV broadcasting have turned to the Internet. Services such as the ill-fated Aereo and the Slingbox set-top streaming products have taken the TV broadcast in a particular area and transported it to other locations for viewing online. But they are not the only Internet self-streaming option, if the idea of paying a subscription or tying yourself to a commercial service does not appeal then you can build an off-air streamer for yourself.

[Solenoid]’s project is an off-air streamer using a Raspberry Pi 3 with a USB DVB-T tuner. It uses Tvheadend to power the streaming, and OpenVPN to provide security. His build logs detail his efforts to ensure that power consumption is not too high and that the Pi is not running too hot, and provides instructions on how to set up and use the software. It’s not an overly complex piece of hardware, but it could provide a useful service for any of you who wish to keep up-to-date with your home TV when you are off on your travels.

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Filed under: video hacks

Listen to the Sun, Saturn, and the Milky Way with Your Own Radio Telescope

พฤ, 09/29/2016 - 09:00

Students from the Indian Institute of Science Education and Research combined a commercial satellite dish, a satellite finder and an Arduino, and produced a workable radio telescope. The satellite dish provides the LNB (low noise block) and the associated set-top box is used only for power.  Their LNB employs an aluminum foil shield to block extraneous signals.

In addition to the hardware, the team built Python software to analyze the data and show several practical applications. They used known geostationary satellites to calibrate the signal from the finder (digitized by the Arduino) to determine power per unit voltage. They also calculated the beam width (about 3.4 degrees) and used the sun for other calibration steps.

The paper notes that some designs use the ubiquitous RTL-SDR, but this limits the bandwidth to about 3 MHz. The satellite finder detector is inherently broadband and the team claims a bandwidth for their scope of 1.1 GHz. Some designs (like the Itty Bitty) use a dual LNB to have both. If you are too lazy to build any hardware, you can still get into the radio telescope data crunching game.

If you want an introduction to radio astronomy, you might enjoy Dr. John Morgan’s lecture, in the video below.

Filed under: Arduino Hacks, radio hacks

808 Drum Machine In An ATTiny 14-Pin Chip

พฤ, 09/29/2016 - 06:00

You may not know the 808 drum machine, but you have definitely heard it: the original Roland TR-808 was the first programmable drum machine and has been a mainstay of electronic music ever since. Hackers have been building their own versions of this vintage device for years, but this version from do-it-yourself synth builder [Jan Ostman] is quite remarkable.

He’s packed the entire device (called the Drum8 Vintage) into a single ATtiny84 14-pin DIP package, including the samples and eight polyphonic voices, plus old-school analog CV triggers, a global tune and an analog global accent input. That won’t mean a lot to non-musicians, but suffice to say that these are the same inputs that the original TR-808 had that allowed you to do all sorts of interesting stuff to trigger and modify the drum sounds. Plus some extras.

[Jan] is offering the chip itself for $20, and has made a limited edition version that is built into a patch bay panel for that genuine hard-wired look for $99. If you want to go the home-made route and make your own, he’s released the source code and schematics for making your own. You can check out more of [Jan’s] work in this post on making your own open-source instruments from Elliot. Thanks, Jan!

Filed under: musical hacks, news

SIM Card Connectors and White PCBs Make Huge LED Snowflakes Happen

พฤ, 09/29/2016 - 03:00

[Mike Harrison] talked about designing and building a huge scale LED lighting installation in which PCBs were used as both electrical and mechanical elements, and presented at Electromagnetic Field 2016. The project involved 84,000 RGBW LEDs, 14,000 microcontrollers and 25,000 PCBs. It had some different problems to solve compared to small jobs, but [Mike] shared techniques that could be equally applied to smaller scale projects or applications. He goes into detail on designing for manufacture and assembly, sourcing the parts, and building the units on-site.

The installation itself was a snowflake display for a high-end shopping mall in Hong Kong in the 2015 Christmas season. [Mike] wanted a small number of modular boards that could be connected together on-site to make up the right shapes. In an effort to minimize the kinds of manufacturing and parts needed, he ended up using modular white PCBs as structural elements as well as electrical. With the exception of some minor hardware like steel wire supports, no part of the huge snowflakes required anything outside of usual PCB manufacturing processes to make. The fewer suppliers, the fewer potential problems. [Mike] goes into design detail at 6:28 in the video.

For the connections between the boards, he ended up using SIM card connectors intended for cell phones. Some testing led to choosing a connector that matched up well with the thickness of a 1.6mm PCB used as a spacer. About 28,000 of them were used, and for a while in 2015 it was very hard to get a hold of that particular part, because they had cleaned everyone out!

About half-way through the video (10:55) [Mike] goes into microcontroller and firmware details. The PIC12F1501 turned out to be a great fit for reasons that included cost, wide operating voltage range, 10-bit PWM for each of Red, Green, Blue, and White, and the low cost of having Microchip program the firmware in at the factory. RGBW LEDs were chosen for a number of reasons, but mainly because the white generated is much more visually consistent across a large display (compared to lighting each of the RGB elements to make white.) He made sure that it was easy to reprogram the firmware across all units easily if needed, because updating thousands of microcontrollers one at a time is just not an option.

Video of the presentation is embedded below, but if you want to go straight to some video of the finished installation, it starts at 21:38.

Using PCB material as a structural component has a lot of potential. We’ve seen it in this clever tiny 7-segment display, and more recently in PocketNC’s FR4 Machine Shield. If you’re interested in trying it yourself, you can learn all about the finer points of how to use FR4 for enclosures.

Filed under: led hacks, Tech Hacks

Prusa Releases 4-Extruder Upgrade

พฤ, 09/29/2016 - 01:31

Let’s talk multi-material printing on desktop 3D printers. There are a lot of problems when printing in more than one color. The easiest way to do this is simply to add another extruder and hotend to a printer, but this reduces the build volume, adds more mass to the part of the printer that doesn’t need any more mass, and making sure each nozzle is at the correct Z-height is difficult. The best solution for multi-material printing is some sort of mixing hotend that only squirts plastic from one nozzle, fed by a Bowden system.

[Prusa], the man, not the printer, has just released a multi-material upgrade for the Prusa i3 mk2. This upgrade allows the i3 mk2 to print in four colors using only one hotend, and does it in a way that allows anyone to turn their printer into a multi-material powerhouse.

The basic idea behind this multi-material upgrade is a four-way Y-shaped filament path. Each color of filament is loaded into a separate extruder, and when the material is changed the currently ‘active’ filament is retracted out of the heater block to just before where the filament paths cross. After the filament is swapped in the hotend, the remainder of the previous color of filament is squirted out onto a small (3x5cm) tower.

Because this is an upgrade to the i3 mk2, Prusa needed a way to add three additional stepper motors to the build without having to replace the printer’s electronics board. He’s doing this with an SSR-based multiplexer that allows one stepper motor output and a few GPIOs to control four motors.

If you have an i3 mk2, a four- material upgrade for your printer will be available for $249 USD in a few months. That means a full color, four-extruder i3 mk 2 costs less than $1000 USD, a price no other multi-material printer can touch.

You can check out [Prusa’s] video of the multi-material upgrade below. The printer and the man will be touring the US for Maker Faire and Open Hardware Summit, and you can bet we’re going to get some video of this multi-material printer in action.

Filed under: 3d Printer hacks

Ask Hackaday: How Do You Make A Hotplate?

พฤ, 09/29/2016 - 00:01

Greetings fellow nerds. The Internet’s favorite artificial baritone chemist has a problem. His hotplates burn up too fast. He needs your help to fix this problem.

[NurdRage] is famous around these parts for his very in-depth explorations of chemistry including the best ways to etch a PCB, building a thermometer probe with no instructions, and chemical synthesis that shouldn’t be performed by anyone without years of experience in a lab. Over the past few years, he’s had a problem: hotplates suck. The heating element is usually poorly constructed, and right now he has two broken hotplates on his bench. These things aren’t cheap, either: a bare-bones hotplate with a magnetic stirrer runs about $600.

Now, [NurdRage] is asking for help. He’s contacted a few manufacturers in China to get a hundred or so of these hotplate heating elements made. Right now, the cost for a mica and metal foil hotplate is about $30 / piece, with a minimum order quantity of 100. That’s $3,000 that could be better spent on something a bit more interesting than a heating element, and this is where you come in: how do you build the heating element for a hotplate, and do it cheaply?

If you buy a hotplate from the usual lab equipment supplier, you’ll get a few pieces of mica and a thin trace of metal foil. Eventually, the metal foil will oxidize, and the entire hotplate will stop working. Repairs can be done with copper tape, but by the time that repair is needed, the heating element is already on its way out.

The requirements for this heating element include a maximum temperature of around 350 ºC. That’s a fair bit hotter than any PCB-based heat bed from a 3D printer gets, so consider that line of reasoning a dead end. This temperature is also above what most resins, thermoplastics, and composites can handle, which is why these hotplates use mica as an insulator.

Right now, [NurdRage] will probably end up spending $3,000 for a group buy of these heating elements. That’s really not that bad – for the price of five hotplates, he’ll have enough heating elements to last through the rest of his YouTube career. There must be a better way, though, so if you have an idea of how to make a high-temperature heating element the DIY way, leave a note in the comments.

Filed under: Ask Hackaday, Hackaday Columns

New SuperCon Badge is 40% Lighter and a Work of Art

พุธ, 09/28/2016 - 22:31

The 2016 Hackaday SuperConference is just around the corner and today we get a good look at the hardware badge. It was designed by [Voja Antonic] — a legend of hardware creation who will be at the conference. I like to think of him as the Woz of the Eastern Bloc, having designed the Galaksija computer. This badge is a beautiful example of embedded design. We’ll dive into all of the details after the break.

Get your ticket now for 48-hours of talks, workshops, the Hackaday Prize party, badge hacking,  and so much more.

This badge hosts an 8×16 surface-mount LED matrix, four user buttons (plus reset and wake-from sleep), IR communications, and a three-axis accelerometer, all driven by a PIC18LF25K50, powered by two AAA batteries, and programmed via USB. That’s a mouthful of delightful hardware.

[Voja Antonic] based the design on the badge that he developed for the Hackaday Belgrade Conference in April (shown on the left). That was a stellar badge design, and [Voja] managed to improve on it for this one. I really like the edge-mounted single-AAA battery holders which, along with the replacement of the LED modules, cuts down on the thickness of the badge. They also reduce the weight, from 88 grams to 52 grams. Those with keen ears will note that I incorrectly quoted 62 grams in the video but the lower figure is correct.

There will be a few changes from what you see here. If you look closely you can see an acrylic bezel around the LEDs. On the final badge this will host an acrylic diffuser. This prototype, originally spun in June, has the incorrect location printed on it. The SuperCon will be in Pasadena, CA on November 5 & 6, 2016.

The badges are interactive. A kiosk at the conference will let you store your own scrolling messages on the badge. And if you’re really clever you can figure out how to make your badge prank those other people are wearing. The IR comms feature is also how you take part in the crypto challenge. [Voja] has cooked up some fun by placing badges around the conference with puzzles stored on them. Write a program to your badge to interact with them and decipher what is sent back. This was hugely popular in Belgrade and will be even better at SuperCon!

The nine-pin expansion header on the back is one more way that this badge is designed for hackability. We had such a great time last year with the bare-PCB hardware hacking it was important to provide direct access to the hardware on this badge. As with the amazing badge hacking of the Belgrade Conference, this badge is running a bootloader. It tends all of the hardware, providing memory-mapped access to the display, buttons, and peripherals. This means if you’ve never blinked an LED you will get up and running quickly. More seasoned programmers won’t have to get bogged down with low-level coding, and wizened experts can blow out the bootloader and go bare metal (don’t forget your PICkit).

I want to take a moment to showcase the craftsmanship of this badge. Check out the layout, and the aesthetic — this is a thing of beauty. Now take a really close look at that LED matrix (click to embiggen). When [Voja] first sent me the prototype I thought there was some solder balls stuck to the flux. Wrong. What looks like a stray cat hair or solder splash is a tiny wire — ninja-level rework that [Voja] performed by hand before shipping this my way. Check out some of the other projects he’s posts.

I love this badge. It really has pulled in the best of what we’ve done at the last two conferences. The only sure way to get your hands on one is to show up at SuperCon. Get your tickets now!

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Filed under: cons, Featured

Chemical Formulas 101

พุธ, 09/28/2016 - 21:01

It seems like every other day we hear about some hacker, tinkerer, maker, coder or one of the many other Do-It-Yourself engineer types getting their hands into a complex field once reserved to only a select few. Costs have come down, enabling common everyday folks to equip themselves with 3D printers, laser cutters, CNC mills and a host of other once very expensive pieces of equipment. Getting PCB boards made is literally dirt cheap, and there are more inexpensive Linux single board computers than we can keep track of these days. Combining the lowering hardware costs with the ever increasing wealth of knowledge available on the internet creates a perfect environment for DIYers to push into ever more specific scientific fields.

One of these fields is biomedical research. In labs across the world, you’ll find a host of different machines used to study and create biological and chemical compounds. These machines include DNA and protein synthesizers, mass spectrometers, UV spectrometers, lyophilizers, liquid chromatography machines, fraction collectors… I could go on and on.

These machines are prohibitively expensive to the DIYer. But they don’t have to be. We have the ability to make these machines in our garages if we wanted to. So why aren’t we? One of the reasons we see very few biomedical hacks is because the chemistry knowledge needed to make and operate these machines is generally not in the typical DIYers toolbox. This is something that we believe needs to change, and we start today.

In this article, we’re going to go over how to convert basic chemical formulas, such as C9H804 (aspirin), into its molecular structure, and visa versa. Such knowledge might be elementary, but it is a requirement for anyone who wishes to get started in biomedical hacking, and a great starting point for the curious among us.

Lewis Dots Source

One of the goals of the chemist is to understand how elements and molecules interact with each other. Atoms will always combine to form a more stable electron structure, and be isoelectronic with the noble gases. It’s the outermost, or valance electrons that interact during bonding, and many chemists find it useful to depict these valence electrons as dots around the atom’s symbol when drawing out chemical formulas. One can look to the periodic table for the atom’s symbol, but can also look at the group number to learn the number of valence electrons in an element. For the main group elements (group A), the group number is the same as the valance electron number. The transition metals (group B) are not usually represented with Lewis dots. Take a look at the image on the upper right to get a clear understanding of how the dots represent the outermost electrons of an element, and how that number corresponds to the group number in the periodic table. Note that the dots are not paired until absolutely necessary.

Covalent Bonding

There are two main ways that atoms can bond with each other — covalent and ionic. Ionic bonding occurs when electrons from an atom that gives them up easily moves to another atom that accepts them easily. This causes an electrostatic charge to exist between them, which makes them stick together. Salt (NaCl) is an example of an ionic bond.

Covalent bonding occurs when atoms share electrons in order to become more stable, like a noble gas. Because noble gases have eight valence electrons, this tendency is referred to as the octet rule. This rule applies to many of the elements involved in biochemistry (such as carbon, nitrogen and oxygen), and allows us to predict how they will bond. Observing the Lewis Dots helps to visualize how covalent bonding occurs between these elements via the octet rule, allowing us to draw them as structures.

Lewis Structures

Water (H2O) is probably the best known example of a covalent bond. If we look at the Lewis dot symbol for oxygen, we see that it has 6 valence electrons (or dots). Hydrogen has one. From the oxygen’s viewpoint, it wants to achieve the noble gas structure of the noble gas neon, and it needs two electrons to achieve this. So it bonds with two hydrogen atoms. From the hydrogen’s viewpoint, it wants to achieve the electron state of helium. So it bonds with the oxygen atom. Each atom is in its most stable state — the noble gas configuration. When an electron is shared between the two atoms, the dot is replaced by a single line. See the image on the left.

Source via Study.com

The single line that represents the shared electron is known as a single bond. There can be cases of multiple bonds too. Consider ethylene (C2H4). Carbon has 4 valance electrons and hydrogen has one. The two carbon atoms share two electrons each, while each shares another two with two hydrogen atoms. This configuration puts each atom in its neon noble gas electron state. See the image on the right for the Lewis structure of ethylene.

Carbon is a unique element in biochemistry, as it can form nearly endless bonds with itself. In fact, an entire branch called organic chemistry is dedicated to the study of carbon and its derivatives. You will often hear chemists describe themselves as organic or inorganic – each branches into its own unique fields of research.

Benzene – C6H6

We all have come in contact with benzene in one way or another. It’s responsible for the odor of gasoline. But more importantly, it’s a key molecule in organic chemistry. It has the shape of a ring, and is known as an aromatic molecule. This means the electrons can move freely around the ring, giving it unique properties, such as enhanced stability. But to stay in line with Lewis structures; I bring up benzene because it is often drawn in a shorthand way that will confuse those who are unaware. To the right is a benzene molecule. But it is often drawn using the short hand shown just below.

[via ChemSpider]Note that aspirin (C9H8O4) contains a benzene ring. And now that you know what it is, you will see it in many chemical formulas.

Looking at the non-shorthand Lewis Structure, we see that the six carbons form a bond with each other, with each forming a single bond with a hydrogen atom. Three of the six bonds between the carbon atoms are double bonds. Again, all of this is done so that each atom is in its most stable noble gas state.

Step by Step

Let’s walk through an example of taking a chemical formula to a Lewis Structure. We’ll use H2O for our example

  1. Draw a skeletal structure. Use your new knowledge of the Lewis Dots to arrange the atoms so they’ll bond to satisfy the octet rule. Draw a single line (representing a shared electron) between each of the bonded atoms. With larger molecules, usually the atom with the smallest overall negative charge will be the center atom. For water, this would look like: H—O—H
  2. Find the total number of valence electrons. For water, this is 8.
  3. For each bond, represented by the single line, subtract 2. For water, 8 – 4 = 4.
  4. Use the value obtained in step 3 to fill the valence shell of the atoms bonded to the central atom. For water, the hydrogen atoms already have a full valence shell, so we will have leftover electrons.
  5. If any electrons remain, put them on the central atom (as dots). Water would have 4 dots placed on the oxygen atom.
  6. If at the end there are less than 8 electrons on the central atom, remove two of them from one of the outer atoms and make a double bond to the central atom.

I know this has been a review of high school chemistry for some, but it is necessary to understand these basic ideas before we move into things like proteins and carbohydrates. While we didn’t touch on everything, you should now have a basic idea of how to take a simple chemical formula to a Lewis structure, and vice versa. For a more advanced look at the electron structures of the elements and where they come from, see our periodic table post.

Filed under: chemistry hacks, Engineering, Featured, Original Art

Raspberry Pi Adds A Digital Dash To Your Car

พุธ, 09/28/2016 - 18:00

Looking for a way to make your older car more hi-tech? Why not add a fancy digital display? This hack from [Greg Matthews] does just that, using a Raspberry Pi, a OBD-II Consult reader and an LCD screen to create a digital dash that can run alongside (or in front of ) your old-school analog dials.

[Greg’s] hack uses a Raspberry Pi Foundation display, which includes a touch screen, so you don’t need a mouse or other controls. Node.js displays the speed, RPM, and engine temperature (check engine lights and other warnings are planned additions) through a webpage displayed using Chromium. The Node page is pulling info from another program on the Pi which monitors the CAN Consult bus. It would be interesting to adapt this to use with more futuristic displays, maybe something like a pico projector and a 1-way mirror for a heads-up display.

To power the system [Greg] is using a Mausberry power supply which draws power from your car battery, but which also cleanly shuts down the Pi when the ignition is turned off so it won’t drain your battery. When you throw in an eBay sourced OBD-II Consult reader and the Consult Dash software that [Greg] wrote to interpret and display the data from the OBD-II Consult bus, you get a decent digital dash display. Sure, it isn’t a Tesla touchscreen, but at $170, it’s a lot cheaper. Spend more and you can easily move that 60″ from your livingroom out to your hoopty and still use a Raspberry Pi.

What kind of extras would you build into this system? Gamification of your speed? Long-term fuel averaging? Let us know in the comments.

UPDATE – This post originally listed this hack as working from the OBD-II bus. However, this car does not have OBD-II, but instead uses Consult, an older data bus used by Nissan. Apologies for any confusion!

Filed under: car hacks, Raspberry Pi

Songbird, A Mostly 3D Printed Pistol That Appears To Actually Work

พุธ, 09/28/2016 - 15:01

[Guy in a garage] has made a 3D printed gun that not only appears to fire in the direction pointed, it can also do it multiple times. Which, by the standard of 3D printed guns, is an astounding feat. He started with .22 rifle cartridges but has since upgraded and tested the gun with .357 rounds. The link above is a playlist which starts of with an in-depth explanation of the .22 version and moves through design iterations

This gun prints on a standard FDM printer. Other 3D printable guns such as the infamous Liberator or the 3D printed metal gun need more exotic or precise 3D printing to work effectively. The secret to this gun’s ability is the barrel, which can be printed in nylon for .22 cartridges, or in ABS plus a barrel liner for .22 and .357 caliber.

A barrel liner is one way to repair a gun that has aged and is no longer shooting properly. Simply put, it is a long hardened metal tube with rifling on the inside. Some guns come out of the factory with one, and a gunsmith simply has to remove the old one and replace it. Other guns need to be bored out before a liner can be installed.

The metal liner surrounded by plastic offers enough mechanical strength for repeat firings without anyone losing a hand or an eye; though we’re not sure if we recommend firing any 3D printed gun as it’s still risky business. It’s basically like old stories of wrapping a cracked cannon in twine. The metal tries to expand out under the force of firing, but the twine, which would seem like a terrible material for cannon making, is good in tension and when wrapped tightly offers more than enough strength to hold it all together.

This is also how he got the .357 version to work. The barrel slots into the gun frame and locates itself with a rounded end. However, with the higher energy from a .357 round, this rounded end would act as a wedge and split the 3D printed frame. The fix for this was simple. Glue it back together with ABS glue, and then wrap the end of the assembly with a cable tie.

This is the first 3D printed gun we’ve seen that doesn’t look like a fantastic way to instantly lose your hand. It’s a clever trick that took some knowledge of guns and gunsmithing to put together. Despite the inevitable ethical, moral, and political debate that will ensue as this sort of thing becomes more prevalent, it is a pretty solid hack and a sign that 3D printing is starting to work with more formidable engineering challenges.

Filed under: 3d Printer hacks, weapons hacks

Hackaday Prize Entry: Under Cabinet LED Lighting Controller

พุธ, 09/28/2016 - 12:00

[Matt Meerian]’s workbench seems to be in perpetual shadow, so he has become adept at mounting LED strips under all his shelves and cabinets. These solve any problems involving finding things in the gloom, but present a new problem in that he risks a lot of LED strips being left on, and going round turning them all off is tedious.

His solution is to make a wireless controller for all his home LED strips, under the command of a web app from his Android tablet. An ESP8266 and a set of MOSFETs provide the inner workings, and the whole is presented on a very compact and well-designed purple OSH Park PCB reflow soldered on a $20 Wal-Mart hotplate and set in a plastic enclosure. The web interface is still in development, but has a fairly simple CSS front end for the ESP8266 code. All software, the schematic, and BoM can be downloaded from the Hackaday.io page linked above.

This project isn’t going to end world hunger or stop wars, but it’s beautifully done and well documented, and it makes [Matt]’s life a lot easier. And that makes it a good entry for the Hackaday Prize.

The HackadayPrize2016 is Sponsored by:
Filed under: led hacks

A Real Turn Off

พุธ, 09/28/2016 - 09:00

[Newbrain] had a small problem. He’d turn off the TV, but would leave the sound system turned on. Admittedly, not a big problem, but an annoyance, none the less. He realized the TV had a USB port that went off when it did, so he decided to build something that would sense when the USB port died and fake a button press into the amplifier.

He posted a few ideas online and, honestly, the discussion was at least as interesting as the final project. The common thread was to use an optoisolator to sense the 5 V from the USB port. After that, everyone considered a variety of ICs and discretes and even did some Spice modeling.

In the end, though, [Newbrain] took the easy way out. An ATtiny 84 is probably overkill, but it easy enough to press into service. With only three other components, he built the whole thing into a narrow 24-pin socket and taped it to the back of the audio unit’s wired remote control.

The seventh post contains the code for the CPU. It isn’t all that difficult or exciting, but the thought process of evaluating FETs and logic ICs against a cheap CPU is entertaining and maybe even instructive.

The amplifier’s wired remote acted like a potentiometer, interestingly enough, so it was a little different than what you would probably find on another piece of gear. We’ve looked at remote hacking several times. Unsurprisingly, the Arduino features in several of them — a small step up from the ATtiny84 used here.

Filed under: ATtiny Hacks

Line Follower with No Arduino

พุธ, 09/28/2016 - 06:00

There’s hardly a day that passes without an Arduino project that spurs the usual salvo of comments. Half the commenters will complain that the project didn’t need an Arduino. The other half will insist that the project would be better served with a much larger computer ranging from an ARM CPU to a Cray.

[Will Moore] has been interested in BEAM robotics — robots with analog hardware instead of microcontollers. His latest project is a sophisticated line follower. You’ve probably seen “bang-bang” line followers that just use a photocell to turn the robot one way or the other. [Will’s] uses a hardware PID (proportional integral derivative) controller. You can see a video of the result below.

Looking at how [Will] used simulation to devise a PID with opamps and a PWM generator is illustrative. As you can see from the video, the results are good.

We’ve looked at BEAM before. We’ve even seen mutants that combine traditional BEAM circuitry with microcontrollers. But it’s still nice to see the pure analog version running through its paces every once in a while.

Filed under: robots hacks, slider

New Part Day: Wireless BeagleBones On A Chip

พุธ, 09/28/2016 - 03:00

The BeagleBone is a very popular single board computer, best applied to real-time applications where you need to blink LEDs really, really fast. Over the years, the BeagleBone has been used for stand-alone CNC controllers, the brains behind very large LED installations, and on rare occasions has been used to drive CRTs. If you just want a small Linux board, get a Pi. If you want to do something interesting with hardware, get a BeagleBone.

The BeagleBone ecosystem has grown a lot in the last year, from the wireless and Grove connector equipped BeagleBone Green, the robotics-focused BeagleBone Blue, the Zoolander-inspired Blue Steel. Now there’s a new BeagleBone, built around a very interesting System on Module introduced earlier this year.

The new board is called the BeagleBone Black Wireless, and it brings to the table all you know and love about the BeagleBone. There’s a 1GHz ARM355x with two 32-bit 200MHz PRUs for the real-time pin toggling. RAM is set at 512MB, with 4GB of eMMC Flash and Debian pre-installed, and a microSD card for larger storage options. The new feature is wireless connectivity: a TI WiFi and Bluetooth module with provisions for 802.11s replaces the old Ethernet connector.

Taken at face value, the new BeagleBone Black Wireless deserves a mention — it’s a BeagleBone with wireless — but isn’t particularly noteworthy. But when you get to the gigantic brick of resin dropped squarely in the middle of the board does the latest device in the BeagleBone family become very, very interesting. The System on Module for this version of the BeagleBone is the BeagleBone On A Chip released a few months ago. The Octavio Systems OSD335x is, quite literally, a BeagleBone on a chip. It’s a BGA with big balls, making it solderable with hand-applied solder paste and a toaster oven reflow conversion. In fact, the BeagleBone Wireless was designed by [Jason Kridner] in Eagle as a 6-layer board. It’s still a bit beyond the standard capabilities of OSHPark, but the design can still be cut down, and shows how this BeagleBone on a Chip can be applied to other Open Hardware projects.

Filed under: Hackaday Columns, slider

Smart Sutures

พุธ, 09/28/2016 - 01:31

Researchers at Tufts University are experimenting with smart thread sutures that could provide electronic feedback to recovering patients. The paper, entitled “A toolkit of thread-based microfluidics, sensors, and electronics for 3D tissue embedding for medical diagnosis”, is fairly academic, but does describe how threads can work as pH sensors, strain gauges, blood sugar monitors, temperature monitors, and more.

Conductive thread is nothing new but usually thought of as part of a smart garment. In this case, the threads close up wounds and are thus directly in the patient’s body. In many cases, the threads talked to an XBee LilyPad or a Bluetooth Low Energy module so that an ordinary cell phone can collect the data.

Of course, sewing strange conductive thread into your body isn’t something most would try out on their own. Still, some of the thread techniques could be useful in other contexts.

We’ve looked at conductive thread several times in the past. We also saw conductive thread in a jacket to help kids learn to ski (which coincidentally used a Flora, similar to a LilyPad).

Filed under: Medical hacks, wearable hacks

Retrotechtacular: Power Driven Articulated Dummy

พุธ, 09/28/2016 - 00:01

If any of you have ever made a piece of clothing, you’ll know some of the challenges involved. Ensuring a decent and comfortable fit for the wearer, because few real people conform exactly to commercial sizes. It’s as much a matter of style as it is of practicality, because while ill-fitting clothing might be a sartorial fail, it’s hardly serious.

When the piece of clothing is a space suit though, it is a different matter. You are not so much making a piece of clothing as a habitat, and one that will operate in an environment in which a quick change to slip into something more comfortable is not possible. If you get it wrong at best your astronaut will be uncomfortable and at worst their life could be threatened.

PDAD’s arm mechanism, from the contemporary report.

In the early 1960s, NASA needed to quantify the effects of clothing such as a space suit on a human body. They could dress an astronaut in a suit, but while he could give them a subjective view of its comfort he could not quantise the forces it exerted on his body. Their solution to this problem was to construct a force gauge, an instrument designed to measure all the forces exerted by the suit as it simulated the full range of human movement. PDAD, the Power Driven Articulated Dummy, was the hydraulically driven humanoid result.

PDAD was designed to be adjustable to simulate a range of heights and sizes of typical American males, with a range of movement and torque capability as close as possible to those of a human within the constraints of the components available at the time. The actuators were hydraulic, and the control system was a fairly straightforward analogue servo system with an operator performing all the motions from a console. This meant that it was difficult for more than four joints to be in action at once, the limitation being the operator’s dexterity.

A close-up of the PDAD. Image: RR Auctions.

Two PDAD dummies were built during the programme, though problems with hydraulic leaks and overheating plagued their operation. Eventually NASA moved on from the project, and one of the dummies became part of the Smithsonian collection. The other found its way to the University of Maryland and thence to a private buyer, and is featured here because it is being auctioned later this month with an estimated price of $80,000. The auctioneer provides a wealth of photographs of the dummy, as well as PDFs of a contemporary engineering report on the project and period news coverage.

The PDAD dummy for sale is a little battered and worn, and seems to have lost its left elbow, forearm, and hand. There is no sign of the control console and it’s probably safe to guess that it’s not presented as a working example. However it is a fascinating glimpse into the depth and quality of the huge amount of work that went into the early years of human space flight, and if we are lucky it may find its way into another museum so we have the chance to see it at first hand.

The Smithsonian’s PDAD can be seen on their website, and is housed at the Steven F. Udvar-Hazy Center in Chantilly, VA. They provide the YouTube video shown below the break, of 1960s engineers testing the dummy.

Surprisingly this is the first time we’ve touched on the development of space suits here at Hackaday. We have however had a huge number of stories about other parts of the Apollo programme, which you can browse through the Apollo tag.

Via New Atlas, thanks: [Michael Boswell] for the tip.

Header image of the PDAD for sale: RR Auctions.

Filed under: classic hacks, Hackaday Columns, Retrotechtacular

3D Printed Acoustic Holograms: Totally Cool, Not Totally Useless

อังคาร, 09/27/2016 - 22:31

If you wave your hand under the water’s surface, you get a pattern of ripples on the surface shortly thereafter. Now imagine working that backwards: you want to produce particular ripples on the surface, so how do you wiggle around the water molecules underneath?

That’s the project that a crew from the University of Navarre in Spain Max Planck Institute for Intelligent Systems undertook. Working backwards from the desired surface waves to the excitation underwater is “just” a matter of math and physics. The question is then how to produce the right, incredibly irregular, wavefront. The researchers’ answer was 3D printing.

The idea is that, by creating the desired ripples on the water’s surface, the researchers will be able to move things around. We’ve actually seen this done before in air by [mikeselectricstuff], and a more sophisticated version from the University of Navarre in Spain uses multiple ultrasonic transducers and enables researchers to move tiny objects around in mid-air.

What’s cool about the work done underwater by the Navarre Max Planck Institute group is that all they’re doing is printing out a 3D surface and wiggling it up and down to make the waves. The resulting surface wave patterns are limited in comparison to the active systems, but the apparatus is so much simpler that it ought to be useful for hackers with 3D printers. Let the era of novelty pond hacking begin!

Filed under: news

Automatic Resistance: Resistors Controlled by the Environment

อังคาร, 09/27/2016 - 21:01

Resistors are one of the fundamental components used in electronic circuits. They do one thing: resist the flow of electrical current. There is more than one way to skin a cat, and there is more than one way for a resistor to work. In previous articles I talked about fixed value resistors as well as variable resistors.

There is one other major group of variable resistors which I didn’t get into: resistors which change value without human intervention. These change by environmental means: temperature, voltage, light, magnetic fields and physical strain. They’re commonly used for automation and without them our lives would be very different.


Thermistor, By Ansgar Hellwig [CC BY-SA 2.0 DE], via Wikimedia CommonsAs you can probably tell from part of the name, thermal, meaning “of or relating to heat”, these are resistors whose resistance changes with temperature. While that’s true of all resistors, with thermistors the change is larger and desired.

They come in two types:

  • NTC, or Negative Temperature Coefficient thermistors, where as the temperature increases their resistance decreases, and
  • PTC, or Positive Temperature Coefficient thermistors, where as the temperature increases their resistance increases.

Many Hackaday readers might be familiar with NTC thermistors in 3D printers where they’re used to measure the temperature of the hot end of the extruder. If your printer has a heated bed it is likely also monitored by an NTC.

And there are many more applications where they’re used for measuring temperature such as in digital thermometers, toasters, coffee makers, freezers, and so on.

But in addition to measuring temperature, NTC thermistors are also used for limiting current. As inrush current limiters they limit any rush of high current when a device is first turned on. Basically when the device is turned on, the thermistor is still relatively cool and so acts as a high resistance, limiting the current. Over time, as more current flows through the thermistor, its temperature increases and so its resistance decreases. That allows more current to flow through it, which is fine since the initial rush of high current is finished by that time.

My only experience with NTC thermistors was to play around with one that was part of an automotive sensor. The sensor was to be screwed into the engine compartment possibly for measuring the coolant or oil temperature. Of course this doesn’t measure the temperature directly. Instead a voltage is applied across it. As the temperature changes, the resistance changes and so does the voltage. The vehicle’s computer then uses a table or formula to map that voltage to a temperature.

I couldn’t find the datasheet for the automotive part and didn’t know the relationship between the thermistor’s temperature and resistance so I put it in a pot of water on the stove. As I slowly brought the water to a boil I measured the water temperature and the thermistor’s resistance, obtaining the chart shown here.

Positive Temperature Coefficient (PTC) thermistors, whose resistance increases as temperature increases, also have their uses.

One example is as a replacement for a fuse. As the current in a circuit increases, the temperature of the thermistor increases due to normal resistive heating. This heat is lost to the surroundings. But if the current is higher than it should be then at some point it will heat up faster than it can lose that heat. At that point the resistance will increase, limiting the current.

With the advent of flat panel displays there are fewer and fewer CRT displays around but some readers will remember that PTC thermistors were used in the display’s degaussing coil circuits. The degaussing coil would need to be energized briefly and turned off gradually. The current through the coil would create the needed magnetic field for degaussing, and the current would also heat up the thermistor. As it did, the thermistor’s resistance would increase in the desired gradual manner, reducing the current through the coil until the circuit shut off.


Varistor, By Michael Schmid [CC BY-SA 3.0], via Wikimedia Commons, and voltage-current graphThe name varistor doesn’t help much as the name’s origin comes from “varying resistor”, which is a description of all the parts covered in this article and the others in the series. A varistor’s resistance varies according to the voltage, so maybe remembering that it starts with a ‘V’ helps. In a varistor the higher the voltage, the lower the resistance, and the direction of the current doesn’t matter. It’s also much like a diode in that up to a certain minimum voltage it’s off and then turns on (see the voltage-current graph).

Most applications for varistors are in surge protection, protecting circuits from mains transients, inductive loads and from lightning. They’re usually placed across the circuit to be protected so that should the voltage rise high enough across it, the varistor will conduct and act as a short for the current, instead of the current going through the circuit.

My own experience with varistors comes from my time as a solar contractor. We’d attach lightning arresters to various components of the solar system: two arresters for the inverter, where one set of wires ran outdoors to a generator and another set went out to the loads in the cottage, and one arrester for the charge controller where wires ran out to the solar panels. These are all wire runs where voltage can be induced to damaging levels by nearby lightning.

Each of these lightning arresters contains a Metal Oxide Varistor (MOV). The varistor is connected between the wires and ground. As long as the voltage is low enough then current doesn’t conduct. But when lightning strikes somewhere nearby, the voltage on the wires rises and reaches a point where the varistor conducts to ground (e.g. 385 volts). This prevents the voltage from rising further. As long as the solar component is able to handle that voltage then it’s protected. With some standards, the solar component is designed to handle up to 2300 volts where these wires are connected.

Photoresistor/LDR Photoresistor

A photoresistor’s resistance decreases as light intensity increases. You may also see it referred to as an LDR (Light Dependent Resistor). Its resistance in the dark can be in the megaohms but with the correct wavelengths and sufficient intensity of light, it can be just a few ohms.

Photoresistors aren’t good for detecting rapid changes in light intensity. In going from complete darkness to light, there can be as much as a 10 millisecond delay before the resistance decreases fully. And when going from light to complete darkness the resistance can take as much as 1 second to increase to the megaohm range. However, there are applications where this delay is desireable such as with audio compression. Here an LED or electroluminescent panel is used to control the resistance of the photoresistor and affect the audio signal gain. Doing so is said to sound smoother by softening the attack and release than doing so without a photoresistor.

Another typical application is for a light sensor to detect if a night light should be turned on.

Laser communicator to photoresistor circuit

In my case I made a laser communicator that used an audio signal to modulate the output of a dollar store toy laser. I then shined that now fluctuating laser beam onto a distant photoresistor. The photoresistor was part of a circuit that fed an amplifier and the result was the audio signal transmitted by light and reproduced on the amplifier’s speaker. This violated what I mentioned above about not using them for rapid changes in light intensity, but it worked well enough as a fun experiment.

Magneto Resistive Sensor Magneto resistive sensor (KMT32B) from Digikey

The resistance of a magneto resistor can be used to detect the position, orientation and strength of a magnetic field. It uses the magnetoresistance effect. The anisotropic magnetoresistance (AMR) effect, discovered in the 1800s is sensitive to the magnetic field strength and the angle between an electric current and the magnetic field. There are other, more recently discovered effects but most conventional resistors use the AMR effect. Magneto resistive sensors that are built around these resistors are available from Digikey and Mouser among others.

I haven’t used magneto resistive sensors myself but one common application is as wheel speed sensors in automobiles. Others are magnetometry, various sensors for angle, rotation and linear positions, and for detecting vehicles on the road.

There is a lot of interesting potential applications for these sensors. At the 2013 Open Hardware Summit a 1-DOF haptick feedback kit called Hapkit was demonstrated by a group from Stanford. They used a magneto resistive sensor to detect a pendulum’s position. That position is then used by a microcontroller to power a motor to make moving the pendulum by hand feel like you’re moving a spring or click wheel.

Strain Gauges

Strain gauge interior, [CC BY-SA 2.5], via Wikimedia CommonsA strain gauge is an electrical conductor that changes resistance as it’s stretched or compressed, but without breaking, buckling or otherwise permanently deforming it. To get a large enough effect to make a useful change in resistance, the conductor is usually laid out in a zigzag or serpentine pattern with the long ends oriented in the direction of the expected strain.

The change in resistance is very small and so to aid measurement the strain gauge is incorporated in a Wheatstone bridge. A full article could be written about strain gauges and their use in Wheatstone bridges so here’s just a brief overview.

The Wheatstone bridge consists of two voltage dividers, R1 and R2 being one of them, and R3 and R4 being the other one. The input voltage, called the excitation voltage (VEx), is across the outside of the bridge, and the resulting output voltage (Vo) is taken from the centers of the two voltage dividers.

Wheatstone bridge and voltage output formula

The voltage output, Vo, can be calculated using the formula shown. If the ratio R1/R2 is equal to the ratio R4/R3 then calculating Vo you’ll find you get 0 volts. But if one of the resistors is replaced with a strain gauge then when it’s strained, Vo will become non-zero. Further formulas can be used to convert this to a value in a unit actually called ‘strain’.

Multiple strain gauges can also be used to further amplify the values and to compensate for temperature.

Strain gauges are found in load cells and pressure sensors, both often incorporated in Wheatstone bridges. The ones in pressure sensors are usually made with silicon, polysilicon, metal film, thick film or bonded foil.


And that concludes this series on resistors. The other two articles are on fixed value resistors and on variable resistors that are manipulated by human intervention. Check them out if you missed them. And let us know in the comments of any resistors that we missed along the way or of anything you’d like to add.

Filed under: Featured, Interest, Original Art, slider

Ghetto Ribbon Connector

อังคาร, 09/27/2016 - 18:01

[Marcel] was trying to shoehorn a few new parts into his trusty Nexus 5 phone. If you’ve ever opened one of these little marvels up, you know that there’s not much room under the hood to work with. Pulling out some unnecessary parts (like the headphone jack) buys some space, but then how to wire it all up?

[Marcel] needed a multi-wire connector that’s as thin as possible, but he wasn’t going to go the order-Kapton-flex route. Oh no! He built one himself from masking tape and the strands from a stranded wire. Watch the video how-to if that alone isn’t enough instruction.

Since the wires are uninsulated, [Marcel] is a bit careful to separate each strand with tape. While [Marcel] makes a straight connector in the video, we could easily imagine making a pre-formed cable just like the mass-produced flex cables that come with the phone. All in all, this is a great trick to have up your sleeve when space is at a premium.

We’re sure that some of you wire-wrap gurus would be tempted to just let your wires hang loose, but can you imagine how the insides of a phone would look with just a few additional peripherals?

Filed under: Cellphone Hacks, misc hacks

Putting Sand, Water, and Metal into A 3D Print

อังคาร, 09/27/2016 - 15:01

[Adam] over at Makefast Workshop writes about some of the tests they’ve been running on their 3D printer. They experimented with pausing a 3D print midway and inserting various materials into the print. In this case, sand, water, and metal BBs.

The first experiment was a mixture of salt and water used to make a can chiller for soda or beer (the blue thing in the upper right). It took some experimentation to get a print that didn’t leak and was strong. For example, if the water was too cold the print could come off the plate or delaminate. If there was too much water it would splash up while the printer was running and cause bad layer adhesion.

They used what they learned to build on their next experiment, which was filling the print with sand to give it more heft. This is actually a common manufacturing process — for instance, hollow-handled cutlery often has clay, sand, or cement for heft. They eventually found that they had to preheat the sand to get the results they wanted and managed to produce a fairly passable maraca.

The final experiment was a variation on the popular ball bearing prints. Rather than printing plastic balls they designed the print to be paused midway and then placed warmed copper BBs in the print. The printer finished its work and then they spun the BB. It worked pretty well! All in all an interesting read.

Filed under: 3d Printer hacks