Wednesday, August 31
The Evolution of a DIY Circuit Board Plotter
In this three part video series we watch [Dirk Herrendoerfer] go from scraps to a nice 3D printed assembly as he iterates through the design of a pen plotter for making circuit boards.
[dana] mentioned [Dirk]’s work in the comments of this post which describes a different process. Many permanent markers stick to copper well enough to last through the chemical etching process. While hand drawing definitely produces some cool, organic-looking boards, for sharp lines and SMDs it gets a bit harder; to the point where it becomes advisable to just let a robot do it.
Of course, [Dirk] was aware of this fact of life. He just didn’t have a robot on hand. He did have some electronic detritus, fishing line, an Arduino, scrap wood, brass tubes, and determination. The first version‘s frame consisted of wooden blocks set on their ends with holes drilled to accept brass rods. The carriage was protoboard and hot glue. Slightly larger brass tubing served as bushings and guide. As primitive as it was the plotter performed admirably, albeit slowly.
The second version was a mechanical improvement over the first, but largely the same. The software got a nice improvement. It worked better and had some speed to it.
The latest version has some fancy software upgrades; such as acceleration. The frame has gone from random bits of shop trash to a nicely refined 3D printed assembly. Even the steppers have been changed to the popular 28BYJ-48 series. All the files, software and hardware, are available on GitHub. The three videos are viewable after the break. It’s a great example of what a good hacker can put together for practically no money.
Filed under: Arduino Hacks, cnc hacks
Simple Arduino-Controlled, No-Pump Plant Watering
The post Simple Arduino-Controlled, No-Pump Plant Watering appeared first on Make: DIY Projects and Ideas for Makers.
New X-Carve CNC Router Bulks Up for Advanced Usage
The post New X-Carve CNC Router Bulks Up for Advanced Usage appeared first on Make: DIY Projects and Ideas for Makers.
Circuit Design? Spread the Joy
Accountants and MBAs use spreadsheets to play “what if” scenarios with business and financial data. Can you do the same thing with electronic circuits? The answer–perhaps not surprisingly–is yes.
Consider this simple common emitter amplifier (I modeled it in PartSim, if you’d like to open it):
In this particular case, there are several key design parameters. The beta of the transistor (current gain) is 220. The amplifier has an overall voltage gain of about 3 (30/10). I say about, because unless the transistor is ideal, it won’t be quite that. The supply voltage (Vcc) is 12 volts and I wanted the collector voltage (VC) to idle at 6V to allow the maximum possible positive and negative swing. I wanted the collector current (IC) to be 200mA.
Design by Math
So how do you select the values of the resistors? Start with R3 at the collector. I specified that VC=6V and Vcc=12 V so R3 has to drop 6 V. If VC had been, say, 9 V then the drop would be 12-9 or 3 V. I also said that the collector current, IC, had to be 0.2 A. Ohms law, then, says R3= 6/0.2 = 30 ohms.
The gain in this configuration is going to be R3/R4. So if the gain is 3 and R3 is 30, it stands to reason that R4 is 10. The current through R4 is almost the same as IC. It is actually related by the alpha of the transistor which is related to the beta. In a transistor like this, the alpha will be nearly 1.0. That means the emitter current will be equal to slightly more than the collector current. For a quick calculation, let’s assume they are the same so the voltage at the emitter is going to be 0.2 times 110 or 2 V.
The voltage at the base, then, needs to be about 0.7 higher or 2.7 V. Because the transistor model is accurate and it models a real transistor, I actually want to set the base voltage to about 0.8 V higher than the emitter and that’s 2.8 V. The base will look like the emitter resistor times beta in ohms (2220 ohms). So the voltage divider of R1 and R2 really has 2200 ohms in parallel with R2. To get the 12 V knocked down to 2.8 V needs R1=202 ohms and R2 to about 64 ohms. That’s it! You now know all the values and PartSim (or another circuit simulation tool) will show that it works. The 1 kHz signal is just for testing and you can see you get roughly a gain of 3 from input to output (along with a 180 degree phase shift):
Spread the Joy
While those steps aren’t very complex, it is tedious. Why not use a spreadsheet (download amp.xlsx from GitHub) to capture the algorithm? Then you can easily make changes and see the results instantly. Here’s an example:
What happens if you change the IC to 0.1 A? Or the gain to 5? Or the input voltage to 24 V?
There are two cells that you probably won’t change much, so they aren’t under inputs, but they do affect the overall design. The first is the Vbe drop. For a normal silicon transistor, this should be about 0.6 or 0.7 volts, dependant on temperature. If the real circuit or an accurate simulation shows a different voltage drop between base and emitter (for example, the base is at 2.8 V and the emitter is at 2 V), use that difference (0.8) in the parameter and you’ll get a better result.
The second cell is the current in the voltage divider (R1 and R2). The total current through R1 is equal to the current through R2 and the base of the transistor. The base looks (more or less) like the emitter resistor multiplied by the beta of the transistor (which isn’t a very stable parameter). In theory, you could use a lot of different values of the voltage divider resistors to get the correct ratio. The spreadsheet assumes that the total current will be a fixed multiple of the expected base current. If you set this multiplier too low, you’ll get a negative resistance, so you’ll have to raise it.
In general, if you set the total current to, say, four times the base current, then R2 will get three times the base current through it. A reasonable value is 10 which ensures that changes in the base current won’t affect the divider output very much.
Of course, the spreadsheet won’t pick standard resistance values. That’s fine for simulation, but if you are really going to build, you might want to get close values. For example, to use a 47 ohm collector resistor, you could adjust the quiescent voltage or the collector current. For example, try the example with a collector current of 0.127. That results in values of 47 ohms and 16 ohms, both standard 5% resistors. For the dividers, you can play with the current multiplier. Continuing on the example, setting it to 11 puts the divider in range of a 1.5K resistor and a 510 ohm resistor, both standard values. Remember, device parameters will vary along with part tolerances, so getting close is good enough (and if it isn’t, then you have a problem anyway because of variations due to the manufacturing of the transistor, temperature, and other effects).
Speaking of tolerances, it is easy to look at the effect of tolerance ranges using the spreadsheet. With a little work you could even repeat the math on a single spreadsheet to catch all the end cases.
Solve Your Problem
Many spreadsheet programs can also solve optimization problems. Next time, I’ll show you how you can use that in conjunction with models of your circuit to easily find component values.
Filed under: how-to
Big Brother and Others Are Watching Your Car
We are all (hopefully) aware that we can be watched while we’re online. Our clicks are all trackable to some extent, whether it’s our country’s government or an advertiser. What isn’t as obvious, though, is that it’s just as easy to track our movements in real life. [Saulius] was able to prove this concept by using optical character recognition to track the license plate numbers of passing cars half a kilometer away.
To achieve such long distances (and still have clear and reliable data to work with) [Saulius] paired a 70-300 mm telephoto lens with a compact USB camera. All of the gear was set up on an overpass and the camera was aimed at cars coming around a corner of a highway. As soon as the cars enter the frame, the USB camera feeds the information to a laptop running openALPR which is able to process and record license plate data.
The build is pretty impressive, but [Saulius] notes that it isn’t the ideal setup for processing a large amount of information at once because of the demands made on the laptop. With this equipment, monitoring a parking lot would be a more feasible situation. Still, with even this level of capability available to anyone with the cash, imagine what someone could do with the resources of a national government. They might even have long distance laser night vision!
Filed under: digital cameras hacks
Freeze Crystal Clear Ice Balls for Cocktails
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15 Ingredients for Building the Perfect Food Truck
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Can a Juvenile Hall Makerspace Help Teens Suspend Their Disbelief?
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Makerspace Organizers Convene at The White House
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Maker Spotlight: Cristiana Felgueiras
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Build a Tiny (Unstable) Bugging Device
We don’t know who the [amgworkshop] wanted to listen in on, but they apparently went searching for a small FM wireless transmitter. There’s plenty of circuits around, but they wanted something smaller. The original circuit had a variable capacitor to tune the output frequency. The new design uses a fixed capacitor and a spring for an antenna. You can see the build steps in the video below, but don’t expect a lot of frequency stability or fidelity out of a single transistor transmitter.
The parts list is minimal. In addition to a coin cell holder (which serves as the construction base), you need a transistor, two resistors, three capacitors, a homemade inductor (very easy to make with some wire and a drill bit), and an electret microphone. Of course, you need a battery, too. The whole thing is potted with hot glue.
If you want a better circuit (and longer battery life) you might look at [Angelo’s] similar build. Not quite as tiny, though. There’s no shortage of other examples out there, many using different construction methods.
Filed under: radio hacks
Monitor Light Pollution with Photodiodes
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3D-Printed Raspberry Pi Skycam for Drone-Free Aerial Video
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Build a Persistence-of-Vision LED Globe
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Amazon Dash Button Finds Your Phone
This scene replays quite often in our house: my wife has misplaced her cell phone so she asks me to call her. But where did I leave my cell phone? And the race is on! Who will find their phone first to call the other?
[Zapta] solves this problem with his Phone Finder. The system comes in two parts: a base station with WiFi that’s also connected to the house’s phone line, and an arbitrary number of Amazon Dash buttons that trigger dialing commands.
[Zapta] presses a Dash button, which connects over WiFi to the base station. The base station recognizes the MAC address of the button, looks up and dials the corresponding missing cell phone. This solves the need-a-phone-to-find-a-phone problem very neatly, and since Dash buttons are dirt cheap they can be scattered liberally around the house. They’re clearly marked “his” and “hers” suggesting a similar domestic dynamic.
If we were implementing the base station from scratch, we’d probably try to figure out how a single ESP8266 could do all of the heavy lifting, but browsing through [Zapta]’s GitHub and the included circuit diagram (PDF) demystifies the phone-line interface.
In the early days of cordless phones, we used to joke that a solution to losing them would be to attach a string and tie them to the wall. (Luddites!) We’re glad to see [Zapta] take this project in the opposite direction — using technological overkill to solve the unintended problems that arise from technological progress.
Filed under: Cellphone Hacks
Pan and Tilt with Dual Controllers
It wasn’t long ago that faced with a controller project, you might shop for something with just the right features and try to minimize the cost. These days, if you are just doing a one-off, it might be just as easy to throw commodity hardware at it. After all, a Raspberry Pi costs less than a nice meal and it is more powerful than a full PC would have been not long ago.
When [Joe Coburn] wanted to make a pan and tilt webcam he didn’t try to find a minimal configuration. He just threw a Raspberry Pi in for interfacing to the Internet and an Arduino in to control two RC servo motors. A zip tie holds the servos together and potentially the web cam, too.
You can see the result in the video below. It is a simple matter to set up the camera with the Pi, send some commands to the Arduino and hook up to the Internet.
The serial protocol for the Arduino is simple: The Pi sends a numeric position followed by a P (for pan) or T (for tilt) at 9600 baud. A web server and some Python handle the interface to the Internet and the human.
We’ve certainly seen our share of similar projects. Some of them have been a bit larger.
Filed under: Arduino Hacks, Raspberry Pi
High-end Headphones Fixed with High-end CNC Machine
Warranty? We don’t need no stinking warranty! We’re hackers, and if you have access to a multi-million dollar CNC machine and 3D CAM software, you mill your own headphone replacement parts rather than accept a free handout from a manufacturer.
The headphones in question, Grado SR325s, are hand-built, high-end audiophile headphones, but [Huibert van Egmond] found that the gimbal holding the cups to the headband were loosening and falling out. He replicated the design of the original gimbal in CAM, generated the numeric code, and let his enormous Bridgeport milling machine loose on a big block of aluminum. The part was drilled and tapped on a small knee-mill, cut free from the backing material on a lathe, and bead-blasted to remove milling marks. A quick coat of spray paint – we’d have preferred powder coating or anodization – and the part was ready to go back on the headphones.
Sure, it’s overkill, but when you’ve got the tools, why not? And even a DIY CNC router could probably turn out a part like this – a lot slower, to be sure, but it’s still plausible.
Filed under: misc hacks
Tuesday, August 30
Tricking Duck Hunt to See A Modern LCD TV as CRT
A must-have peripheral for games consoles of the 1980s and 1990s was the light gun. A lens and photo cell mounted in a gun-like plastic case, the console could calculate where on the screen it was pointing when its trigger was pressed by flashing the screen white and sensing the timing at which the on-screen flying spot triggered the photo cell.
Unfortunately light gun games hail from the era of CRT TVs, they do not work with modern LCDs as my colleague [Will Sweatman] eloquently illustrated late last year. Whereas a CRT displayed the dot on its screen in perfect synchronization with the console output, an LCD captures a whole frame, processes it and displays it in one go. All timing is lost, and the console can no longer sense position.
[Charlie] has attacked this problem with some more recent technology and a bit of lateral thinking, and has successfully brought light gun games back to life. He senses where the gun is pointing using a Wiimote with its sensor bar on top of the TV through a Raspberry Pi, and feeds the positional information to an Arduino. He then takes the video signal from the console and strips out its sync pulses which also go to the Arduino. Knowing both position and timing, the Arduino can then flash a white LED stuck to the end of the light gun barrel at the exact moment that part of the CRT would have been lit up, and as far as the game is concerned it has received the input it is expecting.
He explains the timing problem and his solution in the video below the break. He then shows us gameplay on a wide variety of consoles from the era using the device. More information and his code can be found on his GitHub repository.
We’ve featured [Charlie]’s work in the retro gaming field before, with his HDMI mod for a Neo Geo MVS. Console light guns have made a lot of appearances on these pages, a recent one was this video synthesiser but it’s this burning laser mod that most children of the 1980s would have given anything to own.
Filed under: nintendo hacks, nintendo wii hacks
Four Of Our Favorite Hardware Talks
The Hackaday SuperConference is the greatest gathering of hardware hackers on the planet. Last year at the SuperCon, we saw talks on building systems from scratch, creating new and interesting uses for technology, and bringing those electronic bits to market. What are we talking about? Here are four of the best talks from last year’s Hackaday SuperConference:
[Shanni Prutchi] is an ECE student at Rowan University, and has already published papers on radio astronomy and metrology. Her provides an overview of building her own source of quantum entangled photons and how these photons can be used. Quantum Key Distribution is possible on a small-scale, and not just in the realm of university optics labs.
The best conference talk I’ve ever seen came from [sprite_tm] last year. He created a Matrix of Tamagotchis. Tamagotchis — those loveable digital pets living in an embedded system — are really just computer code, after all, and after reverse engineering the Tamagotchi itself, he emulated several on a server, giving them the ability to communicate with each other and even have children. The best part? [sprite]’s Matrix isn’t a weird almost-perpetual motion machine demanded by studio execs.
Building one of something is easy, but building a thousand is a million times harder. This is the problem of manufacturing electronics, and no one covered it better than [Zach Fredin] and his talk on pilot scale production. The first step of manufacturing is always the hardest, and for [Zach] that was pilot scale production. In the talk, [Zack] gave a few tips like always springing for a stencil, where to get boards manufactured, and the ins and outs of EDA software.
Haptic interfaces are the next frontier. Eventually, we’re all going to be wearing our computers, and [Neil Movva]’s talk on haptic technology was the state of the art in interfaces based on touch. He had some hardware to demo at the conference, demonstrating how different vibrations can feel like different textures. It’s weird, and at the forefront of technology.
We Want You To Speak At This Year’s Supercon
The 2016 Hackaday Superconference is happening on November 5th and 6th, in Pasadena, California. View all the talks from 2015, get excited, and get your proposal submitted!
Filed under: cons, Hackaday Columns, roundup
Shell Game
A lot of us spend a lot of time switching between Windows and Linux. Now that platforms like the Raspberry Pi are popular, that number is probably increasing every day. While I run Linux on nearly everything I own (with the exception of a laptop), my work computers mostly run Windows. The laptop is on Windows, too, because I got tired of trying to get all the fancy rotation sensors and pen features working properly under Linux.
What I hate most about Windows is how hard is it to see what’s going on under the hood. My HP laptop works with a cheap Dell active stylus. Sort of. It is great except around the screen edges where it goes wild. Calibration never works. On Linux, I could drill down to the lowest levels of the OS if I were so inclined. With Windows, it is just tough.
War is Shell
One place where Linux always used to have an advantage over DOS and Windows was the shell. There are lots of variations available under Linux, but bash seems to be the current pick for most people. If you want more power, you can move to some alternatives, but even bash is pretty powerful if you learn how to use it and have the right external programs (if you don’t believe it, check out this web server).
In the old DOS days, some of us went to 4DOS which was nice, but no bash (and apparently morphed into the Windows Take Command Console software. I’ve seen a few people use things like Rexx as a shell under DOS or Windows, but it has always been a small minority.
Windows Power
Microsoft finally addressed the shortcomings of its default command interpreter, first introducing Windows Scripting Host to allow Javascript and VBScript batch files. Eventually, this was supplanted by Monad which later became known as the Windows PowerShell.
In addition to running programs, the PowerShell can use functions and cmdlets (programs made to interact with the shell). While it isn’t compatible with a traditional Linux shell, it has similar powers and many people–especially system administrators–make heavy use of it to automate tasks.
Shell Shock
Two things have recently happened that surprised me. First, Microsoft made bash available (and other Linux executables) for Windows 10 as a native application (you can find the detailed install directions online). The surprise isn’t that this is possible. I’ve used Cygwin and UWIN to have a very full-featured Linux environment under Windows for years (and did the same with MKS under DOS). The surprise was that Microsoft would “cross the streams” and officially support a Linux/Unix tool on Windows. Sure, NT used to have a crippled POSIX subsystem, but it wasn’t practical. This appears to be a genuine attempt to put the shell on Windows (which, again, is only remarkable because it is Microsoft doing it).
The second piece of news that surprised me is that you can now get PowerShell for Linux or OS/X. I’m not sure how many Linux users will rush out for a .NET tool, but it is one more way to make the systems more alike which is nice when you use both.
Decisions, Decisions…
So now you have several options for using Linux and Windows without going crazy switching between the two:
- Run Linux and put Windows in a virtual machine
- Run Windows and put Linux in a virtual machine
- Use bash everywhere (using Cygwin or the Microsoft product)
- Use PowerShell everywhere
If you just can’t stand to take software from Microsoft, you could check out PASH, which is essentially a rewrite of PowerShell using Mono. I’m not sure how much momentum it will retain now that Microsoft is supporting something so similar.
If you do want to learn more about PowerShell, the Wikipedia article on it has a nice table that relates PowerShell to cmd.exe to Linux shell. There’s also a video, you can watch below.
Thanks to [rogeorge] for the tip about PowerShell.
Filed under: Hackaday Columns, rants
Citizen Scientist Radio Astronomy (and More): No Hardware Required
We sometimes look back fondly on the old days where you could–it seems–pretty easily invent or discover something new. It probably didn’t seem so easy then, but there was a time when working out how to make a voltage divider or a capacitor was a big deal. Today–with a few notable exceptions–big discoveries require big science and big equipment and, of course, big budgets. This probably isn’t unique to our field, either. After all, [Clyde Tombaugh] discovered Pluto with a 13-inch telescope. But that was in 1930. Today, it would be fairly hard to find something new with a telescope of that size.
However, there are ways you can contribute to large-scale research. It is old news that projects let you share your computers with SETI and protein folding experiments. But that isn’t as satisfying as doing something personally. That’s where Zooniverse comes in. They host a variety of scientific projects that collect lots of data and they need the best computers in the world to crunch the data. In case you haven’t noticed, the best computers in the world are still human brains (at least, for the moment).
Their latest project is Radio Meteor Zoo. The data source for this project is BRAMS (Belgian Radio Meteor Stations). The network produces a huge amount of readings every day showing meteor echoes. Detecting shapes and trends in the data is a difficult task for computers, especially during peak activity such as during meteor showers. However, it is easy enough for humans.
There are many other Zooniverse projects if that one doesn’t fit your fancy. You can search for comets and supernova, study animal behavior, help transcribe documents from Shakespeare’s contemporaries, or study weather patterns from old ship’s logs. You won’t get paid (or charged, either) but you’ll be helping science and maybe learn something, too. The typical project gives you some form of training and relies on many people evaluating the same data to ensure the quality of the results is good.
You can find a video about an older Zooniverse project, below. In that one, you classify shapes of distant galaxies. Don’t get us wrong, though. There’s still independent citizen scientists out there. We have even covered a few of the more notable specimens. These are great projects to spur the interest of a budding young scientist, or rekindle the scientific spirit in us old timers. Would probably make a fair classroom project, too.
Filed under: news
Dealmaster: Get 30 percent off the X1 Carbon and all ThinkPads
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Maker Faire San Diego: Calling All Early Birds and Makers
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Kits and Community Lead to Grit
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Programmable LED Handbag for Any Occasion
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Maker Spotlight: Hannah Wides
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Impressive Junkyard CNC Made From Fancy Garbage
We’ll just come out and say it, [reboots] has friends with nice garbage. Sure, some of us have friends who are desperately trying to, “gift,” us a CRT monitor, hope dropping like a rock into their stomach when they realize they can’t escape the recycling fee. [reboots] has friends who buy other people’s poorly thought out CNC projects and then gift him with the parts.
After dismantling the contraption he found himself with nice US and Japanese made linear motion components. However, he needed a CNC controller to drive it all. So he helped another friend clean out their garage and came away with a FlashCut CNC controller.
Now that he had a controller and the motion components whirring nicely, he really needed a frame to put it all in. We like to imagine that he was at a friend’s barbeque having a beer. In one corner of the yard was an entire Boeing 747. A mouldering scanning electron microscope with a tattered and faded blue tarp barely covering its delicate instrumentation sat in another corner. Countless tech treasures were scattered about in various states. It was then that he spotted a rusting gamma ray spectrometer in the corner that just happened to have the perfect, rigid, gantry frame for his CNC machine.
Of course, his friend obliged and gladly gave up the spectrometer. Now it was time to put all together. The gantry was set on a scavenged institutional door. The linear motion frames were bolted in place. Quite a few components had to be made, naturally, of scrap materials.
Even routers that allow you to adjust the speed (a fairly common feature on new models) generally don’t actually regulate that speed. So, you end up with a handful of speed settings which aren’t even predictable under load. Furthermore, they usually rely on high RPMs to do their work. For those reasons, handheld woodworking routers aren’t the best choice for a mill that you intend to cut metal with.
[reboots] noticed this problem while building this machine and came up with an inexpensive way to build a speed-controlled spindle. His design uses a brushless DC motor, controlled through a hobby ESC (electronic speed control), which uses a belt to drive the spindle. The spindle itself is mounted using skateboard bearings, and ends in an E11 collet (suitable for light machining in aluminum).
With the ESC providing control of the brushless motor, he’s able to directly control the spindle speed via software. This means that spindle speeds can be changed with G-code, allowing for optimized feeds and speeds for different operations. The belt-drive increases torque while separating the motor from the spindle, which should keep things cool, and reduce rotating mass on the spindle itself. Now all [reboots] needs to do is add a DIY tool changer!
Filed under: cnc hacks
Fixing the Ampere: Redefining the SI Unit
We all know that it’s not the volts that kill you, it’s the amps. But exactly how many electrons per second are there in an amp? It turns out that nobody really knows. But according to a press release from the US National Institute of Standards and Technology (NIST), that’s all going to change in 2018.
The amp is a “metrological embarrassment” because it’s not defined in terms of any physical constants. Worse, it’s not even potentially measurable, being the “constant current which, if maintained in two straight parallel conductors of infinite length, of negligible circular cross-section, and placed 1 meter apart in vacuum, would produce between these conductors a force equal to 2 x 10–7 newton per meter of length.” You can’t just order a spool of infinite length and negligible cross-section wire and have it express shipped.
So to quantify the exact number of electrons per second in an amp, the folks at NIST need an electron counter. This device turns out to be a super-cooled, quantum mechanical gate that closes itself once an electron has passed through. Repeatedly re-opening one of these at gigahertz still provides around a picoamp. Current (tee-hee) research is focused on making practical devices that push a bit more juice. Even then, it’s likely that they’ll need to gang 100 of these gates to get even a single microamp. But when they do, they’ll know how many electrons per second have passed through to a few tens of parts per billion. Not too shabby.
We had no idea that the amp was indirectly defined, but now that we do, we’re looking forward to a better standard. Thanks, NIST!
Thanks [CBGB123B] for the tip!
Filed under: news
Really Easy Jacob’s Ladder
There was a time when making a high voltage project like a Jacob’s ladder took time to build or scrounge some kind of high voltage circuit. The neon sign transformer, Marx generator, or voltage multiplier was the hard part of the project. But nowadays you can get cheap high voltage modules that are quite inexpensive. [PaulGetson] picked up one for under $20 and turned it into a quick and easy Jacob’s ladder.
Honestly, once you have high voltage, making a Jacob’s ladder is pretty simple. [Paul] used a cheap plastic box, some coat hanger wire, and some stainless steel bolts.
If you haven’t seen a ladder before, the theory is pretty simple. The high voltage ionizes the air between the two electrodes. The ionized air gets hot and since hot air rises, the spark rises with it, and the electrodes can get further and further apart. Once the spark rises above the electrodes, the process starts over again. You can see these in many old movies to signify some sort of mysterious scientific equipment.
We have covered Jacob’s ladders before, but few of them as simple as this. We’ve even seen simulated ladders, in case you are too timid to work with the high voltage.
Filed under: classic hacks
DIY Electric Pennyboard Can Hit 40Km/h!!
Home-made transportation is a thriving area for makers to flex their skills. Looking to shorten their university commute, [doublecloverleaf] modded his penny board by adding a motor that can have him zipping along at 40 Km/h!
The electric motor is mounted to the rear truck and delivers power to the wheel gear using a HTD 5 m pulley belt. Finding the deck too flexible to mount the battery pack under, [doublecloverleaf] strengthened it with a pair of carbon-fiber tubes bracketed on the underside. A few custom PCB boards connect ten 5 Ah LiPo battery cells in series to create two, five-cell packs which are kept safe by a thick housing mounted between the board’s trucks. [doublecloverleaf] calculates that they could make up to a 15 km trip on a single charge.
Thinking ahead, [doublecloverleaf] opted to use a DB25 port for charging — 9 pins for voltage balancing between cells within each battery, and ten more (five positive, five negative, in parallel) for charging at 5 A. A USB port allows him to tweak the VESC motor controller — this adds, among other useful features, regenerative braking!
A slightly modified RC car remote controls the motor — simply pull on the trigger to accelerate, and push to reverse and engage the regenerative breaking. It’s currently set to 80% of the motor’s max RPM at 40 A to preserve both the board and the rider’s health. Any faster, and they’d have to think about challenging the land speed record for electric skateboards.
Filed under: transportation hacks
Monday, August 29
Musical Proximity Detection Pet Bowls
An essential skill for a maker is the ability to improvise or re-purpose existing materials into new parts. Sometimes, one needn’t make many modifications to create something new, as is the case with [Robin Sterling] and his musical pet bowl.
Originally, it was a sealed pet bowl that opened when the proximity sensors detected an approaching pet. Having helped design the bowl, [Sterling] had a bit of an advantage when he decided to convert it into a theremin/light harp-esque instrument for the company BBQ. He routed the PWM outputs from each of the three proximity sensors (in each of the three bowls) to a small guitar amp, adjusting each sensor’s output to a different frequency. Despite the short amount of time [Sterling] had to practice, it works fairly well!
[Sterling] adds that the bowl’s firmware knows which proximity sensor is being triggered, making this an easy mod indeed. From musical bowls to refurbishing a paper-tape music box, or an entire musical ensemble with a constantly changing melody, the unity of maker and musician never ceases to amaze.
Filed under: misc hacks
It’s almost impossible to correct scientific papers once they are published
The classic model of scientific progress is that the field advances when new findings contradict or supersede old ones. But a new study reveals that this process isn't working today—at least, not in scientific journals, where most data is shared with colleagues. Indeed, the researchers found that "rebuttals scarcely alter scientific perceptions about the original papers."
For the study, a group of researchers looked at the citation rates on seven marine biology papers about fisheries. Citation rates are often used as a proxy for the "importance" of a scientific paper, with the notion that the more a paper is cited, the more influential it is. Each paper had been the subject of a rebuttal, also published in a scientific journal. The researchers wanted to know whether these rebuttals affected citation levels on the original papers—and, perhaps more importantly, whether they convinced people to question the interpretation of data in the original papers.
It turns out that rebuttals don't seem to affect the scientific community's understanding of the original papers in any way. "The original articles were cited 17 times more frequently than the rebuttals, an order of magnitude difference that overwhelms other factors," write the study authors in Ecosphere. "Our test score results emphasize that rebuttals have little influence: even the rare few authors who happened upon the rebuttals were influenced only enough to move from whole-hearted support of the original article (a score of five) to neutrality (a score of three), despite the fact that all of the rebuttals argue that the interpretations of data in the originals were incorrect. Astonishingly, 8 percent of the papers that cited a rebuttal actually suggested that the rebuttal supported the claims of the original article, an observation which may give pause to those contemplating writing a rebuttal in the future."
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Building Better Tube Amps With Heathkit Parts
[Justin] had been trying to find a good tube amp for years, but all the best examples were either expensive or a complete basket case. Instead of buying a vintage stereo tube amp, he decided to build his own using the guts of a Heathkit AA-100, a popular tube amp from the 60s and 70s that doesn’t have a great reputation for sound quality.
This project was based on an earlier project from a decade ago that replicated the very popular Dynaco ST-70 tube amp from parts taken from the Heathkit AA-100. The schematic for this conversion was readily available on the usual tube head message boards, and a few PCBs were available for the input stage.
With the schematic in hand, the next thing for [Justin] to do was get a nice enclosure. High quality tube amps are valued as much for their appearance as they are for their sound quality, and after giving his father-in-law a few sketches, a cherry hardwood chassis stained in a beautiful golden brown appeared on [Justin]’s workbench.
The big iron for this new tube amp was taken directly from the old Heathkit, and a few hours in front of a mill netted [Justin] a chassis panel drilled out for the transformers and tube sockets. The rest of the project was a bit of assembly, point-to-point wiring, and wire management giving [Justin] a fantastic amplifier that will last for another fifty years until someone decides to reuse the transformers.
Filed under: classic hacks
Making the Future in Cambodia
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Construct a CNC Plasma Cutter for $3000
The post Construct a CNC Plasma Cutter for $3000 appeared first on Make: DIY Projects and Ideas for Makers.
Maker Spotlight: Jen Herchenroeder
The post Maker Spotlight: Jen Herchenroeder appeared first on Make: DIY Projects and Ideas for Makers.
Let’s Put A Hackerspace In Prison
The Hack42 Hackerspace in Arnhem, Netherlands is one of the best hackerspaces we’ve ever seen. After taking over a decommissioned military base, the Hack42 crew has filled a compound rimmed with razor wire with eclectic gizmos, tools, and a community that keeps growing the space. At this year’s EMF camp, Hack42 member [jos] laid out his plan to found the ultimate Hackerspace. He’s going to put a hackerspace in prison to create the ultimate hacker village, a monument to technomancy, and an anti-panopticon panopticon.
[jos] recently noticed a very large, very old prison — currently used to house refugees — went up for sale. This prison, located in downtown Arnhem, Netherlands is a panopticon, a concept for prisons popularized in the 1800s, with most designs based on a circular structure with prison cells along the diameter and a guard house in the center. This gigantic building is 55 meters (180 feet) in diameter, and 46 meters (150 feet) tall at its highest point. This gigantic prison dome could contain the White House inside its walls, a few blue whales, and could almost fit a space shuttle stack under the dome (the orbiter itself would fit just fine if there were a door).
The ambitious vision for this prison-come-hackerspace is a permanent venue not unlike other hackercamps where hackers can stay for weeks or months to build a project, a venue for like-minded people to meet up, and a place for students to do graduation projects under the wings of academic leadership. A community is one thing, but this former prison would also be the largest hackerspace by enclosed volume, opening it up to some very cool, very large builds. Inter-office quadcopter mail was mentioned in the talk.
[jos] is looking for comments, ideas, and remarks via this Google form to, “convince the money-people to fork over the funds.” If you’ve ever wanted to contribute to something big, this is your chance.
Filed under: Hackerspaces
