Hackaday

Syndicate content Hackaday
Fresh hacks every day
ถูกปรับปรุง 4 hours 50 min ก่อน

Get Inside a TCXO Clock Chip

พุธ, 08/09/2017 - 22:05

[Pete] wondered how real-time clock modules could be selling on eBay for $1.50 when the main component, the Maxim DS3231 RTC/TCXO chip, cost him more like $4 apiece. Could the cheap modules contain counterfeit chips?

Well, sure they could. But in this case, they didn’t, and [Pete] has the die shots to prove it. He started off by clipping the SOIC leads rather than desoldering — he’s not going to be reusing this chip after he’s cut it in half. Next was a stage of embrittling the case by heating it up with a lighter and dunking it in water. Then he went at it with sandpaper.

It’s cool. You can see the watch crystal inside, and all of the circuitry. The DS3231 includes a TCXO — temperature-corrected crystal oscillator — and it seems to have a bank of capacitors that it connects and disconnects depending on the chip’s temperature to keep the oscillator running at the right speed. [Pete] used one in an offline situation, and it only lost sixteen seconds over a year, so we’d say that they work fine.

If you’d like to know more about how crystals are used to keep time, check out [Jenny]’s excellent article. And if sixteen second per year is way too much for you, tune up your rubidium standard and welcome to the world of the time nuts.


Filed under: hardware

The Sensors Automating Your Commute

พุธ, 08/09/2017 - 21:01

In a bout of frustration I recently realized that the roads have all updated — most people have no idea how — and this sometimes hurts the flow of traffic. This realization happened when an unfortunate person stopped in a left turn lane well before the stop line. The vehicle didn’t trigger the sensor, so cycle after cycle went by and the traffic system never gave the left turn lane a green light, thinking the lane was unoccupied. Had the driver known about this the world would have been a better place. The first step in intelligent automation is sensing, and there are a variety of methods used to sense traffic’s flow.

Many stoplights run on timers that do the same thing on a loop. First they were electromechanically controlled, and now they are digital. When sensing technology arrived, it made systems intelligent enough to adjust the cycle based on traffic. Nobody in the left turn lane? Don’t bother with a left turn signal in the cycle, and it shaves some seconds off and allows for smoother traffic flow.

Inductive Loops

You’ve probably seen them, but never considered what they are or how they work. Most often at stoplights, but sometimes before the stoplight, there will be a square in the pavement. This is where the road was cut, and a loop of wire inserted, then covered. The loop of wire is an inductor, and a large piece of metal next to it will induce eddy currents, which are measured by the system. If the piece of metal doesn’t generate enough eddy currents (say from a bicycle or motorcycle), the system will not recognize the presence of anything. It also means that if you drive past the stop line so that your car is no longer over the loop, then you may not be detected and the traffic control logic will skip you in the next cycle.

The takeaway with inductive loops is that if you go through a full cycle of lights and don’t get a turn, it’s likely because you’re not triggering the sensor.

Look for traffic loops at the stop lines of intersections and sometimes set back (on the East/West road here), or on highways.

If the loops are a ways back from the light, they might be used to trigger the light to start turning for you so you don’t need to stop. This is useful when the light doesn’t cycle based on time but instead defaults to green in one direction, and you are approaching from the other direction. If the system doesn’t see any traffic on the normally green side, it will change the light so that you can coast through without stopping, then change back to the default.

If you see two loops in a single lane, usually on a highway, and one is right after the other, then you’re looking at something that measures speed of a vehicle driving over it. This is usually on the highway or heavily trafficked roads at higher speed, and can be used for general data collection, or to feed the signs that say “8 minutes to I-80”. If the hardware and firmware are good, the induction can be measured well enough that the type of vehicle and number of axles can be calculated. A semi traveling over a loop would increase the baseline, with a short spike at each axle.

Radar

RTMS installed in New York [via InvisibleBoxes.info]These are small units on traffic lights that use microwave radar to detect the presence and speed of moving vehicles. The radar can detect the vehicle approaching the stop line, and when tied into the traffic signal system, knows when a vehicle is passing through a red light and can generate a ticket. This is controversial because it conflicts with the generally held belief that “green means go, red means stop, and yellow means go really fast.” Perhaps not surprisingly, red light tickets do reduce certain kinds of intersection accidents, but it turns out they are also linked to increases in rear-end collisions.

Of course issuing tickets isn’t the only radar application you’ll find in the traffic technology arsenal. Remote Traffic Microwave Sensing (RTMS) is a technology used to go beyond what inductive loop sensors can do. RTMS is usually positioned at the side of the road, sensing perpendicular to the movement of traffic. Available sensors like the Sx-300 boast capabilities like “per-lane presence as well as volume, occupancy, speed and classification information in up to 12 user-defined detection zones”. The image shown here is an RTSM G4/K4 seen installed on a New York City street. Thanks to the FCC filing you can page through the user manual which is quite interesting.

Infrared

Far Infrared Vehicle Detector [via Sumitomo Electric]Passive infrared sensors can measure the heat signatures of vehicles and use that to detect presence and speed. They have some limitations, though. Specifically, they don’t like moisture in the atmosphere blocking them. In heavy rain or snow, the sensors may only see the water and not the vehicles, so it’s possible to be undetectable when sitting right in front of an infrared sensor. It’s also possible (through poor engineering) to have an infrared sensor that is facing in exactly the wrong direction at either sunset or sunrise during certain parts of the year, rendering it useless.

Cameras

You’ll see cameras on the light pole above the stoplights. These can be visible light cameras or infrared cameras. The infrared cameras are not affected by vehicle headlights and are less affected by precipitation than a visible light camera, but they both work on the same principle of doing lots of image analysis to determine presence and speed of vehicles.

E-ZPass/Toll Booths

One of my hobbies while driving is to make funny faces at the toll booth cameras as I drive through them. I like to think that somewhere there is a database with photos attached to every time I’ve driven through a toll. The reality is that it’s probably purged after a few days and I’m making funny faces for no reason, but it does get the other occupants of my vehicle engaged.

The tags are active RFID transponders at 915Mhz, and draw very little current from their battery. We’ve covered E-ZPass a little in the past. The cameras are there to capture the license plate and verify the pass with the plate, or charge people driving through the toll without the electronic tag. The passes are useful outside of toll booths as well, so that scanners in other places can be used to populate travel time signs.

Road Tubes

These are rubber tubes that extend across the road to a base station. A vehicle passing over it compresses the tube briefly, and the change in pressure is measured at the station. The number of axles is detected, and with some tricky algorithms, the number of vehicles calculated. This can be difficult with cars driving over it simultaneously, vehicles with more than 2 axles, or other complicating situations, so error rates can be as high as 10%. When you see two tubes next to each other at a fixed distance apart, then it’s capable of calculating a lot more accurately, and it can give speed and direction.

As far as I can tell, road tubes are only data loggers and don’t upload information in real time yet, so you don’t need to worry about the road tubes being used as live speed traps.

Preemption

When an emergency vehicle is approaching, sometimes intersections will have sensors to detect this and change the traffic so that the light will allow them to pass. These sensors can be acoustic and listen for specific siren triggers, light-sensitive and watch for specific strobing patterns (flashing your headlights will not work), and radio. [Dan Maloney] recently discussed preemption hacking in more detail (hint: don’t).

Big Data

Many people now drive everywhere with Google Maps or Waze directing them. Their real time location is uploaded and used to determine if there are traffic jams, estimate drive time, and find alternate routes. It’s normal now for my phone to say “There is a slowdown causing a 10 minute delay. You are no longer on the fastest route.” Then I click a button and it redirects me to avoid the delay.

This kind of power is incredible and slightly disturbing. It can be used to save millions of hours of drive time and gallons of gas, but could also be exploited to redirect people or cause traffic jams.

Further Reading

If you want to go deep into the rabbit hole, the Federal Highway Administration has a surprisingly fascinating handbook on traffic detection. It’s slightly out of date at 2006, but covers most of these topics in great detail. If you know the story behind sensor technologies that I didn’t cover, we’d love to hear about the in the comments below.


Filed under: Featured, History, Original Art

Super Simple Hydraulics Using Syringes

พุธ, 08/09/2017 - 18:00

When making a toy excavator arm, or any robotic arm, the typical approach is to put motors at the joints, or if there isn’t room, to put the motors somewhere else and transfer the force using fishing line and pulleys. [Navin Khambhala] chose instead to do it more like the real excavators, with hydraulics using syringes. And we have to admit, the result it pretty elegant in its simplicity.

The syringes do the job of single-acting hydraulic actuators, one at the motor and the other where the force is needed. In between them, what appears to be clear vinyl tubes carry the fluid between syringes. 12 volt DC motors with bolts on them move nuts attached to the syringe pistons to push and pull the pistons. It is so simple that no further explanation is needed, though like most apparently simple things, we’re sure a lot of effort went into making it that way. The video below shows the finished product, as well as walks through the making of it.

And as for other methods of transferring force, for the ‘fishing line’ one, see or own [Joshua Vasquez]’s detailed articles on making working tentacles. For putting the motors at the joints the Pixar style lamp is always a fun one.


Filed under: robots hacks

Laser Cut Enclosures from Eagle Files

พุธ, 08/09/2017 - 15:00

Once a project is finished, it might still need a decent enclosure. While it’s possible to throw a freshly soldered PCB in a standard enclosure, or piece of Tupperware, or cardboard box, these options don’t have the fit and finish of something custom-made. If you have a laser cutter sitting around, it’s a simple matter to cut your own enclosure, but now that process is much easier thanks to [Ray]’s latest project.

Since [Ray] was already using Eagle to design his PCBs, it seemed like a short step to using the Eagle files to design the enclosure as well. The script runs from those files and creates everything necessary to send to the laser cutter for manufacturing. Right now, [Ray] points out that the assembly time for each enclosure can be high, and this method might not be suited for large numbers of enclosures. Additionally, some of the calculations still need to be done by hand, but there are plans to automate everything in the future.

For single projects, though, this script could cut a lot of time off of designing an enclosure and building it from scratch, and could also help improve aesthetics over other options like 3D printed enclosures. Of course, if you have a quality 3D printer around but no laser cutter, there are options for custom enclosures as well.


Filed under: laser hacks

ColibriNANO USB SDR Receiver Reviewed

พุธ, 08/09/2017 - 12:00

At first glance, the ColibriNANO SDR looks like another cheap SDR dongle. But after watching [Mile Kokotov’s] review (see video below), you can see that it was built specifically for software defined radio service. When [Mile] takes the case off, you notice the heavy metal body which you don’t see on the typical cheap dongle. Of course, a low-end RTL-SDR is around $20. The ColibriNANO costs about $300–so you’d hope you get what you pay for.

The frequency range is nominally 10 kHz to 55 MHz, although if you use external filters and preamps you can get to 500 MHz. In addition to a 14-bit 122.88 megasample per second A/D converter, the device sports an Altera MAX10 FPGA.

In addition to interfaces to different software packages, the dongle works with remote software. The idea is to put the dongle and an antenna somewhere advantageous (that is, high and radio-quiet) and then use a Raspberry Pi or similar computer to pipe signal over the Internet.

If you don’t want a dongle, we can endorse [Lukas’] build from scratch. If you are looking more for a getting started resource, check out what [Richard Baguley] had to say about SDR.

 


Filed under: radio hacks

DIY VT220 Keyboard

พุธ, 08/09/2017 - 09:00

There’s always been interest in the computers of old, and people love collecting and restoring them. When [peterbjornx] got his hands on a DEC VT220 video terminal, it was in good shape – it needed a bit of cleaning, but it also needed a keyboard. [Peter] couldn’t afford to buy the keyboard, but the service manual for it was available, so he decided to convert a modern keyboard to work with his new terminal.

The original keyboard for the VT220 is the LK201. This keyboard communicates with the terminal using 8-N-1 (eight data bits, no parity, one stop bit) over RS232 at 4800 baud. This meant that it would be pretty simple to implement this on microcontroller in order to communicate with the terminal. [Peter] chose the Arduino Nano. However, the LK200 was more than just a keyboard for communicating with the terminal, it also housed a speaker and LEDs which the terminal used to communicate with the user. Rather than put these into the adapter unit, [Peter] decided to put these into the keyboard – a few holes and a bit of wiring, and they were in.

[Peter]’s write-up includes a description of some of the issues he encountered as well as a picture of the keyboard. He’s put the schematic online and the code up on GitHub. In case you were wondering, he used Vim on the VT220 to write his article. You could also use a Raspberry Pi to help out your dumb terminal, or just hook the terminal directly to your Linux box and go from there.


Filed under: classic hacks, computer hacks, peripherals hacks

Starter Guide to Linux Forensics

พุธ, 08/09/2017 - 06:00

The old saying is if your data isn’t backed up at least twice, it’s not backed up at all. For those not wise enough to heed this adage, there are a number of options available to you if you wish your data to be recovered. Assuming the drive itself is just corrupted somehow (maybe a malicious attack, maybe a user error) and not damaged beyond physical repair, the first step is to connect the drive to another computer. If that fails, it might be time to break out the computer forensics skills.

[Luis]’s guide is focused on Linux-specific drives and recovery tools, so this isn’t necessarily a general-purpose how-to. That being said, there is a lot of information in this guide such as how to mount the target drive’s partitions, how to set up various timelines, and which of the Linux system’s logs are important for the forensic analysis. This specific example in the guide also goes into detail about noticing which of the recent files had been accessed, what they might have done, and different approaches to piecing the mystery of this corrupted drive together.

[Luis] points out that the world of Linux forensics is much different from that of Windows, but for anyone looking to get started he suggests starting with a clean Linux install and going from there. There are many other avenues of digital forensics, as well; the field has as many avenues of exploration as there are different types of computers.


Filed under: computer hacks

ATMega328 3D!

พุธ, 08/09/2017 - 03:00

Small OLED displays are inexpensive these days–cheap enough that pairing them with an 8-bit micro is economically feasible. But what can you do with a tiny display and not-entirely-powerful processor? If you are [ttsiodras] you can do a real time 3D rendering. You can see the results in the video below. Not bad for an 8-bit, 8 MHz processor.

The code is a “points-only” renderer. The design drives the OLED over the SPI pins and also outputs frame per second information via the serial port.

As you might expect, 3D output takes a good bit of math, and the chip in question isn’t very good at handling real numbers. [Ttsiodras] handles this using an old technique: fixed point arithmetic. The idea is simple. Normally, we think of a 16-bit word as holding unsigned values of 0 – 65535. However, if you choose, you can also use it to represent numbers from 0-50.999, for example. Mentally, you scale everything by 1,000 and then reverse the operation when you want to output. Addition and subtraction are straightforward, but multiplication and division require some extra work.

If you want to read more about fixed point math, you are in the right place. We’ve also covered a great external tutorial, too. But if you think this is the first time we’ve covered a 3D graphics engine for the ATmega parts, you’re wrong.


Filed under: Arduino Hacks

Hackaday Prize Entry: A BSTRD Preamp

พุธ, 08/09/2017 - 01:30

For this year’s Hackaday Prize, [skrodahl] is building a beautiful tube preamp. It’s a masterpiece of glass and free electrons, it already works, and it sounds great.

This circuit is a modified version of the Bastard, an amp published in the Danish magazine Ny Elektronik nearly 20 years ago. The original amp was a true bastard, with a transistor phono stage, a valve line stage, and an input selector that used relays. [skrodahl]’s version only uses the line stage, but part of the name remains as a nod to the original design.

The design of this amp uses octal 6J5 tubes, a 80 VDC, 0.1 A and 6 VDC, 1.5 A power supply. This is actually two projects in one, with the power supply comprising an another entire project.

[skrodahl]’s BSTRD is built, and it works, but the question remains: how does it sound? Unlike so, so many tube amp projects on the Interwebs, [skrodahl] actually has test and measurement gear to figure out what the frequency response and THD measurements actually are. For the frequency response, this amp is dead flat from 10 Hz to 30 kHz. THD is somewhere between 0.35-0.4%, or more than acceptable.

This is a great little project, and an awesome extension to an already popular Open Source project. It’s also a great entry for the Hackaday Prize, and we’re pleased to see it entered in this year’s contest.

The HackadayPrize2017 is Sponsored by:
Filed under: The Hackaday Prize

Eclipse Megamovie: Thousands of Cameras for Citizen Science

พุธ, 08/09/2017 - 00:01

On August 21, 2017, the Moon will cast its shadow across the entire breadth of the United States for the first time in almost a century. It is estimated that 12 million people live within the path in which the sun will be blotted out, and many millions more are expected to pour into the area to experience the wonders of totality.

We’d really love it if you would tell us where you’ll be during the eclipse by creating your own event page, but that’s not what this article’s about. With millions gathered in a narrow swath from Oregon to South Carolina, and with the eclipse falling on a Monday so that the prior two weekend days will be filled with campouts at prime viewing locations, I expect that Eclipse 2017 will be one big coast-to-coast party. This is an event that will attract people of all stripes, from those with no interest in astronomy that have only the faintest idea of what’s actually happening celestially, to those so steeped in the science that they’ll be calling out the exact beginning of totality and when to expect Baily’s Beads to appear.

I suspect our readership leans closer to the latter than the former, and some may want to add to the eclipse experience by participating in a little citizen science. Here’s how you can get involved.

The Eclipse Megamovie

A total solar eclipse is perhaps nature’s most photogenic event. With the glare of the Sun’s face blotted out by the Moon and the sky suddenly gone black, the sun’s atmosphere is clearly visible, forming a ghostly and beautiful halo around our star. Eclipse 2017 will be the first eclipse to be visible from the US in the era of digital photography, and millions of smartphones and DSLRs will be producing petabytes of coronal images during the two minutes of totality that any one stationary observer will experience.

But what if there were a way to extend totality to the full ninety minutes it’ll take for the Moon’s shadow to march across the country? Turns out there is a way to do just that, and you can be a part of it. The Eclipse Megamovie is a joint project between Google, UC Berkeley, and a host of other educational institutions that seeks to glue together images of the Sun’s corona taken by volunteers across the country. If all goes well — and cell phone networks don’t crash under the load — Google’s custom algorithms will begin stitching together images using EXIF data to correct for time and location into a 90-minute long study of the corona. All that’s needed to participate is a decent DSLR, at least a 300-mm telephoto lens, and a sturdy tripod.

Lack the camera gear but still want to participate? There’s an app for that. The Eclipse Megamovie Mobile app not only helps you plan where and when to see the eclipse, it also automates the Android device’s camera during totality. The images taken will be uploaded to the Megamovie project and help assemble the most massive dataset of Eclipse images ever assembled.

The opportunities for citizen science won’t stop after the Megamovie is created, though. As powerful as Google’s systems have become, the Megamovie effort will still be relying on the pattern recognition abilities of the Mark 1 human eyeball and visual cortex to find interesting features in the corona. To support these ongoing studies, the database of Megamovie images will be publically available and searchable.

Both the science and the beauty of Eclipse 2017 will be captured as never before possible, and the event will live long past a few minutes of totality thanks to efforts like the Megamovie. If you’ve got the means you should really consider pitching in. After all, your image could be the one that leads to a breakthrough.

Feature images: Rick Fienberg/TQI/WT, CC BY-NC-ND 4.0


Filed under: Current Events, news

Touchscreen Oscilloscope

อังคาร, 08/08/2017 - 22:30

[Marco Reps] didn’t want to lug a full-sized oscilloscope around to measure his ECG while running. He decided to check out the DSO112A which is a tiny touchscreen scope from the usual China sources. The tiny one channel scope can go to 2mV/division at 2MHz and can save and recall up to 24 configurations. It also has access to the data via a serial port so you can use it as a fancy data logger. [Marco’s] video appears below.

Apparently, there is was an older model without the A on the end that was not as sensitive and had some other missing features. The price is about $70–fairly inexpensive, although not throw-away cheap.

[Marco] noted that one of the two small connectors can act as an external trigger input or a function generator. There’s the typical LiPo battery inside and a shielded input section. [Marco] tears the board down and looks at the chips on the board. Inside are two Atmel CPUs and a 20 megasample per second analog to digital converter.

The color screen looks surprisingly good in the video although, as [Marco] points out, with one channel, the colors aren’t super useful. The device also has cursors and a nice selection of measurements that work both live and on stored data.

At the end of the video, [Marco] shows a simple ECG amplifier he built from an open source schematic. We’ve covered simple ECG circuits before if you want to read more.

Last year we looked at two small inexpensive scopes. Like everything else, each year the bar gets higher. Although, in fairness, those scopes had a (reported) 25 MHz bandwidth. We’d love to see that kind of front end with the user interface of the DSO112A.

 


Filed under: tool hacks

Know Thy LED

อังคาร, 08/08/2017 - 21:01

The invention of the LED is one of the most important discoveries of our times. They are everywhere, from our flashlights to household lighting and television sets. We don’t need to tell you that a project with more blinkies is better than a project with fewer blinkies. But an LED is not simply an LED; the sheer variety of LEDs is amazing, and so in this write-up, we’ll take a closer look at how to choose the right LED for your next masterpiece.

The LED Family Tree

The first official LED was created in 1927 by Russian inventor Oleg Losev, however, the discovery of electroluminescence was made two decades prior. British experimenter H. J. Round of Marconi Labs was the first to report the phenomenon in 1907. He found that silicon carbide would glow with a yellowish light when a potential of ten volts was applied to it. This set off years of experimenting with materials such as silicon carbide, gallium arsenide, gallium antimonide, indium phosphide, and silicon-germanium in an attempt to create a practical device.

In 1955, Rubin Braunstein reported infrared emission from gallium arsenide, however James R. Biard and Gary Pittman of Texas Instruments presented the first IR lamp (PDF) in 1961 which was the first practical LED to be patented in the August of the same year. Consequently, the first commercial LED was an IR LED with 890 nm light output and was called the SNX-100.

The era of the visible LED began in 1962 by Nick Holonyak, Jr. who was working at General Electric at the time. He discovered the red LED and published the results in the Applied Physics Letters on December 1, 1962 and currently holds around 41 patents to his name. He is known as the father of the visible LED and is also responsible for the laser diode commonly used in CD and DVD players. A decade later came the discovery of the yellow LED, M. George Craford, who happens to be a former graduate student of Holonyak.

 

The LED that Won the Nobel Prize

In 2014, three scientists, Isamu Akasaki, Hiroshi Amano, and Shuji Nakamura won the Nobel prize for inventing the blue LED in the early 1990s. Although RGB LEDs are obviously not possible without the “B”, the invention of the blue LED was important beyond the color. Blue LEDs are bright and efficient, and were the last stepping stone towards producing the white LED that illuminates the world today.

There are two methods to create white light from LEDs. The obvious method involves mixing three primary colors in the correct proportions to produce white illumination. The second method which is used to make white LEDs is the phosphor method where the blue LED shines onto a yellow phosphor coating.

In this method, the blue LED is used in conjunction with a yellow phosphor coating. The idea is to have part of the blue light converted into yellow light and leave a part of it in its original wavelength. When both these lights combine, they form a white beam which is far more efficient and pure than that from the first method.

Believe it or not, this discovery of color combination was made by Sir Isaac Newton in the early 1700s.

Behind their Glowing Personality

Regardless of the color, LEDs are all electroluminescent. Electroluminescence is the phenomenon wherein a material emanates light when an electrical current is passed through it. The underlying process involves the recombination of electrons and holes in the material. Check out this video for a quick summary and visualization.


An LED is a diode, or a PN junction. The types of materials used in the junction determines the color and intensity of light emitted. Voltage applied across the junction provides the energy to break electrons free from their parent atoms. The free valence electrons later recombine and release that energy as a photon. A typical LED construction is shown below. The semiconductor die is where the recombination happens and the photons are emitted. In order to channel this light, a reflective conical cavity is made and the epoxy lens on top allows for further collimation or diffusion of the light.

If the physics of the LED interests you then I suggest starting with The First Practical LED (PDF) as a reading resource.

 

Different materials used in the die preparation are as follows.

  • Aluminum gallium arsenide (AlGaAs) and gallium arsenide LEDs emit red and infrared
  • Gallium nitride LEDs emits bright blue
  • Indium gallium nitride (InGaN) emits blue, green and ultraviolet high-brightness light
  • Aluminum gallium nitride (AlGaN) LEDs emits ultraviolet
  • Yttrium aluminum garnet LEDs emits white
  • Gallium phosphide (GaP) LEDs emits reddish, yellow and green
  • Aluminum gallium indium phosphide (AlGaInP) yields yellow, orange and red high-brightness LEDs
  • Aluminum gallium phosphide(AlGaP) LEDs emits green

[Image: http://www.ledsupply.com/blog/what-you-need-to-know-about-leds/%5D

An LED for Every Reason

Beyond different colors, different LED materials lend themselves to different applications. Lower-intensity LEDs are typically employed as equipment indicators like in the case of router blinking lights. There could be as many as 100 LEDs on typical rack mount equipment and these should draw as little power as possible, but don’t need to be blindingly bright. Seven segment displays can have a luminous intensity (LI) as low as 260 ucd at 15 mA.

There are brighter LEDs that are designed for fog lamps and traffic lights and have LI of 34 cd at 350 mA (2.15V). It does not stop there either. LED grow lights are specifically targeted towards horticulture and indoor farming. There, a mix of blue and red light is usually used for growing plants in artificial lighting, although some companies claim that targeted lighting with 730 nm, 660 nm, and 450 nm provides the best balance of growth and efficiency.

And just when you thought things could not get any more complicated, we have the case of white LEDs. The color of light produced is measured on the Kelvin scale, where a lower number equates to a warmer light—the higher the number, the whiter, (and, yes, eventually bluer) the light will be.

Say What Watt?

LEDs intended for lighting, especially those sold on eBay, are often specified by how many watts they consume. For instance, this LED ad says 12 V and 20 W which by Ohm’s Law means a current consumption of 1.66 A. The wattage is the amount of power which the lamp ‘should’ consume at a particular supplied voltage, but isn’t a good measure of light output — for that you should be concerned with LI.

But wattage does matter. Assuming that an LED’s efficiency is roughly 50%, running that LED at 20 W means that around 10 watts will be dissipated as heat. Because the efficiency of an LED gets worse as it heats up, this kind of LED absolutely requires a heat sink if run at high currents. We’ll discuss this topic more in a future article on driving LEDs.

The Future Of LED Research

There is a lot of ongoing research in the field of LED manufacturing as well as basic material science that underlies it. In the case of manufacturing, work is focused on creating LEDs that are smaller so that they can be used in higher resolution displays. Patents such as this one for micro-reflectors on a substrate for high-density LED array are being filed every day. With wearables becoming more popular, a recent patent on flexible LED substrate devices is proof that we are on the path to flexible electronics.

There is also scope for higher efficiency LED designs as well as LED with better thermal management. UV LED design is still evolving and there is room to improve. published results suggest UV LED of up to 75 Watts are on the horizon.

The future is really bright and hopefully a lot more efficient.


Filed under: Featured, Interest, Original Art

Keep Pedaling to Keep Playing

อังคาร, 08/08/2017 - 18:00

It’s been said that the best way to tackle the issue of childhood obesity would be to hook those children’s video game consoles up to a pedal-powered generator. Of course, this was said by [Alex], the creator of Cykill. Cykill interfaces an Xbox to an exercise bike, so to keep the video game going you’ll have to keep pedaling the bike.

While there is no generator involved in this project, it does mimic the effect of powering electronics from a one. The exercise bike has a set of communications wires, which are connected to a relay on the Xbox’s power plug. When the relay notices that the bike isn’t being pedaled enough, it automatically cuts power to the console. Of course, the risk of corrupting a hard drive is high with this method, but that only serves to increase the motivation to continue pedaling.

The project goes even further in order to eliminate temptation to bypass the bike. [Alex] super-glued the plug of the Xbox to the relay, making it extremely difficult to get around the exercise requirement. If you’re after usable energy instead of a daily workout, though, there are bikes out there that can power just about any piece of machinery you can imagine.


Filed under: xbox hacks

A Hypnotizing Interactive Art Piece for Visualizing Color Theory

อังคาร, 08/08/2017 - 15:01

Digital color theory can be a tricky concept to wrap one’s mind around – particularly if you don’t have experience with digital art. The RGB color model is about as straightforward as digital color mixing gets: you simply set the intensity of red, green, and blue individually. The result is the mixing of the three colors, based on their individual intensity and the combined wavelength of all three. However, this still isn’t nearly as intuitive as mixing paint together like you did in elementary school.

To make RGB color theory more tangible, [Tore Knudsen and Justin Daneman] set out to build a system for mixing digital colors in a way that reflects physical paint mixing. Their creation uses three water-filled containers (one each for red, green, and blue) to adjust the color on the screen. The intensity of each color is increased by pouring more water into the corresponding container, and decreased by removing water with a syringe.

An Arduino is used to detect the water levels, and controls what the user sees on the screen. In one mode, the user can experiment with how the color levels affect the way a picture looks. The game mode is even more interesting, with the goal being to mix colors to match a randomly chosen color that is displayed on the screen.

The practical applications for this project may be somewhat limited, but as an interactive art piece it’s hypnotizing. And, it may just help you with understanding RGB colors for your next project.


Filed under: misc hacks

One Transistor RTL-SDR Upconverter

อังคาร, 08/08/2017 - 12:00

Even if you haven’t used one, you’ve probably seen the numerous projects with the inexpensive RTL-SDR USB dongle. Originally designed for TV use, the dongle is a software defined radio that many have repurposed for a variety of radio hacking projects. However, there’s one small issue. By default, the device only works down to about 50 MHz or so. There are some hacks to change that, but the cleanest way to get operation is to add an upconverter to shift the frequency you want higher. Sounds complicated? [Qrp-Gaijin] shows how to do it with a single transistor. You can see some videos of the results, below.

Actually, [Qrp-Gaijin] built an earlier version but wasn’t satisfied with the performance. He found that his original oscillator was driving an overtone crystal at its fundamental frequency. The device worked, but only because the oscillator was putting out harmonics, including the third harmonic at the actual needed frequency (49.8 MHz).

Changing the oscillator topology did the trick. A tuned circuit prevents the oscillator from having sufficient gain at the fundamental frequency. He did some other tweaks and–according to the post–he still has some future improvements he would like to make.

There have been efforts to improve the RTL-SDR circuitry, too. If you want to see a more complex upconverter, you might want to look at one based on circuit modules.


Filed under: radio hacks

Garage Distance Sensor Kicks Tennis Ball To Curb

อังคาร, 08/08/2017 - 09:00

Those with small garages might be familiar with the method of hanging a tennis ball from a ceiling to make sure they don’t hit the back wall with their car. If the car isn’t in the garage, though, the tennis ball dangling from a string tends to get in the way. To alleviate this problem, [asaucet] created a distance sensor that can tell him when his car is the perfect distance from the garage wall.

At the heart of the distance sensor is an HC-SR04 ultrasonic rangefinder and a PIC16F88 microcontroller. [asaucet] uses a set of four LEDs to alert the driver how close they are to the garage wall. [asaucet] also goes into great detail about how to use an LCD with this microcontroller for setting up the project, and the amount of detail should be enough to get anyone started on a similar project.

While this isn’t a new idea, the details that [asaucet] goes into in setting up the microcontroller, using the distance sensor, and using an LCD are definitely worth looking into. Even without this exact application in mind, you’re sure to find some helpful information on the project page.


Filed under: home hacks

Shoot the Eclipse with a Phone and Do Not Go Blind

อังคาร, 08/08/2017 - 06:00

So you want to photograph Eclipse 2017 but you don’t want to rush out and buy an expensive DSLR just for the event? Not a problem, if you build this simple smartphone filter and occluder.

It all started innocently enough for [Paul Bryson] with his iPhone and a lens from those cheap cardboard eclipse glasses we’re starting to see everywhere. Thinking that just taping the filter over the stock lens would do, [Paul] got a painful faceful of sunshine when he tried framing a shot. Turns out the phone body was not big enough to blot out the sun, and besides, the stock lens doesn’t exactly make for a great shot. So with an iPhone telephoto lens affixed to a scrap of wood and a properly positioned filter, [Paul] has a simple rig that’ll let him get some great pre-totality shots of the eclipse, and it’ll be easy to bust out the phone for two minutes of totality selfies. Looks like this setup would be easy to adapt to other phones, too.

We’re all over Eclipse 2017, from Hackaday Eclipse Meetups in at least four different points along the path of totality to experiments on relativity to citizen science efforts so you can get in on the action too. Mark your calendars – August 21 will be here before you know it.


Filed under: digital cameras hacks

Imaging Magnetism With A Hall Effect Camera

อังคาร, 08/08/2017 - 03:00

[Peter Jansen] is the creator of the Open Source Tricorder. He built a very small device meant to measure everything, much like the palm-sized science gadget in Star Trek. [Peter] has built an MRI machine that fits on a desktop, and a CT scanner made out of laser-

cut plywood. Needless to say, [Peter] is all about sensing and imaging.

[Peter] is currently working on a new version of his pocket sized science tricorder, and he figured visualizing magnetic fields would be cool. This led to what can only be described as a camera for magnetism instead of light. It’s a device that senses magnetic fields in two directions to produce an image. It’s cool, and oddly, electronically simple at the same time.

Visualizing magnetic fields sounds weird, but it’s actually something we’ve seen before. Last year, [Ted Yapo] built a magnetic imager from a single magnetometer placed on the head of a 3D printer. The idea of this device was to map magnetic field strength and direction by scanning over the build platform of the printer in three dimensions. Yes, it will create an image of field lines coming out of a magnet, but it’s a very slow process.

Instead of using just one magnetic sensor, [Peter] is building a two-dimensional array of magnetic sensors. Basically, it’s just a 12×12 grid of Hall effect sensors wired up to a bunch of analog multiplexers. It’s a complicated bit of routing, but building the device really isn’t hard; all the parts are easily hand-solderable.

While this isn’t technically a camera as [Peter] would need box or lens for that, it is a fantastic way to visualize magnetic fields. [Peter] can visualize magnets on his laptop screen, with red representing a North pole and green representing the South pole. Apparently, transformers and motors look really, really cool, and this is a perfect proof of concept for the next revision of [Peter]’s tricorder. You can check out a video of this ‘camera’ in action below.


Filed under: misc hacks

Hackaday Prize Entry: Powered Running Stroller Keeps You Running

อังคาร, 08/08/2017 - 01:00

Types of strollers called ‘running strollers’ exist to make it possible to bring your toddlers along for your run but try it with two four-year old, 38 lb young ones, against the wind, and up enough hills and you’ll quickly lose steam. [Andrew Clink]’s and his wife’s solution? Modify the stroller to be a self-powered roadrunner.

[Andrew]’s hackaday.io build logs are detailed, including design, calculations, schematics, 3D printing files, fails and retries, and more. Power is provided by a bank of lithium-ion batteries that drive a brushless motor. The motor turns the stroller’s front wheel using a toothed belt around a small motor pulley and a larger 3D printed wheel pulley, providing a 13.92:1 gear ratio. [Andrew] considered a number of methods for steering, and even tried a few, but given that his paths are mostly straight lines, small adjustments by hand are all that’s needed. For the possibility of the stroller getting away from him for whatever reason, [Andrew] wrote an iOS app for his phone that makes use of the Bluetooth LE Proximity profile (PDF). It communicates with a small remote using an nRF8001 Bluetooth connectivity IC and for added safety has a belt clip and a stop button.

Does it work? See for yourself in the video below. We’re sure [Andrew] and his wife will continue to be fit for a long time to come.

Maybe you’re not a runner and prefer to ride the stroller yourself? In that case you can do what  [Colin Furze] did and make a stroller that you can drive at over 53 miles per hour. Or perhaps it really is for your baby to ride themselves, with collision prevention features of course.

The HackadayPrize2017 is Sponsored by:
Filed under: The Hackaday Prize, transportation hacks

The Trouble With Cordless Power Tools

อังคาร, 08/08/2017 - 00:01

If you grow up around a small engineering business you are likely to gain something of an appreciation for power tools. You’ll see them of all ages, sizes, manufacturers, and technologies. When thinking of the power tools constantly on hand in the workshop of a blacksmith like my dad for instance, I’m instantly seeing a drill and an angle grinder. The drill that most comes to mind is a Makita mains powered hand drill, and given that I remember the day he bought it to replace his clapped-out Wolf in 1976, it has given phenomenal service over four decades and continues to do so.

41 years of hard use, and still going strong…

Of course, the Makita isn’t the only drill in his possession. A variety of others of different sizes and speeds have come and gone over the years, and there is always one at hand for any given task. The other one I’d like to single out is I think the most recent acquisition, a Bosch cordless model he bought several years ago. It’s similar in size and capabilities to the Makita save for its bulky battery pack, and it is a comparably decent quality tool.

So, we have two drills, both of similar size, and both of decent quality. One is from the mid 1970s, the other from the end of the last decade. One is a very useful tool able to drill holes all day, the other is little more than a paperweight. The vintage model from the days of flared trousers is a paperweight, you ask? No, the not-very-old Bosch, because its battery pack has lost its capacity. The inevitable degradation due to aged cell chemistry has left it unable to hold enough charge for more than maybe a minute’s use, and what was once a tool you’d be glad to own is now an ornament.

… Not so many years of light use, can’t say the same.

Naturally, this will not be unfamiliar to most Hackaday readers. We’ve all been offered a pile of dead cordless tools over the years, and as writers we’ve covered quite a few inventive hacks using them. They’re a useful source of motors and sometimes even speed controllers, even if you don’t want to use them as tools.

Comparing the Makita and the Bosch as exemplars of the two strands of power tool ownership, I have though to admit an unease over the rise of cordless tools, and a dislike of the marketing that surrounds them. In converting their customers to cordless tools, the manufacturers have found a way to get them to buy the same tool from them every five years or so when there is nothing wrong with their previous tool, simply because its battery pack has reached the end of its lifetime. Battery pack form factors change with each successive generation of tools, so the customer can not merely buy a new battery pack and move on. Great for the manufacturers, awful for the consumers.

Meanwhile of course, the marketing machine is in full swing pushing the convenience of cordless tools. Amazingly this often concentrates on those problematic batteries themselves, for example where this is being written the manufacturer of those lime-green power tools has a commercial promoting a range of tools that all have the same battery. The idea presumably being that after five years you won’t simply have to replace your drill due to a dead battery, you’ll have to replace all your tools!

“You might as well take that lot away with you Kevin, I’ll have to replace them all in a few years anyway!”. (Ryobi TV)

Of course, a full-on rant against power tool built-in obsolescence is of little use though without some kind of solution. If we’re to identify a problem then we should also provide some way out of it, at least a way that works for we hardware hackers and makers if not for the wider public.

The most obvious way to avoid cordless tool obsolescence is to not buy a cordless tool in the first place. Think carefully, how often do you use a power tool away from a mains socket? Really how often, not just hypothetically. The chances are it won’t be that often, if at all, and buying an extension cord with your electric drill will be a lot cheaper than buying a replacement drill in five years time. And then there are the unexpected benefits, you forget just how lightweight a power tool is when it doesn’t have a battery pack strapped to its handle. Buy a tool with a cord, and like my dad with his Makita, you might still be using it in four decades from now.

Repair

But let’s say you have a cordless tool, and its battery is failing. Can you fix the battery? Of course you can. You are Hackaday readers, you’ll all be aware that inside almost all cordless tool batteries you’ll find a set of standard off-the-shelf cells wired together, C or D cells in the case of NiCd or NiMh packs, and maybe 18650 cells for LiIon. If you can defeat the efforts of your tool manufacturer to discourage battery pack dismantling, you can have them out on your bench, and replace them.

This is a rather nicely built tab welder we recently featured.

Of course, there is a snag to replacing cells in a pack. This isn’t like the spring-loaded battery compartment in your radio, each cell will have spot-welded metal strip conductors linking it to its neighbour, and you’ll have to come up with a way of replicating that. If you’re lucky you’ll find solderable batteries, otherwise you’ll have to consider a battery welder. But if you can overcome that hurdle, you should at least be able to replace your cells without breaking the bank.

You will be unlikely to find a tool with a NiCd battery for sale new these days, but there are still huge numbers of older ones with dead packs to be found often at next-to-no outlay. It’s not the safest of exploits, but it is possible to rejuvenate dead NiCd cells with the application of short bursts of high current. The theory goes that metal crystals grow in the cell and short it out, and the high current blows these metal crystals and brings the cell back to life. There are tales of this being performed with hefty bench power supplies, car batteries, and arc welders, though you may wish to research carefully before you give it a try.

Finally, who needs cells? If you have a suitably powerful low voltage supply, why not run your tool directly from it and forget about the battery pack? Of course, you lose the ability to run it as a cordless tool, but if it came to you at very little cost than that should present very little hardship. Try a modified PC power supply if it’s a 12 V tool, or a lead-acid pack if it isn’t.

So we’ve got past my rant about the iniquity of the built-in obsolescence of cordless power tools, and identified several ways that we as resourceful Hackaday readers can benefit from the cast-offs of others whose batteries have reached the end of their lives. It doesn’t change my personal view that I’d always still buy a tool with a cord by choice, but at least there are ways forward for those stuck with failing cordless tools. Do you share my feelings on this topic?


Filed under: Featured, rants, tool hacks