Join [Sylvia Wu], a Senior Manufacturing Engineer at Fictiv, for this week’s Hack Chat. [Sylvia’s] work at Fictiv gives her a unique viewpoint for modern manufacturing. The company connects engineers with rapid manufacturing by taking in a design and routing it to a shop that has the tools and time to fabricate the part quickly. This means seeing the same silly mistakes over and over again, but also catching the coolest new tricks as they pass by. She also spends time tearing apart consumer products to see how they have been manufactured, adding to their arsenal of available processes, both time-tested and newfangled.
Anyone interested manufacturing needs to get in on this Hack Chat. Mark your calendar for this Friday, 3/10 at noon PST (20:00 UTC)Here’s How To Take Part:
Our Hack Chats are live community events on the Hackaday.io Hack Chat group messaging.
Log into Hackaday.io, visit that page, and look for the ‘Join this Project’ Button. Once you’re part of the project, the button will change to ‘Team Messaging’, which takes you directly to the Hack Chat.
You don’t have to wait until Friday; join whenever you want and you can see what the community is talking about.Upcoming Hack Chats
On Friday March 17th the Hack Chat features chip design for oscilloscopes with engineers from Keysight.
Filed under: cnc hacks, Hackaday Columns
To a radio amateur who received their licence decades ago there is a slightly surreal nature to today’s handheld radios. A handheld radio should cost a few hundred dollars, or such was the situation until the arrival of very cheap Chinese radios in the last few years.
The $20 Baofeng or similar dual-bander has become a staple of amateur radio. They’re so cheap, you just buy one because you can, you may rarely use it but for $20 it doesn’t matter. Most radio amateurs will have one lying around, and many newly licensed amateurs will make their first contacts on one. They’re not even the cheapest option either, if you don’t mind the absence of an LCD being limited to UHF only, then the going rate drops to about $10.
The Baofengs and their ilk are great radios for the price, but they’re not great radios. The transmitter side can radiate a few too many harmonics, and the receivers aren’t the narrowest bandwidth or the sharpest of hearing. Perhaps some competition in the market will cause an upping of the ante, and that looks to be coming from Xiaomi, the Chinese smartphone manufacturer. Their Mijia dual-band walkie-talkie product aims straight for the Baofeng’s jugular at only $35, and comes in a much sleeker and more contemporary package as you might expect from a company with a consumer mobile phone heritage. Many radio amateurs are not known for being dedicated followers of fashion, but for some operators the sleek casing of the Mijia will be a lot more convenient than the slightly more chunky Baofeng.
This class of radio offers more to the hardware hacker than just an off-the-shelf radio product, at only a few tens of dollars they become almost a throwaway development system for the radio hacker. We’ve seen interesting things done with the Baofengs, and we look forward to seeing inside the Xiaomi.
We brought you a look at the spurious emissions of this class of radio last year, and an interesting project with a Baofeng using GNU Radio in a slightly different sense to its usual SDR function.
[via Southgate ARC]
Filed under: radio hacks
It is so often the case with a particular technological advance, that it will be invented almost simultaneously by more than one engineer or scientist. People seem to like a convenient tale of a single inventor, so one such person is remembered while the work of all the others who trod the same path is more obscure. Sometimes the name we are familiar with simply managed to reach a patent office first, maybe they were the inventor whose side won their war, or even they could have been a better self-publicist.
When there are close competitors for the crown of inventor then you might just have heard of them, after all they will often feature in the story that grows up around the invention. But what about someone whose work happened decades before the unrelated engineer who replicated it and who the world knows as the inventor? They are simply forgotten, waiting in an archive for someone to perhaps discover them and set the record straight.
[Oleg Losev] (Public domain)Meet [Oleg Losev]. He created the first practical light-emitting diodes and the first semiconductor amplifiers in 1920s Russia, and published his results. Yet the world has never heard of him and knows the work of unrelated American scientists in the period after the Second World War as the inventors of those technologies. His misfortune was to born in the wrong time and place, and to be the victim of some of the early twentieth century’s more turbulent history.
[Oleg Losev] was born in 1903, the son of a retired Russian Imperial Army officer. After the Russian Revolution he was denied the chance of a university education, so worked as a technician first at the Nizhny Novgorod Radio laboratory, and later at the Central Radio Laboratory in Leningrad. There despite his relatively lowly position he was able to pursue his research interest in semiconductors, and to make his discoveries.Losev’s LED
When experimenting with a point-contact semiconductor junction on silicon carbide and zinc oxide crystals, he observed a greenish light emission from the junction. This had been observed before but not characterised, and he was able to prove that it was not a thermal effect before postulating that it might have its source in a quantum mechanism.
He continued to work on the effect, but because of the chosen semiconductor materials he was unable to significantly increase its light output. Without enough intensity to rival other lamps of the day it failed to attract enough interest despite his publishing multiple papers detailing his work and its applications. It was left to [Robert Baird] and [Gary Pittman] at Texas Instruments in the 1960s to pick up the baton with their infra-red LED, and for [Nick Holonyak] at General Electric to produce one with visible light shortly afterwards.Semiconductor Amplifiers And More An oscillator built to [Losev]’s zincite negative resistance diode design.
Hugo Gernsback [Public domain]
The detectors in many radio receivers of the day were simple “Cat’s Whisker” devices, point contact diodes where the junction was formed between a piece of wire and a naturally occurring crystal. It had been noticed that when a DC bias was used with these devices to overcome their forward voltage drop and make them more sensitive, it could occasionally cause the circuit to oscillate. [Losev] became interested in this phenomenon, and identified it as negative resistance, a semiconductor property whereby the curve has a region that behaves opposite to Ohm’s Law with current through it decreasing as voltage increases.
He was able to make reliable negative resistance diodes using zinc oxide crystals, and to configure them as oscillators and amplifiers in the same way as we might now with a more recent tunnel diode. As well as oscillators and amplifiers he created solid state radio receivers, both regenerative and superhetrodyne, several decades before [John Bardeen], [William Shockley], and [Walter Brattain] invented the first transistor at Bell Labs in 1948.
The Soviet authorities did not see the potential in this most exciting of inventions because [Losev]’s diodes could not replicate the performance of the tubes of the day, so given that the zinc oxide crystals were an expensive import from the USA the project was shelved. It was left to [Leo Esaki] at Sony in 1957 to rediscover negative resistance diodes with his discovery of electron tunneling, for which he later received a Nobel Prize.
[Losev]’s tale is a succession of moments of what might have been. He found himself trapped in Leningrad, now St. Petersburg, when it was besieged by the Germans in 1942, and like many others in the city he died of starvation. It is reported that before his death he was working on a three-terminal semiconductor amplifier device, which might have delivered the transistor to the Soviets years before it was invented by the Americans.
If [Losev]’s story has interested you, have a look at our profile of another largely unsung hero of early electronics: [Rufus Turner].
Filed under: Featured, History, Original Art, parts
If your favourite programming language is solder, they you’ve surely worked your way through a bunch of irons and controllers over your hacker existence. It’s also likely you couldn’t pick one single favourite and ended up with a bunch of them crowding your desk. It would be handy to have one controller to rule them all. That’s just what [sparkybg] set out to do by building his Really Universal Soldering Controller. His intent was to design a controller capable of driving any kind of low voltage soldering iron which used either an in-line or separate temperature sensor (either thermocouple or resistive PTC).
This project has really caught on. [sparkybg] announced his build about two years back and since then many others have started posting details of their own Unisolder 5.2 builds. [zed65] built the version seen to the right and [SZ64] assembled the boards shown at the top of this article.
The controller has been proven to work successfully with Iron handles from Hakko, Pace, JBC, Weller, Ersa, as well as several Chinese makes. Getting the controller to identify one of the supported 625 types of iron profiles consists of connecting two close tolerance resistors across the relevant pins on the 9-pin shell connector. This is a brilliant solution to help identify a large variety of different types of irons with simple hardware. In the unlikely situation where you have a really vague, unsupported model, then creating your own custom profile is quite straightforward. The design is highly discrete with an all analog front end and a PIC32 doing all the digital heavy lifting.
To get an idea of the complexity of his task, here is what [sparkybg] needs to do:
“I have around 200 microseconds to stop the power, wait for the TC voltage to come to its real value, connect the amplifier to this voltage, wait for the amplifier to set its output to what I want to read, take the measurement from the ADC, disconnect the amplifier from the TC, run the PID, and eventually turn the power back on. The millivolts to temperature calculation is done using polynomial with 10 members. It does this calculation using 32bit mantissa floating point numbers and completes it in around 20 microseconds. The whole wave shaping, temperature calculation, PID and so on is completed in around 50-60 microseconds. RMS current, voltage and power calculations are done in around 100 microseconds. All this is done between the half periods of the mains voltage, where the voltage is less than around 3 volts.”
The forum is already over 800 posts deep, but you can start by grabbing the all important schematic PDF’s, Gerbers, BoM and firmware files conveniently linked in the first post to build your own Unisolder5.2 controller. This Universal Controller is a follow up to his earlier project for a Hakko T12/T15 specific controller which gave him a lot of insight in to designing the universal version.
[sparkybg] has posted several videos showing the UniSolder5.2 controlling several types of Irons. In the video after the break, he demonstrates it controlling a Weller WSP80.
Filed under: hardware
The latest from WikiLeaks is the largest collection of documents ever released from the CIA. The release, called ‘Vault 7: CIA Hacking Tools Revealed’, is the CIA’s hacking arsenal.
While Vault 7 is only the first part in a series of leaks of documents from the CIA, this leak is itself massive. The documents, available on the WikiLeaks site and available as a torrent, detail the extent of the CIA’s hacking program.
Of note, the CIA has developed numerous 0-day exploits for iOS and Android devices. The ‘Weeping Angel’ exploit for Samsung smart TVs, “places the target TV in a ‘Fake-Off’ mode, so that the owner falsely believes the TV is off when it is on.” This Fake-Off mode enables a microphone in the TV, records communications in the room, and sends these recordings to a CIA server. Additionally, the CIA has also developed tools to take over vehicle control systems. The purpose of such tools is speculative but could be used to send a moving car off the road.
It is not an exaggeration to say this is the most significant leak from a government agency since Snowden, and possibly since the Pentagon Papers. This is the documentation for the CIA’s cyberwarfare program, and there are more leaks to come. It will be a while until interested parties — Hackaday included — can make sense of this leak, but until then WikiLeaks has published a directory of this release.
Header image source (CC BY 2.0)
Filed under: news, security hacks
Putting a complete WiFi subsystems on a single-board computer is no mean feat, and on as compact a board as the Zero W, it’s quite an achievement. The antenna is the tricky part, since there’s only so much you can do with copper traces.
The new Raspberry Pi Zero W’s antenna is pretty innovative, but sometimes you need an external antenna to reach out and touch someone. Luckily, adding an external antenna to the Zero W isn’t that tough at all, as [Brian Dorey] shows us. The Pi Zero W’s designers thoughtfully included solder pads for an ultra-miniature surface-mount UHF jack. The jack pads are placed very close to the long, curving trace that acts as a feedline to the onboard antenna. There’s even a zero ohm SMT resistor that could be repositioned slightly to feed RF to the UHF jack. A little work with a soldering iron and [Brian]’s Pi was connected to an external antenna.
[Brian] includes test data, but aside from a few outliers, the external antenna doesn’t seem to offer a huge advantage, at least under his test conditions. This speaks to the innovative design of the antenna, which [Roger Thornton] from the Raspberry Pi Foundation discussed during last week’s last week’s Hack Chat. Check out the archive for that and more.
Thanks to [theEngineer] for the tip.
Filed under: radio hacks, Raspberry Pi
The last year has been great for Nvidia hardware. Nvidia released a graphics card using the Pascal architecture, 1080s are heating up server rooms the world over, and now Nvidia is making yet another move at high-performance, low-power computing. Today, Nvidia announced the Jetson TX2, a credit-card sized module that brings deep learning to the embedded world.
The Jetson TX2 is the follow up to the Jetson TX1. We took a look at it when it was released at the end of 2015, and the feelings were positive with a few caveats. The TX1 is still a very fast, very capable, very low power ARM device that runs Linux. It’s low power, too. The case Nvidia was trying to make for the TX1 wasn’t well communicated, though. This is ultimately a device you attach several cameras to and run OpenCV. This is a machine learning module. Now it appears Nvidia has the sales pitch for their embedded platform down.Embedded Deep Learning
The marketing pitch for the Jetson TX2 is, “deep learning at the edge”. While this absolutely sounds like an alphabet soup of dorknobabble, it does parse rather well.
The new hotness every new CS grad wants to get into is deep learning. It’s easy to see why — deep learning is found in everything from drones to self-driving cars. These ‘cool’ applications of deep learning have a problem: they all need a lot of processing power, but these are applications that are on a power budget. Building a selfie drone that follows you around wouldn’t be a problem if you could plug it into the wall, but that’s not what selfie drones are for.
The TX2 is designed as a local deep learning and AI platform. The training for this AI will still happen in racks of servers loaded up with GPUs. However, the inference process for this AI must happen close to the camera. This is where the Jetson comes in. By using the new Nvidia Jetpack SDK, the Jetson TX2 will be able to run TensorRT, cuDNN, VisionWorks, OpenCV, Vulkan, OpenGL, and other machine vision, machine learning, and GPU-accelerated applications.Specs Jetson TX2 Module (and its heatsink) installed on the larger development board.
Like the Nvidia TX1 before it, the Jetson TX2 is a credit card-sized module bolted onto a big heatsink. The specs are a significant upgrade from the TX1:
- Graphics: Nvidia Pascal GPU, 256 CUDA cores
- CPU: Dual-core Denver + quad-core ARM A57
- RAM: 8GB 128-bit LPDDR4
- Storage: 32GB EMMC, SDIO, SATA
- Video: 4k x 2x 60Hz Encode and Decode
- Display: HDMI 2.0, eDP 1.4, 2x DSI, 2x DP 1.2
- Ports and IO: USB 3.0, USB 2.0 (host mode), HDMI, M.2 Key E, PCI-E x4, Gigabit Ethernet, SATA data and power, GPIOs, I2C, I2S, SPI, CAN
The Jetson development kit is the TX2 module and a breakout board that is effectively a MiniITX motherboard. This is great for a development platform, but not for production. In the year and a half since the release of the Jetson TX1, at least one company has released carrier boards that break out the most commonly used peripherals and ports. The hardware interface of the TX2 is backward compatible with the TX1, so these breakout boards may be used with the newer TX2.
The TX2 module will be available in 2Q17, with pricing at $399 in 1k quantities. The development kit will cost a bit more. If you’d like to develop your own breakout for the TX2, the physical connector is sourceable, and the manufacturer is extremely liberal with sample requests.
Filed under: Featured, hardware, news
One of the most challenging projects you could ever do with an 8-bit microcontroller is generating VGA signals. Sending pixels to a screen requires a lot of bandwidth, and despite thousands of hackers working for decades, generating VGA on an 8-bit microcontroller is rarely as good as a low-end video card from twenty years ago.
Instead of futzing around with microcontrollers, [Marcel] had a better idea: why not skip the microcontroller entirely? He’s generating VGA frames from standard logic chips and big ‘ol EEPROMs. It works, and it looks good, too.
VGA signals are just lines and frames, with RGB pixel values stuffed in between horizontal sync pulses, and frames stuffed between vertical sync pulses. If you already know what you want to display, all you have to do is pump the right bits out through a VGA connector fast enough. [Marcel] is doing this by saving images on two parallel EEPROMs, sending the output through a buffer, through a simple resistor DAC, and out through a VGA connector. The timing is handled by a few 74-series four-bit counters, and the clock is a standard 25.175 MHz crystal.
There’s not much to this build, and the entire circuit was assembled on a breadboard. Still, with the clever application of Python to generate the contents of the ROM, [Marcel] was able to build something that displays eight separate images without using a microcontroller.
Filed under: hardware
A few months ago, someone clued us in on a neat little programmable power supply from the usual Chinese retailers. The DPS5005 is a programmable power supply that takes power from a big AC to DC wall wart and turns it into a tiny bench-top power supply. You can pick one of these things up for about thirty bucks, so if you already have a sufficiently large AC to DC converter you can build a nice 250 Watt power supply on the cheap.
[Johan] picked up one of these tiny programmable power supplies. His overall impression was positive, but like so many cheap products on AliExpress, there wasn’t a whole lot of polish to the interface. Additionally, the DPS5005 lacked the ability to be controlled over a serial port or WiFi.
This programmable power supply is built around an STM32, with the programming pads exposed and labeled on the PCB. The changes [Johan] wanted to make were all in software, leading him to develop OpenDPS, a firmware replacement for the DPS5005.
To write his own firmware for this power supply, [Johan] first had to get his computer talking to the main chip controlling the power supply. That was quick work with an STLink programmer, however the readout protection for the microcontroller was set. That put an end to reverse engineering the firmware, but that really didn’t matter – he was only interested in what the microcontroller talked to. After some work, [Johan] managed to figure out how to interact with the buttons, current limiter, ADC goodies, and the TFT display. An application was written with a vastly improved UI, with support for an ESP8266 plugged into the UART pins.
Right now, [Johan] has a significantly better power supply that can be programmed over WiFi. All the code is available, and there’s even a guide for hacking one of these power supplies. This is fantastic work, and we could only be so lucky if a random Chinese factory takes note and puts this firmware into their production line.
Filed under: hardware, tool hacks
Cyber security is on everyone’s minds these days. Embedded devices like cameras have been used by bad guys to launch attacks on the Internet. People worry about data leaking from voice command devices or home automation systems. And this goes for the roll-your-own systems we build and deploy.
Many network-aware systems use Linux somewhere — one big example is pretty much every Raspberry Pi based project. How much do you think about security when you deploy a Pi? There is a superior security system available for Linux (including most versions you’d use on the Pi) called SELinux. The added letters on the front are for “Security-Enhanced” and this project was originally started by the NSA and RedHat. RedHat actually has — no kidding — a coloring book that helps explain some of the basic concepts.
We aren’t so sure the coloring book format is really the right approach here, but it is a light and informative read (we didn’t stay in the lines very well, though). Our one complaint is that it doesn’t really show you anything in practice, it just explains the ideas behind the different kind of protections available in SELinux. If you want to actually set it up on Pi, there’s a page on the Pi site that will help. If you have an hour, you can get a good overview of using SELinux in the video below.
By default, the Linux security model is pretty simple. You have four conceptual groups of people: the root user, the owner of something, groups of users, and everyone who doesn’t fit in any of the previous categories. Files and things that look like files can have read, write, and execute permissions that apply to the owner, the owner’s group, and everyone. There are some special rules for directories and a few other features, but that’s it in a nutshell. It is easy to make a file (like a shell script) that you can read, write and execute. Maybe users in your group can read and execute, and everyone else can only execute. On some Pi systems, this is probably fine because you are the only user anyway, so groups and all don’t make much sense. However (as you’ll see in the video) using it to control access from, say, a web server, can make your system less vulnerable to attack.
With SELinux you can put labels on processes and file system objects and use those to control access. The example in the coloring book focuses on making sure dogs eat the right dog food and cats eat cat food. You can get very fine-grained control using these methods. You can also use MLS (multi-level security) like the government does and have things be secret, top secret, etc.
Take some time to make sure you get basic Linux security right. This way hackers (the bad kind, not our kind) will have to work a lot harder to cause mayhem. We’ve seen some pretty incredible efforts like hacking a modern Linux box with 6502 code aimed at the Nintendo. It is no secret that Internet-connected devices are becoming a target of choice for the black hats.
Filed under: linux hacks, Raspberry Pi
In my misspent youth I found myself doing clinical rotations at a local hospital. My fellow students and I were the lowest of the low on the hospital pecking order, being the ones doing the bulk of the work in the department and paying for the privilege to do so. As such, our locker facilities were somewhat subpar: a corner of a closet behind a door labeled “COMMS”.
In the room was a broken chair and a couple of hooks on the wall for our coats, along with an intriguing (to me) electrical panel. It had a series of rectangular blocks with pins projecting from it. Each block had a thick cable with many pairs of thin, colorful wires fanned out and neatly connected to the left side, and a rats nest of blue and white wires along the right side. We were told not to touch the board. I touched it nonetheless.
I would later learn that these were Type 66 punchdown blocks for the department’s phone system, and I’d end up using quite a few of them over my hacking life. Punchdown connectors were a staple of both private and public telco physical plants for decades, and belong to a class of electrical connections called insulation displacement connections, or IDC. We’ve recently looked at how crimp connections work, and what exactly is going on inside a solder joint. I thought it might be nice to round things out with a little bit about the workings of IDC.The Need for (More) Speed
As crimp connections were an attempt by the electrical and electronic industry to increase the efficiency of assembly by eliminating the labor-intensive step of soldering connections, so too was insulation displacement developed to save time relative to crimping. As efficient as crimp connections are compared to hand-soldered joints, crimping still takes a fair amount of manual labor in most cases. And even where an assembly process is complicated enough to warrant automatic crimping, there are still multiple steps involved in completing the crimp — stripping insulation, inserting the wire into the crimp connector, and applying crimp pressure, perhaps multiple times. IDCs eliminate the wire preparation steps and result in faster connections with fewer tooling changes, and are much more amenable to mass-termination of conductors.
The first US patent for IDC was issued in 1961 to two inventors working for the Minnesota Mining and Manufacturing Corp. 3M is still big into IDC connectors even now; few of us who have installed a radio or remote starter in a car won’t be familiar with Scotchlock connectors for making taps into a car’s wiring. The original patent illustrations show a striking similarity to the Scotchlocks we still use today, and reveal the basic idea behind all IDCs. A slotted metal blade forms the heart of the IDC, with the slot sized to just under the diameter of the wire to be attached.In the Slot US Patent 3,012,219
When an insulated wire is placed in the slot and the appropriate amount of downward pressure is applied, the slot cuts into and moves aside the plastic insulation, exposing the conductor within. As the termination pressure increases, the wire contacts the sides of the slot and begins to deform; in much the way that wire strands inside a crimped connection begin to flow and stretch, so too does the wire in the slot effectively cold weld to the metal contact, forming a gas-tight connection. And like in the crimped connection, the deformation caused by the increased pressure acts to loosen and drive off surface oxidation that would interfere with a clean connection.
Of course this is a generalized case; details of each IDC are particular to the job they’ll be asked to do. Some contact slots are tapered, some are straight; sharpened blades in the slot may be called for in one application while blunt blades work better in others; some slots are spring loaded while others aren’t. And the methods used to terminate these connectors vary wildly as well. A simple Scotchlock up under the dash might need nothing more than a pair of pliers, while tooling for mass-terminating the ribbon cable of an ATA connector will be a more complex press that can spread the force evenly over a long set of contacts.
In the telco space, those 66 blocks in that would-be locker room of yore would have been terminated with a handheld punchdown tool with a type 66 bit. The punchdown tool itself is a spring loaded impact tool; when the hardened steel bit is placed over the contact with the wire loaded in the slot, downward pressure begins both pushing the wire into the contact slot and pushing the bit back into the tool body against spring pressure. When the proper pressure has been applied, the spring triggers a hammer to impact on an anvil, driving the bit down to complete the connection with just the right amount of pressure. Type 66 bits have a sharpened blade on one side of the bit that can trim excess wire as it’s being punched down, or a blunt bit can be used to daisy-chain connections.
IDCs are everywhere these days — automotive wiring harnesses, likely every appliance in your house, and dozens inside most computers. And even though IDC was once strictly reserved for low-voltage connections, chances are good that you’ll start seeing IDC used more and more for residential and commercial mains wiring. The advantages of being able to make a quick, solid, gas-tight electrical connection without multiple tools and manual operations are just too appealing to pass up.
Filed under: Engineering, Featured, tool hacks
Just because you have a fancy new 3D printer doesn’t mean that innovation should stop there. Almost everyone has had a print go foul if the first layer doesn’t properly adhere to the printing platform — to say nothing of difficulty in dislodging the piece once it’s finished. Facing mixed results with some established tricks meant to combat these issues, [D. Scott Williamson] — a regular at Chicago’s Workshop 88 makerspace — has documented his trials to find a better printer platform.
For what he had (a printer without a heated plate), painter’s tape and hairspray wasn’t cutting it, especially when it came time to remove the print as the tape wouldn’t completely come off the part. How then, to kill two birds with one stone? Eureka! A flexible metal covering for the printing plate.
The first test was with some aluminium flashing, once rolled out and cleaned, double-coated with hairspray and dried with a heat gun, and secured to the printing platform with clips. Unfortunately, that failed, along with a test using a wet coat of hairspray. However, the same plate with a coat from a glue stick worked almost perfectly!
Next up was a steel plate using the glue-and-clip-down method, which yielded similarly successful results. The catch with using the clips is that it subtly warps the steel, which could cause printing deformities. How to mitigate the problem? Magnets, obviously.
[Williamson] used a sheet of “refrigerator magnet material” secured to the printing platform with double sided tape, and the steel plate laid on top. A quick coating from a glue stick and test print later produced his most successful results. The method is reliable as long as the glue was cleaned off every few prints. The only caveat is that if the print does somehow get snagged by the print head, the relatively weak magnet doesn’t stand a chance, with the entire plate becoming dislodged!
A few years ago, we featured a home-built manufacturing line that used a similar concept, allowing a robot to replace printing platforms while the owner was out.
Filed under: 3d Printer hacks
If you’ve hung around electronics for any length of time, you’ve surely heard of the decibel (often abbreviated dB). The decibel is a measure of a power ratio. Actually, the real measure is a bel, but you almost never see that in practice. If you are versed in metric, you won’t be surprised to learn a decibel is 1/10 of a bel. Sometimes in electronics, we deal with really large ratios, so the decibel is logarithmic to cope with this. Doubling the number of decibels doesn’t double the ratio, as you will soon see. It’s all about logarithms, and this ends up being extremely useful when measuring something like antenna or amplifier gain.
Besides antennas, decibels are often used to measure sound and light. The reason is that human ears and eyes have a logarithmic response to those quantities. Your ear, for example, has a huge dynamic range. That is to say, you can hear a whisper or a space shuttle launch. That ratio is about 1 trillion to 1, but that’s only 120 dB. This is also why potentiometers made for volume controls have a logarithmic taper. A linear pot would seem off because, for example, a tenth of a turn at one extreme will affect the apparent volume much more than a tenth of a turn at the other extreme. This holds true whether or not those knobs go up to eleven.History
The decibel can trace its roots back to the old phone system. Originally, the unit used to measure loss in telephone and telegraph cables was “miles of standard cable” (MSC). There was an elaborate definition of what a standard cable was and 1 MSC was the amount of loss of a predefined signal over a mile of this cable. This went on until 1924.
That was the year Bell telephone introduced the Transmission Unit (TU) which was later (in 1928) called a bel, to honor Alexander Graham Bell (the chap on the left). We don’t know what happened to the last L in Bell’s name. It caught on, and we still use it today to measure gain and loss (loss shows up as a negative number).Why?
In addition to being handy for representing large ratios, the decibel also makes it easy to calculate system gain or loss. For example, if you have a transmitter that feeds coax with a -3 dB loss, an amplifier with a 25 dB gain, a cable run with -3.3 dB loss, and then an antenna with a 3 dB gain, you can simply add them all up: -3 + 25 – 3.3 + 3 = 21.7 dB. That’s a total gain of about 148 times ( log(148)=2.17 bels=21.7 dB — see the section below for help with these calculations).
Notice how losses show up as negative decibels? You may wonder, though, what does it mean to have an antenna with 3 dB gain? By the formula, that means the output of the antenna is 3 dB (right around twice) the input. However, it is difficult (and perhaps not too useful) to measure the power output since it isn’t really a two terminal device. Instead, antennas are measured by their gain over an isotropic antenna (an unbuildable antenna that is a single point in space that radiates the input power evenly in all directions). Of course, that’s not really practical, so sometimes you measure the gain over a dipole’s antenna’s peak gain. To avoid confusion, you almost always see an antenna gain written as 3 dBi (for isotropic) or 3 dBd (for dipole). The dBd number is always 2.15 dB less than the dBi number.Dipole antenna pattern CC-BY-SA 3.0
Another thing to consider when thinking about antennas is direction. For example, a dipole’s gain is 1.64:1 (2.15 dBi) peak. But in some directions, it is much less. You can see the radiation pattern for a dipole in the figure to the right. An isotropic pattern would be a perfect sphere.Crash Course on Logs and dB Math
If your math is a bit rusty, you might want a quick review of logarithms.
For decibels, you’ll need base 10 logarithms so that’s all we’ll talk about. Consider the number 100:
- 10 squared (that is 10 to the second power) is 100, so the logarithm of 100 is 2
- The log of 1000 is 3 (because 10 to the 3rd power is 1000)
- The log of 10 is 1
- Any number raised to the 0 power equals 1, so the log of 1 is 0
- We can talk about the antilog which is the reverse operation, so the antilog of 2 is 100 (essentially, to take the antilog of X, you find 10 to the X power)
Logarithms are handy when you have a large range of numbers because it compresses things. There are also some handy math facts that you’ll need to know if you want to do more than just memorize the decibel formula. Adding two logs is like multiplying the two original numbers and taking the log:
- 100×10=1000 and the log of 1000 is 3
By the way, this is how slide rules (like the ones below) work.
What’s even more important, is how easy it is to raise a number to a power using logarithms. Suppose you want to find 20 to the 9th power (written as 20^9). You could multiply 20 by itself, of course. But you can also find the answer by taking the log of 20 (about 1.3) and multiplying by 9. The answer will be the same as log (20^9).
You’ll see that the formula used for decibels will sometimes use a factor of 10x (converting bels to decibels) and sometimes 20x (a combination of the 10x and squaring the ratio). Why? Remember that the bel is a measure power ratio. If you just want to remember a rule of thumb, the formula (see below) with the 10 in it is for power and the one with 20 in it is for voltage or current ratios. Why? Keep reading.Ratios and Reference Values
In simple terms, then, a bel is just the logarithm of the ratio of output power to input power. So if you put in 1 watt and get out 10 watts, that’s a gain of 10X and that’s 1 bel. But like I said, no one uses bels, so multiply the answer by 10 to get decibels (10dB).
That’s all there is to know, right? Not quite. There are two other things to think about. First, what if you are measuring voltage instead of power? The decibel is a power measurement, but you know that power is proportional to voltage squared. So if you take the voltage ratio, you have to multiply the computed value by 2 because multiplying the value by 2 is like squaring the ratio and then taking the log. Since you still have to multiply by 10, the result is you multiply your bel value by 20 instead of 10 if it is refering to a voltage or current ratio..
- When dealing with power dB=10*log(output/input)
- When dealing with voltage or current dB=20*log(output/input)
However, there is one more catch: many times you hear a dB measurement applied to a single value. How can you measure one value and get a ratio? The answer is: you can’t. When you see a single value that appears in dB it means there is an assumed reference value. Sometimes this is made explicit and sometimes it is just implied. For example, if you see a measurement of 5 dBm, this means the measurement is relative to 1 milliwatt. In audio work, you may encounter the dBu or dBv which is relative to .775 VRMS. That’s the voltage that delivers roughly a milliwatt into a 600 ohm load.
Think about the math behind this. For the example of 5 dBm, 5=10*log(output/.001). A little algebra will tell you that the output, then, is about 3.16 mW. 20 dBm is 100 mW. You’ll sometimes see dBV which is referenced to 1 volt RMS.Back to Basics
If you only take away two things from this about decibels, let it be these two:
- Use 10 for power and 20 for amplitudes
- Always ask yourself what are the two parts of the ratio being expressed.
If you keep those in mind, decibels are pretty easy to handle.
These days you can do some pretty complicated things with integrated circuits. It is easy to lose sight of the basics given all this complexity. While the decibel isn’t going to allow you to build anything new, it is useful to understand how it works for everything from filter insertion loss to attenuation in fiber optics (usually represented by dB/m or decibels per meter).
There are many other basic topics that you may gloss over these days or perhaps forgot from some long-ago class. Sometimes it is worthwhile to go read a fundamental book. Or revisit control theory. Either way, going back over old ground with more experience often gives you some new insights.
Filed under: Engineering, Hackaday Columns
[Jochen Alt]’s Paul is one of the coolest robots of its type, and maybe one of the coolest robots period. Personality? Check. Omniwheels? Check. Gratuitous feats of derring-do? Check. Paul is a ball balancing robot.
Under the hood, Paul isn’t all that strange. He’s got two microcontrollers, one for taking care of the balancing and kinematics, and another that handles the LEDs, speech processor, loudspeaker, remote-control, and other frilly bits. But the mathematics! Paul is a cylinder standing up on top of a bowling ball, so the only way it can roll forwards is to lean forwards. But of course, it can’t lean too much, because it has also got to balance. It’s absolutely the least reasonable means of locomotion. We love it.
[Jochen] was nice enough to put everything up on GitHub, so you can see how it was done, even though it looks like magic. And we dare you to watch the video, embedded below, and not feel at least a pang of sympathy pain when (spoiler alert!) he falls flat on his face. Does he recover? We’d love to know!
Paul is just one of the stellar robots in the 2017 Hackaday Sci-Fi contest, so head on over there if you still don’t have your fill.
Filed under: robots hacks
If you know where to go on the Internet, you can pick up an FTDI USB to Serial adapter for one dollar and sixty-seven cents, with free shipping worldwide. The chip on this board is an FTDI FT232RL, and costs about two dollars in quantity. This means the chips on the cheap adapters are counterfeit. While you can buy a USB to serial adapter with a legitimate chip, [Syonyk] found a cheaper solution: buy the counterfeit adapters, a few genuine chips, and rework the PCB. It’s brilliant, and an excellent display of desoldering prowess.
Why is [Syonyk] replacing non-genuine chips with the real FTDI? The best reason is FTDIgate Mk. 1, where the official FTDI driver for Windows detected non-genuine chips and set the USB PID to zero. This bricked a whole bunch of devices, and was generally regarded as a bad move. FTDIgate Mk. 2 was a variation on a theme where the FTDI driver would inject garbage data into a circuit if a non-genuine part was found. This could also brick devices. Notwithstanding driver issues, the best reason for swapping out fake chips for real ones is the performance at higher bit rates; [Syonyk] is doing work at 3 Mbps, and the fake chips just don’t work that fast.
To replace the counterfeit chip, [Syonyk] covered the pins in a nice big glob of solder, carefully heated both sides of the chip, and slid the offending chip off when everything was molten. A bit of solder braid, and the board was ready for the genuine chip.
With the new chip, the cheap USB to serial adapter board works perfectly, although anyone attempting to duplicate these efforts might want to look into replacing the USB mini port with a USB micro port.
Filed under: repair hacks, slider
Popular Electronics was famous for the article introducing the Altair 8800 back in 1975 (well, the cover date was 1975; it really came out in late 1974). That was so popular (no pun intended), that they ran more computer construction articles, including the SWTPC 680 late in 1975. But in 1976 a very popular article ran on building a very simple computer called the COSMAC ELF. [Youtubba] had an Altair, but always wanted a “cute” COSMAC ELF. Now, forty-something years later, he finally got around to it. He made the very detailed video about his experience, below.
Surprisingly, he didn’t have to look very hard for too many of the components as most of them were available from Digikey. He had to get compatible RAM chips, the 1802 CPU and LED displays. He also couldn’t find a look-alike crystal, so he used a fake one and a hidden oscillator. The result looks awfully close to the original. He even did a nice front panel using Front Panel Express.
It might be hard to understand why people got excited over a little computer with a handful of switches. Consider the Altair, though. For $439 you got a very basic machine with 256 bytes of RAM (upgradable to 1K, or beyond if you bought more boards). If you wanted to expand it to something really useful with RAM, disk drives, and a terminal you were still talking lots of cash. And that was 1975 cash. In equivalent terms, that Altair kit would cost $2000 today.
The ELF, on the other hand, could be put together on a piece of perf board. If you had to buy everything from scratch, it might cost $100 back then. If you had a well-stocked junk box, you could cut that down a good bit. The DMA onboard the 1802 chip made the front panel simple, and it facilitated a companion graphics chip that produced crude black and white graphics on a monitor or TV.
Filed under: Microcontrollers
Despite the implementation of the National Do Not Call Registry in the US (and similar programs in other countries), many robocallers still manage to get around the system. Whether they’re operating outside the law somehow (or they simply don’t care about it) there are some ways you can take action to keep these annoying calls from coming through. [Alex] is among those to take matters into his own hands and built a specialty robocall-blocking device.
Based on a Raspberry Pi, the “Banana Phone” is able to intercept incoming calls on standard land lines or VoIP phones. After playing a short message, the caller is asked to input a four-digit code. Once the code is correctly entered, the caller is presumed to be human, added to a whitelist, and then the Pi passes them on to the recipient. There are, however, some legitimate robocallers such as emergency services regarding natural disasters or utility companies regarding outages. For these there is a global whitelist that the Pi checks against and forwards these robocalls on to the recipient automatically.
This project was originally an entry into a contest that the Federal Trade Commission put on a few years ago for ideas about how to defend against robocalls. We covered it back then, but now there are full build instructions. Even though the contest is long over, the Banana Phone is still in active development so if you have a spare Pi lying around you can still set this up yourself. There are some other interesting ways to defend against robocalls as well, like including the “line disconnected” tone in your voicemail, for example.
Filed under: phone hacks
Training machines to effectively complete tasks is an ongoing area of research. This can be done in a variety of ways, from complex programming interfaces, to systems that understand commands in natural langauge. A team from MIT’s Computer Science and Artificial Intelligence Laboratory (CSAIL) wanted to see if it was possible for humans to communicate more directly when training a robot. Their system allows a user to correct a robot’s actions using only their brain.
The concept is simple – using an EEG cap to detect brainwaves, the system measures a special type of brain signals called “error-related potentials”. Simply noticing the robot making a mistake allows the robot to correct itself, and for a nice extra touch – blush in embarassment.
This interface allows for a very intuitive way of working with a robot – upon noticing a mistake, the robot is able to automatically stop or correct its behaviour. Currently the system is only capable of being used for very simple tasks – the video shows the robot sorting objects of two types into corresponding bins. The robot knows that if the human has detected an error, it must simply place the object in the other bin. Further research seeks to expand the possibilities of using this automatic brainwave feedback to train robots for more complex tasks. You can read the research paper here.
MIT’s CSAIL work on lots of exciting projects – their video microphone technology is truly astounding.
[Thanks to Adam Connor-Simmons for the tip!]
Filed under: robots hacks
[Hales] has been on a mission for a while to make his own diodes and put them to use and now he’s succeeded with diodes made of sodium bicarbonate and water, aluminum tape and soldered copper. By combining 49 of them he’s put together a soda bicarb diode steering circuit for a 7-segment display capable of showing the digits 0 to 9.
He takes the idea for his diode from electrolytic capacitors. A simple DIY electrolytic capacitor has an aluminum sheet immersed in a liquid electrolyte. The aluminum and the conductive electrolyte are the two capacitor plates. The dielectric is an aluminum oxide layer that forms on the aluminum when the correct polarity is applied, preventing current flow. But if you reverse polarity, that oxide layer breaks down and current flows. To [Hales] this sounded like it could also act as a diode and so he went to work doing plenty of experiments and refinements until he was confident he had something that worked fairly well.
In the end he came up with a diode that starts with a copper base covered in solder to protect the copper from his sodium bicarbonate and water electrolyte. A piece of aluminum tape goes on top of that but is electrically insulated from it. Then the electrolyte is dabbed on such that it’s partly on the solder and partly on the aluminum tape. The oxide forms between the electrolyte and the aluminum, providing the diode’s junction. Connections are made to the soldered copper and to the aluminum.
To truly try it out he put together a steering circuit for a seven segment display. For that he made a matrix of his diodes. The matrix has seven columns, one for each segment on the display. Then there are ten rows, one for each digit from 0 to 9. The number 1, for example, needs only two segments to light up, and so for the row representing 1, there are only two diodes, i.e. two dabs of electrolyte where the rows overlap the columns for the desired segments. The columns are permanently wired to their segments so the final connection need only be made by energizing the appropriate row of diodes. You can see [Hales] demonstrating this in the video below the break.
One problem [Hales] has found is that the diodes are a bit slow, due to their capacitive nature, but there’s nothing he can do about that. However, another problem that he has attempted to solve but has yet to come up with a solution for is that the dabs of electrolyte dry out and need to be carefully rewetted. So while this isn’t a method for permanent diodes yet, we admire [Hales]’s persistence and inventiveness and if he keeps at it he’ll no doubt find a solution.
In the meantime, check out his previous experiments with copper oxide diodes. And if you want to see a steering circuit made with conventional diodes then we’ve previously talked about [Fran]’s circuit using a 555 and a 4017B decade counter to make a display count down to 0.
Filed under: chemistry hacks
As if you needed any reason other than “just for the heck of it” to hack into a gadget that you own, it looks like nearly all of the GSM-to-IP bridge devices make by DBLTek have a remotely accessible “secret” backdoor account built in. We got sent the link via Slashdot which in turn linked to this story on Techradar. Both include the scare-words “Chinese” and “IoT”, although the devices seem to be aimed at small businesses, but everything’s “IoT” these days, right?
What is scary, however, is that the backdoor isn’t just a sloppy debug account left in, but rather only accessible through an elaborate and custom login protocol. Worse still, when the company was contacted about the backdoor account, they “fixed” the problem not by removing the account, but by making the “secret” login procedure a few steps more complicated. Which is to say, they haven’t fixed the problem at all.
This issue was picked up by security firm Trustwave, but they can’t check out every device on the market all the time. We may be preaching to the choir here, but if you’re ever wondering why it’s important to be able to break into stuff that you own, here’s another reminder.
Filed under: news