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June 21 2018

Desktop Radio Telescope Images The WiFi Universe

It’s been a project filled with fits and starts, and it very nearly ended up as a “Fail of the Week” feature, but we’re happy to report that the [Thought Emporium]’s desktop WiFi radio telescope finally works. And it’s pretty darn cool.

If you’ve been following along with the build like we have, you’ll know that this stems from a previous, much larger radio telescope that [Justin] used to visualize the constellation of geosynchronous digital TV satellites. This time, he set his sights closer to home and built a system to visualize the 2.4-GHz WiFi band. A simple helical antenna rides on the stepper-driven azimuth-elevation scanner. A HackRF SDR and GNU Radio form the receiver, which just captures the received signal strength indicator (RSSI) value for each point as the antenna scans. The data is then massaged into colors representing the intensity of WiFi signals received and laid over an optical image of the scanned area. The first image clearly showed a couple of hotspots, including a previously unknown router. An outdoor scan revealed routers galore, although that took a little more wizardry to pull off.

The videos below recount the whole tale in detail; skip to part three for the payoff if you must, but at the cost of missing some valuable lessons and a few cool tips, like using flattened pieces of Schedule 40 pipe as a construction material. We hope to see more from the project soon, and wonder if this FPV racing drone tracker might offer some helpful hints for expansion.

Learn Something About Phase Locked Loops

The phase locked loop, or PLL, is a real workhorse of circuit design. It is a classic feedback loop where the phase of an oscillator is locked to the phase of a reference signal using an error signal in the same basic way that perhaps a controller would hold a temperature or flow rate in a physical system. That is, a big error will induce a big change and little errors induce little changes until the output is just right. [The Offset Volt] has a few videos on PLLs that will help you understand their basic operation, how they can multiply frequencies (paradoxically, by dividing), and even demodulate FM radio signals. You can see the videos below.

The clever part of a PLL can be found in how it looks at the phase of two signals. For signals to be totally in phase, they must be at the same frequency and also must ebb and peak at the same point. It should be clear that if the frequency isn’t the same the ebbs and peaks can’t line up for any length of time. By detecting how much the signals don’t line up, an error voltage can be generated. That error voltage is used to adjust the output oscillator so that it matches the reference oscillator.

Of course, it wouldn’t be very interesting if the output frequency had to be the same as the reference frequency. The clever trick comes by dividing the output frequency. For example, a 100 MHz crystal oscillator is difficult to design. But taking a voltage-controlled oscillator at 100 MHz (nominal) and dividing its output by 100 will give you a signal you can lock to a 1 MHz crystal oscillator which is, of course, trivial to build.

The real detail lies in the phase comparison and the loop filtering, something that will make more sense once you have watched the videos.

Based on video views, [The Offset Volt] may be the best YouTube channel people aren’t watching much. The videos are clear an easy to understand! He’s even worked in a reference to a self-sealing stem bolt, so we can’t help but be impressed with that.

Our resident video star [Bil Herd] did a talk on PLLs a good while back. If you’d rather read and want to see how a PLL works in software, we’ve talked about that, too.

June 20 2018

Trackball Gets Bolt-On Button Upgrade

The question of whether to use a mouse versus a trackball is something of a Holy War on the level of Vi versus Emacs. We at Hackaday want no part of such things, use whatever you want, and leave us out of it. But we will go as far as to say that Team Trackball seems to take things mighty seriously. We’ve never met a casual trackball user: if they’ve got a trackball on their desk then get ready to hear all about it.

With that in mind, the lengths [LayeredDesigns] went to just to add a couple extra buttons to his CST trackball make a bit more sense. Obviously enamored with this particular piece of pointing technology, he designed a 3D printed “sidecar” that you can mount to the left side of the stock trackball. Matching the shape of the original case pretty closely, this add-on module currently hosts a pair of MX mechanical keys, but the plans don’t stop there.

[LayeredDesigns] mentions that all the free room inside the shell for this two-button modification has got him thinking of what else he could fit in there. The logical choice is a Teensy emulating a USB HID device, which could allow for all sorts of cool programmable input possibilities. One potential feature he mentioned was adding a scroll wheel, which the Teensy could easily interface with and present to the operating system.

We’ve seen our fair share of 3D printed keyboards and keyboard modifications, but we can’t say the same about the legendary trackball. Ones made of cardboard, sure. Pulled out of a military installation and hacked to add USB? You bet. This project is just more evidence of what’s possible with a 3D printer, a caliper, and some patience.

[via /r/functionalprint]

This Weekend: The East Coast RepRap Festival

Are you around Philly, Baltimore, or DC, and looking for something fun to do this weekend? Great news, because Saturday sees the start of the first inaugural East Coast RepRap Festival in Bel Air, Maryland. Eh, we’ll grab some Bohs and boil up some crabs. It’ll be a great time.

Regular readers of Hackaday should have heard of MRRF, the Midwest RepRap Festival, and the greatest 3D printer convention on the planet. There’s a reason it’s so good: it’s not a trade show. It’s simply everyone in the business and a ton of cool people heading out to the middle of Indiana one weekend per year and simply dorking out. All the heavy hitters were at MRRF last year, from [Prusa], to E3D, to [Brook] of Printrbot. The 3D Printing YouTubers made it out, and the entire event was simply a thousand or so people who were the best at what they do just hanging out.

Want evidence a highly unorganized conference of 3D printing enthusiasts can be great? Here’s a working MakerBot Cupcake. Here’s full-color printing with cyan, magenta, yellow, black, and white filament. How about an infinite build volume printer? There are roundtables, demos, and talks. This is the state of 3D printing, and it inexplicably happens in the middle of nowhere every year.

This weekend, the East Coast RepRap Festival is launching. This is not an event organized by SeeMeCNC, the hosts of the Midwest RepRap Festival. This is an independent event, and we have no idea how it’s going to turn out. That said, the schedule of events looks great with 3D printed pinewood (douglasfirfill?) derbies, and of course, the event space will be filled with strange and exotic homebuilt printers. The big names will be there, and it looks like this may be the beginning of something great.

Hackaday is going to have some boots on the ground this weekend, and we’re going to be showing off the greatest and the best from ERRF. Tickets are still available, and it looks like this is shaping up to be a great weekend.

A CNC Plasma Cutter Table, From The Shop Floor Up

Some projects are simple, some focus on precision and craftsmanship, and some are more of the quick-and-dirty variety. This home-built CNC plasma cutter table seems to follow a “go big or go home” philosophy, and we have to say we’re mighty impressed by the finished product.

For those who follow [Bob]’s “Making Stuff” YouTube channel, this build has been a long time coming. The playlist below has eight videos that cover the entire process from cutting the first tubes of the welded frame to the initial test cuts with the finished machine. [Bob] took great pains to make the frame as square and flat as possible, to the extent of shimming a cross member to correct a 0.030″ misalignment before welding. He used good-quality linear rails for each axis, and hefty NEMA 23 steppers. There were a few false starts, like the water pan that was going to be welded out of five separate pieces of steel until the metal shop guys saved the day with their press brake. In the end, the machine turned out great; with a build cost of $2000 including the plasma cutter it’s not exactly cheap, but it’s quite a bargain compared to similar sized commercial machines.

We think the video series is a great guide for anyone looking to make a CNC plasma table. We’ve seen builds like this before, including [This Old Tony]’s CNC router. Watching these builds gives us the itch to get into the shop and start cutting metal.

Hexabitz, Modular Electronics Made Easier

Over the years there have been a variety of modular electronic systems allowing the creation of complex circuits by the interconnection of modules containing individual functions. Hexabitz, a selection of interlocking polygonal small PCBs, is just such a system. What can it bring to the table that others haven’t done already?

The problem facing designers of modular electronics is this: all devices have different requirements and interfaces. To allow connection between modules that preserves all these connections requires an ever-increasing complexity in the inter-module connectors, or the application of a little intelligence to the problem. The Hexabitz designers have opted for the latter angle, equipping each module with an STM32 microcontroller that allows it to identify both itself and its function, and to establish a mesh network with other modules in the same connected project. This also gives the system the ability to farm off computing tasks to individual modules rather than relying solely upon a single microcontroller or single-board computer.

An extremely comprehensive array of modules can be had for the system, which lends it some interesting possibilities, however, it suffers from the inherent problem of modular electronic systems, that it is less easy to incorporate non-standard functions. If they can crack a prototyping module coupled with an easy way to tell its microcontroller to identify whatever function is upon it, they might have a winner.

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Analog Discovery 2 as a Vector Network Analyzer

A while back, I posted a review of the Analog Discovery 2, which is one of those USB “do everything” instruments. You might recall I generally liked it, although I wasn’t crazy about the price and the fact that the BNC connectors were an extra item. However, in that same post, I mentioned I’d look at the device’s capabilities as a network analyzer (NA) sometime in the future. The future, as they say, is now.

What’s an NA?

In its simplest form, there’s not much to an NA. You sweep a frequency generator across some range of frequencies. You feed that into some component or network of components and then you measure the power you get out compared to the power you put in. Fancy instruments can do some other measurements, but that’s really the heart of it.

The output is usually in two parts. You see a scope-like graph that has the frequency as the X-axis and some sort of magnitude as the Y-axis. Often the magnitude will be the ratio of the output power to the input power as a decibel. In addition, another scope-like output will show the phase shift through the network (Y-axis) vs frequency (X-axis). The Discovery 2 has these outputs and you can add custom displays, too.

Why do you care? An NA can help you understand tuned circuits, antennas, or anything else that has a frequency response, even an active filter or the feedback network of an oscillator. Could you do the same measurements manually? Of course you could. But taking hundreds of measurements per octave would be tedious and error-prone.

Set Up

The software setup is easy and works like all the other functions on the Discovery 2. You create a “network” instrument and the most common settings you’ll want to adjust are along the top. You can select a linear or log scale on the X-axis. You also can pick the minimum and maximum sweep frequency, along with the number of samples to take. Along the right, you can select the voltage output of the wave generator, if you care. You can also set the Y-axis units along with the gain on the channels.

The device works by connecting the scope’s channel 1 probe to the input of the device under test and then connecting channel 2 to the output. The input of the device also connects to the wave generator output and you will want to make sure all the grounds are wired together, too. You can see the Digilent video on how to use this mode of the device at the end of this post.

Start Simple

The simplest interesting thing you could look at would be a capacitor. However, this shows a few of the flaws of the Discovery 2. The way the flying leads are set up, it is pretty hard to make good connections for something like this. The BNC accessory would be a little easier. At least it would allow for more types of test leads to easily attach. I elected to put some wires into the flying leads and connect the wires to a breadboard.

The obvious problem with that is the breadboard has its own capacitance along with some crosstalk. With an open circuit, you ought to get a flat line of 0 dB for the reference signal (green in the screenshot above) and more or less negative infinity on the blue trace which is the signal through the test network. As you can see, however, the signal starts to curve around 3 MHz and really has problems at 10 MHz. I do not think this is inherent in the instrument, but a byproduct of the poor test leads and the effects of the solderless breadboard.

Here’s a 10 pF capacitor’s curve:

I assume the little bump at 60 Hz is an artifact of noise from the AC power line either conducted through the USB cable or picked up from the air. The device comes with a USB cable that has an integrated ferrite core but I used whatever happened to be hanging off my computer, so that may explain that.

You can see the response is what you’d expect from a capacitor. High loss at low frequencies, getting better until it levels off at some higher frequency. Note the left side of the graph is at 10 Hz. The instrument is noticeably slow making readings at that frequency. It appears it waits for a certain number of cycles, not a certain period of time, so the reading gets faster as the sweep frequency increases. If you accidentally enter mHz instead of MHz into of the boxes, you will get millihertz and very long runtimes indeed. An important lesson.


Next, I put a 100 uH inductor in place of the capacitor. This doesn’t look like you would expect unless you realize that the inductor is going to resonate with the parasitic capacitance from the breadboard and the leads. Here’s the plot:

The peak is about 2.5 MHz so you can calculate that the test setup has just under 41 pF of stray capacitance. That ignores the effect of stray inductance, but with this setup, I think it is fair to assume that will be relatively small at these frequencies. From the shape of the peak, the capacitance is mostly in series because the signal is making it through. Good to know. However, if you ignore the peak, you can see the expected inductor behavior of dropping as frequency increases.

By the way, pumping a volt through the inductor at resonance causes a large spike which messes up the plot. The instrument protects itself and shows a message that it is out of range. The answer is to turn down the wave’s output voltage on the right-hand panel.

I next put 20 pF across the inductor. In theory, this should resonate at about 3.56 MHz. That doesn’t account for the extra capacitance or the tolerance of the components, for that matter.  The real figure worked out to about 3.4 MHz, as you can see below.

Note, you can still see the spurious series spike, but it has also changed frequency due to the additional capacitance introduced.

Crystal Method

For fun, I took all the other components out and grabbed a colorburst crystal from an old-style TV.  You can see from the figure below that the series peak is right on the money for frequency. Notice the frequency is close, but different, where it is in parallel resonance. That’s why when you specify a crystal, you have to call out if you are looking for the series or parallel resonant frequency.

Just for Fun

Because the NA is such a simple layout and since the NA uses the scope and waveform leads, I thought it would be interesting to manually set the frequency generator and look at the scope without relying on the NA instrument itself. You can see in the video below that it is satisfying to watch the response change with frequency.  I set the sweep to take five seconds to make it easier to watch.

Notice that the blue FFT spike gets bigger as it moves toward resonance. You can also see the scope trace get bigger. Note that the blue oscilloscope trace is on a more sensitive scale than the yellow source trace. They are not close to the same magnitude despite appearances. Also remember that voltage on the scope doesn’t translate directly into power. A 5 V signal at 1 A has more power than a 10 V signal at 10 mA.


I only looked at a few passive examples, but you could use this device to measure antennas, active filters, or anything with a frequency response. Just be careful with grounds and not to put out too much signal for the device under test. You may have noticed that while you get magnitude and phase information, you don’t get some measurements you’d expect on a very pricey instrument made just for this purpose (like VSWR).

Is the Discover 2’s NA mode useful? Yes. Is it perfect? No. The interconnect issue gets more and more problematic the higher you go in frequency. If you already have one of these, by all means, use the NA, especially for lower frequency work. But if you really need an NA, this probably isn’t going to be your first choice.

There are network analyzers out there that are affordable although they may have odd frequency ranges. For example, we recently saw one for $150 that won’t go below 137 MHz. It will, however, go up to 2.4 GHz. If you want more background, we had an article on this whole class of devices before. You might also enjoy Digilent’s video on how to set up the network analyzer, below.

Friday Hack Chat: Ladyada on Creative and Interactive Robotics

Somewhere at the intersection of microcontrollers, open source toolchains, the Maker Movement, and the march of technology, there’s a fuzzy concept that can best be described as robotics or physical computing. Instead of a computer in a box or a dumb microcontroller, these projects interact with the outside world. Whether that’s through the Internet, tapping a bunch of sensors, or just waving the arm of a servo around, there’s a need for a platform that actually does all of this stuff. For this week’s Hack Chat, we’re going to be talking all about creative and interactive robots, and you’re invited.

Our guest for this week’s Hack Chat will be Limor “Ladyada” Fried, the founder of Adafruit, and someone who needs no introduction but we’re going to do it anyway. Adafruit began as a weird side project selling exact reproductions of the Roland TB-303, building cell phone jammers, and making guides to build your own USB power bank before USB power banks were a thing. This has grown into Adafruit, a company with over 100 employees in the heart of New York City, one of the best places for learning and making electronics, and a place that does everything Open Source with zero loans or VC money. By any objective measure, Adafruit has become the most successful business story to come out of the Maker Movement, however nebulously that can be defined.

This week the Hack Chat will be focused on the CRICKIT, the Creative Robotics and Interactive Construction Kit. The CRICKIT is an add-on to Adafruit’s Circuit Playground that allows you to build your own robot with CircuitPython, MakeCode, or just Arduino. There’s support for arts, crafts, sensors, audio, animatronics, physical computing, kinetic sculptures, science experiments, and just about anything else you can think of. Need an example? Here’s Blue Öyster Cult. Here’s that robot that came with the NES. It’s all great fun.

You are, of course, encouraged to add your own questions to the discussion. You can do that by leaving a comment on the Hack Chat Event Page and we’ll put that in the queue for the Hack Chat discussion.join-hack-chat

Our Hack Chats are live community events on the Hackaday.io Hack Chat group messaging. This week is just like any other, and we’ll be gathering ’round our video terminals at noon, Pacific, on Friday, June 22nd.  Here’s a clock counting down the time until the Hack Chat starts.

Click that speech bubble to the right, and you’ll be taken directly to the Hack Chat group on Hackaday.io.

You don’t have to wait until Friday; join whenever you want and you can see what the community is talking about.

Print Physical Buttons for Your Touch Screen

Modern handheld gaming hardware is great. The units are ergonomic powerhouses, yet many of us do all our portable gaming on a painfully rectangular smartphone. Their primary method of interaction is the index finger or thumbs, not a D-pad and buttons. Shoulder triggers have only existed on a few phones. Bluetooth gaming pads are affordable but they are either bulky or you have to find another way to hold your phone. Detachable shoulder buttons are a perfect compromise since they can fit in a coin purse and they’re cheap because you can make your own.

[ASCAS] explains how his levers work to translate a physical lever press into a capacitive touch response. The basic premise is that the contact point is always touching the screen, but until you pull the lever, which is covered in aluminum tape, the screen won’t sense anything there. It’s pretty clever, and the whole kit can be built with consumables usually stocked in hardware stores and hacker basements and it should work on any capacitive touch screen.

Physical buttons and phones don’t have to be estranged and full-fledged keyswitches aren’t exempt. Or maybe many capacitive touch switches are your forte.

Teardown: Box of Pain (Gom Jabbar Sold Separately)

I immediately felt uncomfortable when I realized this thing is called the “Breo iPalm520 Acupressure Hand Massager”. You’re supposed to stick your hand into it, and through unknown machinations it performs some kind of pressure massage complete with heating action. It’s like one of those pain boxes from Dune. It’s all the more disturbing when you realize the red button on the thing is an emergency release. That’s right, once your hand is in this contraption you can’t take it out until the thing has had its way with you or you tap out.

Press to administer the Gom Jabbar

At least once a week I try to get to the local thrift store to look for interesting things. I’d like to be more specific than “interesting things”, but truth be told, I never really know what I’m looking for until I see it. Sure there’s the normal consumer electronics kind of stuff, but I’ve also found some very nice laboratory equipment, computer parts, software, technical books, etc. You just have to go regularly and keep an eye out for the occasional needle amongst the hay.

I want you to know, Dear Readers, that I did briefly summon the courage to put my hand into this thing and turn it on. Now I am not what one might call an overly brave man, and perhaps that might explain my personal experience. But when it started to hum and heat up, constricting around my hand to the point I couldn’t move my fingers, I screamed like a child and mashed the emergency button as if I was a pilot trying to eject from a mortally wounded aircraft. As far as Frank Herbert is concerned, I’m no human at all.

In an effort to better understand this torture device, lets open it up and see what lurks beneath that futuristic exterior.


David Lynch never let us look inside the box, but this is real life and I can do what I want. It’s a fair bet that, the sleeker something looks, the harder it will be to take apart without destroying it. The iPalm520 fits that description perfectly. After you locate the screws, which were naturally recessed so far into the device that I had to go dig out the long-reach drivers I never use, you still have to split the case open. The clips used to hold it together are so strong I was sure the thing would crack before I could get it apart. In fact, I did break several of the clips, despite my best efforts.

With the case opened, we can immediately see the device is pneumatic in nature. An air pump can be observed, as well as some tubing and valves. But before we get into that, let’s look at that control board on the left.


The brains of the iPalm520 are pretty straightforward. There’s only one chip that runs the whole show, directly connected to both the LCD display and the bank of transistors that do the heavy lifting on the motor and valve outputs. The chip itself was expertly wiped of any identifying information; while I can see there used to be something written on it, even under the microscope there’s nothing I can make out.

Not much to be said about the electronics, and little that could practically be salvaged. The LCD image is very nice, but much like the main chip, there’s unfortunately no identifying marks to determine who makes it or to look up any documentation.

Pneumatic Section

This is the real heart of the device, and surely the most interesting part. We can see the air pump which provides pressure to the system, as well as two electromechanical values which are used to selectively inflate different sections of the cuff. There’s also a manual pressure relief valve, which is what gets actuated when you chicken out and press the red button on the top side of the device.

An interesting note is the electrolytic capacitor that was added hastily to the motor. We can only speculate, but it might be that this capacitor was added after it was discovered that the brushed motor was generating too much RF interference.


The air pump has a model number of JQB370, and looking it up online, this seems to be a common overseas part. Running at 6 VDC and capable of 400 mmHg (around 8 Psi), it seems this little pump is commonly used in devices such as blood pressure monitors.

The internal operation is quite fascinating. An offset coupler moves the shaft in an eccentric circle, which flexes three soft rubber bellows. In effect it’s a three cylinder piston pump, but without the complexity of physical pistons, a camshaft, etc. Perfect for lightweight mobile devices.


The two valves used in the device are especially interesting. They are essentially solenoids, with the core being used to block the flow of air through the device. The linear layout, with the air traveling through the coil section, makes for a very compact unit.

The valves strike me as exceptionally well made, and I wouldn’t be surprised if the pair of them were the most expensive element of the entire device. The numbers printed on the valve body don’t seem to correspond to anything I could find online, though a search for “mini solenoid valve” on the usual overseas websites shows very similar products.


Finally, that brings us to the cuff itself. The outer case is exceptionally strong, no doubt to contain the pressure during operation, and according to the markings is made of ABS with 10% glass fiber reinforcement. Four air inlets correspond to four separate air bladders inside the cuff. When combined with the panels of raised rubber shapes these bladders allow the iPalm520 to selectively push different patterns against the user’s hands. While rudimentary in this particular device, pneumatic actuators such as these have applications in soft robotics.

In addition, two connectors lead down into a pocket in the cuff fabric. Here we can find the heating element and temperature sensor. This setup is actually very similar to what was used in the Christmas Laser Projector to maintain laser diode temperature.

Salvaged Parts

While the control board is something of a lost cause, the pneumatic components of this device are absolutely worth harvesting for possible future projects. The air pump and valves are ripe for reuse, and would make an excellent “starter kit” for working with air powered contraptions.

That said, given that the Breo iPalm520 retails for $130 USD, it certainly isn’t worth buying one just for the parts. In the end, this was a perfect thrift store find; it cost me something like $5, and for that price I’m quite pleased. To date my thrift store strategy has yet to fail me: if it’s got buttons and looks cool, it’s probably worth taking apart.

I love writing these teardown articles but I’m often at the mercy of what wacky equipment I happen across. If you have suggestions, or even something you’d like to send in for teardown, let us know on the tips line!

Bunnie Weighs in on Tariffs

[Bunnie] has penned his thoughts on the new 25% tariffs coming to many goods shipped from China to the US. Living and working both in the US and China, [Bunnie] has a unique view of manufacturing and trade between the two countries. The creator of Novena and Chumby, he’s also written the definitive guide on Shenzen electronics.

All the marked items are included in the new tariffs

The new US tariffs come into effect on July 6th. We covered the issue last week, but Bunnie has gone in-depth and really illustrates how these taxes will have a terrible impact on the maker community. Components like LEDs, resistors, capacitors, and PCBs will be taxed at the new higher rate. On the flip side, Tariffs on many finished consumer goods such as cell phone will remain unchanged.

As [Bunnie] illustrates, this hurts small companies buying components. Startups buying subassemblies from China will be hit as well. Educators buying parts kids for their classes also face the tax hike. Who won’t be impacted? Companies building finished goods. If the last screw of your device is installed in China, there is no tax. If it is installed in the USA, then you’ll pay 25% more on your Bill of Materials (BOM). This incentivizes moving assembly offshore.

What will be the end result of all these changes? [Bunnie] takes a note from Brazil’s history with a look at a PC ISA network card. With DIP chips and all through-hole discrete components, it looks like a typical 80’s design. As it turns out the card was made in 1992. Brazil had similar protectionist tariffs on high-tech goods back in the 1980’s. As a result, they lagged behind the rest of the world in technology. [Bunnie] hopes these new tariffs don’t cause the same thing to happen to America.

[Thanks to [Robert] and [Christian] for sending this in]

Would You Look At That Yaw Control

[Jeff Bezos] might be getting all the credit for developing a rocket that can take off and land vertically, but [Joe Barnard] is doing it the hard way. He’s doing it with Estes motors you can pick up in any hobby shop. He’s doing it with a model of a Falcon 9, and he’s on his way to launching and landing a rocket using nothing but solid propellant.

The key to these launches is, of course, the flight controller, This is the Signal flight controller, and it has everything you would expect from a small board meant to mount in the frame of a model rocket. There’s a barometer, an IMU, a buzzer (important!), Bluetooth connectivity, and a microSD card slot for data logging. What makes this flight computer different is the addition of two connectors for standard hobby servos. With the addition of a 3D printed adapter, this flight controller adds thrust vectoring control. That means a rocket will go straight up without the use of fins.

We’ve seen [Joe]’s work before, and things have improved significantly in the last year and a half. The latest update from last weekend was a scale model (1/48) of the Falcon Heavy. In a 45-second video, [Joe]’s model of the Falcon Heavy launches on the two booster rockets, lights the center core, drops the two boosters and continues on until the parachutes unfurl. This would be impressive without active guidance of the motor, and [Joe] is adding servos and launch computers to the mix. It’s awesome, and certainly unable to be exported from the US.

A YouTube Subscriber Counter With A Tetris Twist

When it comes to YouTube subscriber counters, there’s not much wiggle room for creativity. Sure, you can go with Nixies or even more exotic displays, but in the end a counter is just a bunch of numbers.

But [Brian Lough] found a way to jazz things up with this Tetris-playing YouTube sub counter. For those of you not familiar with [Brian]’s channel, it’s really worth a watch. He tends toward long live-stream videos where he works on one project for a marathon session, and there’s a lot to learn from peeking over his virtual shoulder. This project stems from an earlier video, posted after the break, which itself was a condensation of several sessions hacking with the RGB matrix that would form the display for this project. He’s become enamored of the cheap and readily-available 64×32 pixel RGB displays, and borrowing an idea from Mc Lighting author [toblum], he decided that digits being assembled from falling Tetris blocks would be a nice twist. [Brian] had to port the Tetris-ifying code to Arduino before getting the ESP8266 to do the work of getting the subs and updating the display. We think the display looks great, and the fact that the library is open and available means that you too can add Tetris animations to your projects.

None of this is to say that more traditional sub counters can’t be cool too. From a minimalist display to keeping track of all your social media, good designs are everywhere. And adding a solid copper play button is a nice touch too.

Calm Down: It’s Only Assembly Language

Based on [Ben Jojo’s] title — x86 Assembly Doesn’t have to be Scary — we assume that normal programmers fear assembly. Most hackers don’t mind it, but we also don’t often have an excuse to program assembly for desktop computers.

In fact, the post is really well suited for the typical hacker because it focuses the on real mode of an x86 processor after it boots. What makes this tutorial a little more interesting than the usual lecture is that it has interactive areas, where a VM runs your code in the browser after assembling with NASM.

We really like that format of reading a bit and then playing with some code right in the browser. There is something surreal about watching a virtual PC booting up inside your browser. Yeah, we’ve seen it before, but it still makes our eyebrows shoot up a little.

We hope he’ll continue this as a series, because right now it stops after talking about a few BIOS functions. We’d love to see more about instructions, indexing, string prefixes, and even moving to code that would run under Linux or Windows. It would be nice, too, if there was some information about setting up a local environment. Now if you want to make a serious investment and you use Linux, this book is a lot to chew on but will answer your questions.

Of course, there are many tutorials, but this is a fun if brief introduction. If you want to know more about assembly outside the browser, we covered that. If you really want to write a real bootloader, there’s help for that, too.

June 19 2018

Refurbishing A DEC 340 Monitor

Back in the “good old days” movie theaters ran serials. Every week you’d pay some pocket change and see what happened to Buck Rogers, Superman, or Tex Granger that week. Each episode would, of course, end in a cliffhanger. [Keith Hayes] has started his own serial about restoring a DEC 340 monitor found in a scrap yard in Australia. The 340 — not a VT340 — looks like it could appear in one of those serials, with its huge cabinets and round radar-like display. [Keith] describes the restoration as “his big project of the year” and we are anxious to see how the cliffhangers resolve.

He’s been lucky, and he’s been unlucky. The lucky part is that he has the cabinet with the CRT and the deflection yoke. Those would be very difficult to replace. The unlucky part is that one entire cabinet of electronics is missing.

Keep in mind, this monitor dates from the 1960s when transistors were fairly new. The device is full of germanium transistors and oddball silicon transistors that are unobtainable. A great deal of the circuitry is on “system building block” cards. This was a common approach in those days, to create little PC boards with a few different functions and build your circuit by wiring them together. Almost like a macro-scale FPGA with wire backplanes as the programming.

Even if some of the boards were not missing, there would be some redesign work ahead. The old DEC machine used a logic scheme that shifted between ground and a negative voltage. [Keith] wants to have a more modern interface into the machine so the boards that interface with the outside world will have to change, at least. It sounds like he’s on his way to doing a modern remake of the building block cards for that reason, and to preserve the originals which are likely to be difficult to repair.

The cliffhanger to this first installment is a brief description of what one of the system building block cards looks like. The 1575 holds 8 transistors and 11 diodes. It’s apparently an analog building block made to gate signals from the monitor’s digital to analog converters to other parts of the circuit. You’ll have to tune into the next episode to hear more of his explanation.

If you want to read about how such a thing was actually used, DECUS had a programming manual that you can read online. Seeing the round monitor made us think of the old PDP-1 that lives at the Computer History Museum. We are sure it had lots of practical uses, but we think of it as a display for Spacewar.

Laser Cutter Turns Scrapped To Shipped

We’ll go way out on a limb here and say you’ve probably got a ridiculous amount of flattened cardboard boxes. We’re buying more stuff online than ever before, and all those boxes really start to add up. At the least we hope they’re making it to the recycling bin, but what about reusing them? Surely there’s something you could do with all those empty shipping boxes…

Here’s a wild idea…why not use them to ship things? But not exactly as they are, unless you’re in the business of shipping big stuff, the probably won’t do you much good as-is. Instead, why not turn those big flattened cardboard boxes into smaller, more convenient, shippers? That’s exactly what [Felix Rusu] has done, and we’ve got to say, it’s a brilliant idea.

[Felix] started by tracing the outline of the USPS Priority Small Flat Rate Box, which was the perfect template as it comes to you flat packed and gets folded into its final shape. He fiddled with the design a bit, and in the end had a DXF file he could feed into his 60W CO2 laser cutter. By lowering the power to 15% on the fold lines, the cutter is even able to score the cardboard where it needs to fold.

Assuming you’ve got a powerful enough laser, you can now turn all those Amazon Prime boxes into the perfect shippers to use when your mom finally makes you sell your collection of Yu-Gi-Oh! cards on eBay. Otherwise, you can just use them to build a wall so she’ll finally stay out of your side of the basement.

[Thanks to Adrian for the tip.]

Printing Strain Wave Gears

We just wrapped up the Robotics Module Challenge portion of the Hackaday Prize, and if there’s one thing robots need to do, it’s move. This usually means some sort of motor, but you’ll probably want a gear system on there as well. Gotta have that torque, you know.

For his Hackaday Prize entry, [Johannes] is building a 3D printed Strain Wave Gear. A strain wave gear has a flexible middle piece that touches an outer gear rack when pushed by an oval central rotor. The difference in the number of teeth on the flexible collar and the outer rack determine the gear ratio.

This gear is almost entirely 3D printed, and the parts don’t need to be made of flexible filament or have weird support structures. It’s printed out of PETG, which [Johannes] says is slippery enough for a harmonic drive, and the NEMA 17 stepper is completely contained within the housing of the gear itself.

Printing a gear system is all well and good, but what do you do with it? As an experiment, [Johannes] slapped two of these motors together along with a strange, bone-like adapter to create a pan/tilt mount for a camera. Yes, if you don’t look at the weird pink and blue bone for a second, it’s just a DSLR on a tripod with a gimbal. The angular resolution of this setup is 0.03 degrees, so it should be possible to use this setup for astrophotography. Impressive, even if that particular implementation does look a little weird.

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Federico Faggin: The Real Silicon Man

While doing research for our articles about inventing the integrated circuit, the calculator, and the microprocessor, one name kept popping which was new to me, Federico Faggin. Yet this was a name I should have known just as well as his famous contemporaries Kilby, Noyce, and Moore.

Faggin seems to have been at the heart of many of the early advances in microprocessors. He played a big part in the development of MOS processors during the transition from TTL to CMOS. He was co-creator of the first commercially available processor, the 4004, as well as the 8080. And he was a co-founder of Zilog, which brought out the much-loved Z80 CPU. From there he moved on to neural networking chips, image sensors, and is active today in the scientific study of consciousness. It’s time then that we had a closer look at a man who’s very core must surely be made of silicon.

Learning Electronics

Federico at Olivetti, middle-right Federico at Olivetti, middle-right. Photo: intel4004.com

Faggin was born in 1941 in Vicenza, Italy. From an early age, he formed an interest in technology, even attending a technical high school.

After graduating at age 19 in 1961, he got a short-term job at the Olivetti Electronics Laboratory. There he worked on a small experimental digital transistor computer with a 4096 word, 12-bit magnetic core memory and an approximately 1000 logic gate CPU. After his boss had a serious car accident, Faggin took over as project leader. The job was a great learning experience for his future career.

He next studied physics at the University of Padua where he graduated summa cum laude in 1965. He stayed on for a year teaching electronics to 3rd-year students.

Creating MOS Silicon Gate Technology (SGT) At Fairchild

In 1967 he started work at SGS-Fairchild, now STMicroelectronics, in Italy. There he developed their first MOS (metal-oxide-semiconductor) silicon gate technology (SGT) and their first two commercial MOS ICs. They then sent him to Silicon Valley in California to work at Fairchild Semiconductor in 1968.

During the 1960s, logic for ICs was largely done using TTL (Transistor-Transistor Logic). The two ‘T’s refer to using bipolar junction transistors for the logic followed by one or more transistors for the amplification. TTL was fast but took a lot of room, restricting how much could fit into an IC. TTL microprocessors also consumed a lot of power.


On the other hand, ICs containing MOSFETs had manufacturing problems that lead to inconsistent and variable speeds as well as lower speeds than was theoretically possible. If those problems could be solved then MOS would be a good substitute for TTL on ICs since more could be crammed into a smaller space. MOSFETs also required far less power.

In the mid-1960s, to make an aluminum gate MOSFET, the source and drain regions would first be defined and doped, followed by the gate mask defining the thin-oxide region, and lastly the aluminum gate over the thin-oxide.

However, the gate mask would inevitably be misaligned in relation to the source and drain masks. The workaround for this misalignment was to make the thin-oxide region large enough to ensure that it overlapped both the source and drain. But this led to gate-to-source and gate-to-drain parasitic capacitance which was both large and variable and was the source of the speed problems.

Faggin and and the rest of his team at Fairchild worked on these problems between 1966 and 1968. Part of the solution was to define the gate electrode first and then use that as a mask to define the source and gate regions, minimizing the parasitic capacitances. This was called the self-aligned gate method. However, the process for making self-aligned gates raised issues with using aluminum for the gate electrode. This was solved by switching to amorphous silicon instead. This self-aligned gate solution had been worked on but not to the point where ICs could be manufactured for commercial purposes.

Faggin and Tom Klein At Fairchild in 1967 Faggin and Tom Klein At Fairchild in 1967, Credit: Fairchild Camrea & Instrument Corporation

In 1968, Faggin was put in charge of developing Fairchild’s self-aligned gate MOS process technology. He first worked on a precision etching solution for the amorphous silicon gate and then created the process architecture and steps for fabricating the ICs. He also invented buried contacts, a technique which further increased the density through the use of an additional layer making direct ohmic connections between the polysilicon gate and the junctions.

These techniques became the basis of Fairchild’s silicon gate technology (SGT), which was widely used by industry from then on.

Faggin went on to make the first silicon-gate IC, the Fairchild 3708. This was a replacement for the 3705, a metal-gate IC implementing an 8-bit analog multiplexor with decoding logic and one which they had trouble making due to strict requirements. During its development, he further refined the process by using phosphorus gettering to soak up impurities and by substituting the vacuum-evaporated amorphous silicon with polycrystalline silicon applied using vapor-phase deposition.

The resulting SGT meant more components could fit on the IC than with TTL and power requirements were lower. It also gave a three to five times speed improvement over the previous MOS technology.

Making The First Microprocessors At Intel

Intel C4004 Intel C4004 by Thomas Nguyen CC BY-SA 4.0

Faggin left Fairchild to join the two-year-old Intel in 1970 in order to do the chip design for the MCS-4 (Micro Computer System) project. The goal of the MCS-4 was to produce four chips, initially for use in a calculator.

One of those chips, the 4004, became the first commercially available microprocessor. The SGT which he’d developed at Fairchild allowed him to fit everything onto a single chip. You can read all the details of the steps and missteps toward that invention in our article all about it. Suffice it to say that he succeeded and by March 1971, all four-chips were fully functional.

Faggin’s design methodology was then used for all the early Intel microprocessors. That included the 8-bit 8008 introduced in 1972 and the 4040, an improved version of the 4004 in 1974, wherein Faggin took a supervisory role.

Meanwhile, Faggin and Masatoshi Shima, who also worked on the 4004, both developed the design for the 8080. It was released in 1974 and was the first high-performance 8-bit microprocessor.

Creating The Z80

Z80 CPUIn 1974, Faggin left Intel to co-found Zilog with Ralph Ungermann to focus on making microprocessors. There he co-designed the Z80 with Shima, who joined him from Intel. The Z80 was software compatible with the 8080 but was faster and had double the number of registers and instructions.

The Z80 went on to be one of the most popular CPUs for home computers up until the mid-1980s, typically running the CP/M OS. Some notable computers were the Heathkit H89, the Osborne 1, the Kaypro series, a number of TRS-80s, and some of the Timex/Sinclair computers. The Commodore 128 used one alongside the 8502 for CP/M compatibility and a number of computers could use it as an add-on. My own experience with it was through the Dy4.

This is a CPU which no doubt many Hackaday readers will have fond memories of and still build computers around to this day, one such example being this Z80 Raspberry Pi look-alike.

The Z80, as well as the Z8 microcontroller conceived of by Faggin are still in production today.

The Serial Entrepreneur

After leaving Zilog, in 1984, Faggin created his second startup, Cygnet Technologies, Inc. There he conceived of the Communication CoSystem, a device which sat between a computer and a phone line and allowed transmission and receipt of both voice and data during the same session.

In 1986 he co-founded Synaptics along with Carver Mead and became CEO. Initially, they did R&D in artificial neural networks and in 1991, produced the I1000, the first single-chip optical character recognizer. In 1994 they introduced the touchpad, followed by early touchscreens.

Between 2003 and 2008, Faggin was president and CEO of Foveon where he redirected their business into image sensors.

At the Computer History Museum At the Computer History Museum, by Dicklyon CC-BY-SA 4.0

Awards And Present Day

Faggin received many awards and prizes including the Marconi Prize, the Kyoto Prize for Advanced Technology, Fellow of the Computer History Museum, and the 2009 National Medal of Technology and Innovation given to him by President Barack Obama. In 1996 he was inducted into the National Inventor’s Hall of Fame for co-inventing the microprocessor.

In 2011 he and his wife founded the Federico and Elvia Faggin Foundation, a non-profit organization supporting research into consciousness through theoretical and experimental research, an interest he gained from his time at Synaptics. His work with the Foundation is now his full-time activity.

He still lives in Silicon Valley, California where he and his wife moved to from Italy in 1968. A fitting home for the silicon man.

Lawn From Hell Saved by Mower From Heaven

It’s that time of year again, at least in the northern hemisphere. Everything is alive and growing, especially that narrow-leafed non-commodity that so many of us farm without tangible reward. [sonofdodie] has a particularly hard row to hoe—his backyard is one big, 30° slope of knee-ruining agony. After 30 years of trudging up and down the hill, his body was telling him to find a better way. But no lawn service would touch it, so he waited for divine inspiration.

And lo, the answer came to [sonofdodie] in a trio of string trimmers. These Whirling Dervishes of grass grazing are mounted on a wheeled plywood base so that their strings overlap slightly for full coverage. Now he can sit in the shade and sip lemonade as he mows via rope and extension cord using a mower that cost about $100 to build.

These heavenly trimmers have been modified to use heavy nylon line, which means they can whip two weeks’ worth of rain-fueled growth with no problem. You can watch the mower shimmy down what looks like the world’s greatest Slip ‘n Slide hill after the break.

Yeah, this video is two years old, but somehow we missed it back then. Ideas this fresh that tackle age-old problems are evergreen, unlike these plots of grass we must maintain. There’s more than one way to skin this ecological cat, and we’ve seen everything from solar mowers to robotic mowers to mowers tied up to wind themselves around a stake like an enthusiastic dog.

Thanks for the tip, [Itay]!

What is Our Martian Quarantine Protocol?

If you somehow haven’t read or watched War of the Worlds, here’s a spoiler alert. The Martians are brought down by the common cold. You can argue if alien biology would be susceptible to human pathogens, but if they were, it wouldn’t be surprising if aliens had little defense against our bugs. The worrisome part of that is the reverse. Could an astronaut or a space probe bring back something that would ravage the Earth with some disease? This is not science fiction, it is both a historically serious question and one we’ll face in the near future. If we send people to Mars are they going to come back with something harmful?

A Bit of News: Methane Gas Fluctuations on Mars

What got me thinking about this was the mounting evidence that there could be life on Mars. Not a little green man with a death ray, but perhaps microbe-like life forms. In a recent press release, NASA revealed that they not only found old organic material in rocks, but they also found that methane gas is present on Mars and the amount varies based on the season with more methane occurring in the summer months. There’s some dispute about possible inorganic reasons for this, but it is at least possible that the variation is due to increased biological activity during the summer.

These aren’t the first potential signs of life on Mars, either. In 1996, David McKay, Everett Gibson, and Kathie Thomas-Keprta from the Johnson Space Center announced they had found microbial fossils in a piece of meteorite that originated on Mars (see picture, below). The scientific community came up with a lot of alternative explanations, but to this day we don’t know conclusively if it is evidence of Martian life or just an inorganic process.

History Repeats

So far, there’s nothing really worrisome about Martian microbes because they are far away. But we have had contact with one other extraterrestrial body already: the moon. If you think the moon landing was fake, you’ve clearly overestimated the ability of the government to keep a secret. In 1969, two astronauts who had walked on the moon returned to Earth. Would they go down in history as modern-day typhoid Mary’s?

There was a very low chance that the moon harbored any sort of dangerous microbes, but there was a chance. And the price to pay for being wrong could have been very high, so NASA erred on the side of caution. That’s how the Mobile Quarantine Facility (MQF) came into being.

Chillin’ in an RV

If you have ever seen an Airstream trailer, you’d recognize the MQF. It was a 35-foot trailer that had no wheels but did have an elaborate air filtering system. Once the Apollo capsule landed in the ocean, the recovery crew threw down isolation suits the crew put on until they were brought to USS Hornet where they were installed in the MQF.

Although 35 feet doesn’t sound very big for three men, it was spacious compared to the lunar capsule they’d been in. Actually, there were five men inside — an engineer and a doctor were sealed in with the crew for the 65-hour observation period. Carried by airplane and truck, the MQF made its way to Pearl Harbor and then Houston. Once in Houston, the space travelers were released for two more weeks of isolation in the Lunar Receiving Lab.

The same procedure was in place until Apollo 15. Of course, Apollo 13 didn’t reach the moon, so it didn’t use the MQF either. Looking back on it, it seems almost silly that there was so much concern.

Now There’s Mars

It might seem silly now, but back then the logic was sound. First and foremost, if there was any chance at all, you had to be sure. Being wrong would have been devastating — possibly even killing everyone on Earth. Second, this was a well-funded and highly-visible government project so there was some political need to look cautious and a lot of money available to do so.

Mars may be a different story. NASA isn’t funded like it used to be. Elon Musk’s company may get there first, or maybe another country will go. We are at a time when people aren’t as careful as they used to be, in a lot of areas. Will we take precautions against a Martian plague?

Even if you think native Martian life is not likely (or not likely to want to feast on humans and other Earth creatures), there’s another concern. In fact, it may be more likely and more likely to be deadly. It turns out that despite NASA’s unwillingness to go out on a limb and say there is life on Mars, we know that there is almost certainly some life on Mars. We know that because we brought it there ourselves.

Every spacecraft we send to the red planet — or anywhere — will have some amount of Earth life within it. The process even has a name: forward contamination. NASA has a planetary protection officer that ensures the Committee on Space Research (COSPAR) standards are met. This international standard requires that all space exploring nations limit the chance of contamination to 1 in 1,000 total. It even goes as far as to allocate that total to different nations. The US is allowed a 1 in 40,000 chance.

The initial Viking probes were baked almost sterile, but after discovering the harsh environment on the Martian surface, future probes were given more latitude. However, more recent research has shown that on Earth, microbes can live under some hellish conditions, so there is some likelihood we’ve already contaminated Mars.

Don’t think the microbes would survive the ride to Mars? Think again. Experiments on the International Space Station confirm that the cleaning done by NASA leaves only the hardiest strains of bacteria and it appears that at least some could hibernate until they found the right conditions for life. In fact, under current COSPAR rules, if NASA’s Curiosity probe finds water, it can’t get near it because it is not clean enough.

Double Threat

So there are really two threats. Native Martian microbes hitching a ride to Earth, or mutated Earth organisms catching a lift back to their home planet. Either way could have serious consequences. The same COSPAR group that dictates how many microbes you can take to Mars and other planets also specifies how to quarantine things coming back. The United States actually had the “Extra-Terrestrial Exposure Law” at the time of the moon landings, but that was removed in 1991. So it isn’t clear if a private entity like Musk would be required to follow any such procedure.

Of course, this is Hackaday, so what’s the hacker angle to all this? In my opinion, part of the problem here is defining life. What’s alive and what’s not? Like Justice Potter Stewart said about pornography, “I know it when I see it.” On Star Trek it was easy to “scan” a planet and announce you’d found life forms. But what does that mean exactly? There have been cases found of inorganic matter self-organizing. There are macromolecular systems that self-replicate. There is no assurance that alien life would be based on the carbon chemistry we associate with life.

A few decades of scientists haven’t figured that out yet. Maybe its time we took a crack at it. How can you detect life? For safety, how much life do you need to detect? Microbial life? Is it possible that inorganic life (e.g., silicon-based life) would not be harmful to people? Are we sure? Even just determining Earth-like life — preferably over at least a short distance — would be a great benefit to science.  If you want some reading on that topic, stop off at NASA’s astrobiology web site.

All the images in this post are from NASA, as you might expect. If you want to see more about the MQF, Airstream has an interesting video with a few internal details of the facility’s construction. You can see that video, below.

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