How Does A Voltage Multiplier Work?

March 22, 2017 by Manuel Rodriguez-Achach 43 Comments

If you need a high voltage, a voltage multiplier is one of the easiest ways to obtain it. A voltage multiplier is a specialized type of rectifier circuit that converts an AC voltage to a higher DC voltage. Invented by Heinrich Greinacher in 1919, they were used in the design of a particle accelerator that performed the first artificial nuclear disintegration, so you know they mean business.

Theoretically the output of the multiplier is an integer times the AC peak input voltage, and while they can work with any input voltage, the principal use for voltage multipliers is when very high voltages, in the order of tens of thousands or even millions of volts, are needed. They have the advantage of being relatively easy to build, and are cheaper than an equivalent high voltage transformer of the same output rating. If you need sparks for your mad science, perhaps a voltage multiplier can provide them for you.

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Dartboard Watches Your Throw; Catches Perfect Bullseyes

March 22, 2017 by Dan Maloney 61 Comments

Some people really put a lot of effort into rigging the system. Why spend years practicing a skill and honing your technique to hit a perfect bullseye in darts when you can spend the time building an incredibly complicated auto-bullseye dartboard that’ll do it for you?

In fairness, what [Mark Rober] started three years ago seemed like a pretty simple task. He wanted to build a rig to move the dartboard’s bullseye to meet the predicted impact of any throw. Seems simple, but it turns out to be rather difficult, especially when you choose to roll your own motion capture system.

That system, built around the Nvidia Jetson TX1, never quite gelled, a fact which unfortunately burned through the first two years of the project. [Mark] eventually turned to the not inexpensive Vicon Vantage motion capture system with six IR cameras. A retroreflector on the non-regulation dart is tracked by the system and the resulting XY data is fed into MATLAB to calculate the parabolic path of the dart. An XY-gantry using six steppers quickly shifts the board so the bullseye is in the right place to catch the incoming dart.

It’s a huge amount of work and a lot of money to spend, but the group down at the local bar seemed to enjoy it. We wonder if it can be simplified, though. Perhaps tracking just the thrower’s motions with an IMU-based motion capture system and extrapolating the impact point would work.

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Shut The Backdoor! More IoT Cybersecurity Problems

March 22, 2017 by Al Williams 30 Comments

We all know that what we mean by hacker around here and what the world at large thinks of as a hacker are often two different things. But as our systems get more and more connected to each other and the public Internet, you can’t afford to ignore the other hackers — the black-hats and the criminals. Even if you think your data isn’t valuable, sometimes your computing resources are, as evidenced by the recent attack launched from unprotected cameras connected to the Internet.

As [Elliot Williams] reported earlier, Trustwave (a cybersecurity company) recently announced they had found a backdoor in some Chinese voice over IP gateways. Apparently, they left themselves an undocumented root password on the device and — to make things worse — they use a proprietary challenge/response system for passwords that is insufficiently secure. Our point isn’t really about this particular device, but if you are interested in the details of the algorithm, there is a tool on GitHub, created by [JacobMisirian] using the Trustwave data. Our interest is in the practice of leaving intentional backdoors in products. A backdoor like this — once discovered — could be used by anyone else, not just the company that put it there.

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Creepy Speaking Neural Networks

March 22, 2017 by Elliot Williams 37 Comments

Tech artist [Alexander Reben] has shared some work in progress with us. It’s a neural network trained on various famous peoples’ speech (YouTube, embedded below). [Alexander]’s artistic goal is to capture the “soul” of a person’s voice, in much the same way as death masks of centuries past. Of course, listening to [Alexander]’s Rob Boss is no substitute for actually watching an old Bob Ross tape — indeed it never even manages to say “happy little trees” — but it is certainly recognizable as the man himself, and now we can generate an infinite amount of his patter.

Behind the scenes, he’s using WaveNet to train the networks. Basically, the algorithm splits up an audio stream into chunks and tries to predict the next chunk based on the previous state. Some pre-editing of the training audio data was necessary — removing the laughter and applause from the Colbert track for instance — but it was basically just plugged right in.

The network seems to over-emphasize sibilants; we’ve never heard Barack Obama hiss quite like that in real life. Feeding noise into machines that are set up as pattern-recognizers tends to push them to the limits. But in keeping with the name of this series of projects, the “unreasonable humanity of algorithms”, it does pretty well.

He’s also done the same thing with multiple speakers (also YouTube), in this case 110 people with different genders and accents. The variation across people leads to a smoother, more human sound, but it’s also not clearly anyone in particular. It’s meant to be continuously running out of a speaker inside a sculpture’s mouth. We’re a bit creeped out, in a good way.

We’ve covered some of [Alexander]’s work before, from the wince-inducing “Robot Bites Man” to the intellectual-conceptual “All Prior Art“. Keep it coming, [Alexander]!

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Making More Of Me Money

March 22, 2017 by Brian Benchoff 28 Comments

For the last few years, Hackaday has really been stepping up our game with marketing materials. Our t-shirts and swag are second to none, and last year we introduced the ‘Benchoff Buck’ (featured above), a bill replete with Jolly Wrencher EURions that is not yet legal currency. At least until we get a sweet compound in the desert, that is.

[Andrew Sowa] created the Benchoff Nickel. It’s a visage of yours truly emblazoned on a PCB, rendered in FR4, silkscreen, gold, and OSHPark’s royal purple. In doing so, [Andrew] has earned himself a field commission to the rank of lieutenant and can now reserve the dune buggy for a whole weekend.

The Benchoff Nickel was created in KiCad using the Bitmap2Component functionality. Planning this required a little bit of work; there are only five colors you can get on an OSH Park PCB, from white to gold to beige to purple (soldermask on top of copper) to black (soldermask with no copper). Luckily, the best picture we have of me renders very well in five colors.

The Bitmap2Component part of KiCad will only get you so far, though. It’s used mainly to put silkscreen logos on a board, and messing around with copper and mask layers is beyond its functionality. To import different layers of my face into different layers of a KiCad PCB, [Andrew] had to open up Notepad and make a few manual edits. It’s annoying, but yes, it can be done.

OSH Park’s fabs apparently use two different tones of FR4

The Benchoff Nickel can be found on Github and as a shared project on OSH Park ($22.55 for three copies). One little curiosity of the OSH Park fabrication process presented itself with [Andrew]’s second order of Benchoff Nickels. OSH Park uses at least two board houses to produce their PCBs, and one of them apparently uses a lighter shade of FR4. This resulted in a lighter skin tone for the second order of Benchoff Nickels.

This is truly tremendous work. I’ve never seen anything like this, and it’s one of the best ‘artistic’ PCBs I’ve ever held in my hands. It was a really great surprise when [Andrew] handed me one of these at the Hackaday Unconference in Chicago. I’ll be talking to [Andrew] again this week at the Midwest RepRap festival, and we’re going to try and figure out some way to do a small run of Benchoff Nickels.

Edit: OSH Park revealed why there are different tones of FR4. In short, there aren’t. The lighter shade of skintone is actually FR408, which is used on 4-layer boards.

Saturday clock - 1 CPU clock cycle per day

Saturday Clock: An 0.000011574Hz ATtiny85 Clock

March 21, 2017 by Steven Dufresne 40 Comments

In these times when we try to squeeze out extra clock cycles by adding more cores to our CPUs and by enlisting the aid of GPUs, [Ido Gendel] thought it would be fun to go in the exact opposite direction, supply a clock to the ATtiny85 that cycles only once per day, or at 0.000011574Hz. What application could this have? Well, if he could do it in seven instructions or less, how about turning on an LED at sunset Friday evening, to indicate the start of the Jewish Shabbat (Saturday), and turn it off again at sunset Saturday evening.

Notice the subtlety. A clock that cycles once per day means you can execute at most one instruction per day. Luckily on AVR microcontrollers, the instructions he needed can execute in just one cycle. That of course meant diving down into assembly code. [Ido] wasn’t an assembly wizard, so to find the instructions, he compiled C code and examined the resulting assembly until he found what he needed. One instruction turns on the LED and the instruction immediately following turns it off again, which normally would make it happen too fast for the human eye to register. But the instruction to turn it on runs on Friday evening and the very next instruction, the one that turns it off, doesn’t run until Saturday evening. Do you feel like you’re in a science fiction story watching time slowed down? Freaky. A few NOPs and the jump for the loop take up the remaining five cycles for the week.

For the source of the clock he chose to use an LDR to detect when the light level dropped at the end of the day. The problem he immediately ran into was that clouds, bird shadows, and so on, also cause drops in the light level. The solution he found was to widen the light and dark range by adding a TLV3702 push-pull output comparator and some resistors. [Ido] gives a detailed explanation of the circuit in the video after the break.

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Tiny Electric Motor Runs On Power From An LED

March 21, 2017 by Manuel Rodriguez-Achach 31 Comments

If you were not aware, LEDs can also work in reverse: they deliver tiny amounts of current, in the microamp range, when illuminated. If you look on YouTube you can find several videos of solar panels built with arrays of LEDs, but powering an electric motor with a single 3 mm LED is something that we’ve never seen before. [Slider2732] built a small electric motor that happily runs from a green LED in sunlight.

The motor uses four coils of 1,000 ohms each. Using coils with many turns of very fine wire helps to draw less current while keeping an appropriate magnetic field for the motor to run. To keep friction at a minimum, the rotor uses a needle that hangs from a magnet. Four neodymium magnets around the rotor are periodically pushed by the coils, generating rotation. A simple two-transistor circuit takes care of the synchronization and yes, the motor does run on the four microamps provided by the LED, and runs pretty well.

Building motors is definitely an enjoyable activity, these small pulse motors can be built in just a couple of hours. You can use coils with just a few tens of turns which are much more easy to make but of course you will need something more than four microamps! The nice part of making an ultralow current motor like this is that it can run for a very long time on a tiny battery or even a capacitor, we invite you to try building one.

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