Here’s A Tesla Coil You Can Wear

April 18, 2019 by 3 Comments

It’s badgelife season, and if you need an idea for a killer piece of wearable electronics, look no further than this PCB Tesla coil. Yes, it’s killer, doubly so if you’re wearing a pacemaker.

This project was inspired by an earlier Tesla coil on a PCB project that used 160 turns of 6 mil traces on a circuit board as the secondary. All the electronics are there, and it’s powered by USB. Plug this thing in, and you have a pocket full of lightning that’s approximately 30kV. It probably won’t kill you if you touch it, but let’s not test that too much. [Bobricious] took this idea and ran with it, stripping the circuit down to its bare minimum. Now it’s just a single transistor, with all the other parts printed on a circuit board.

There is one problem with making a Tesla Coil on a PCB, and that’s the number of turns on the coil. Any Tesla coil you’ll find is really just the clever application of a single thin wire wrapped around itself a few hundred or thousands of times. This Tesla coil is no different, and in this case it’s 240 turns of a single trace wrapping around a PCB that is 150mm square. [Bobricius] is one of the kings of putting tiny coils on a PCB, and his fiberglass brushless motor is a testament to that. We also just covered his circular linear motor raceway which also uses PCB coils.

The circuit is simple, just a power jack that accepts something around 20 Volts, a single BD243 transistor, an LED, and an 82k resistor. With that, you can lay a small neon tube on the PCB and watch it light up. With another PCB and another neon tube, this circuit board can transfer wireless power. It’s a fun toy, and it’s all PCB tech.

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Teardown: The Guts Of A Digital Sentry

April 18, 2019 by 6 Comments

I have a home alarm system that has me wondering if I can make it better with my maker Kung-fu. Recently we had to replace our system, so I took the time to dissect the main controller, the remote sensors, and all the bits that make a home security system work.

To be precise, the subject of today’s interrogation is a Zicom brand Home Alarm that was quite famous a decade ago. It connects to a wired telephone line, takes inputs from motion, door, and gas sensors, and will make quite a racket if the system is tripped (which sometimes happened accidentally). Even though no circuits were harmed in the making of this post, I assure you that there are some interesting things that will raise an eyebrow or two. Lets take a look.

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Making A Dash Button Update Your To-do List

April 18, 2019 by 6 Comments

Amazon’s Dash Buttons are useful little devices, that let you automatically order a wide variety of common household goods at the press of a button. They’re cheap and wireless and readily available, and that makes them ripe for hacking. In just this vein, [Inbar] and [Ezra] found a way to make the Dash buttons update their to-do list.

[Inbar] uses Any.do to manage his to-do list. There’s no public API, but the service can be configured to respond to Alexa commands. Naturally, this meant that if a Dash Button could be configured to trigger a voice command, Alexa would then make the necessary additions to the list.

This was achieved with lashings of Python, a Raspberry Pi, and Apple’s text-to-speech engine. The Raspberry Pi is set up as a wireless hotspot, to which the Dash Buttons are connected. When the button is pressed, a DHCP request goes out as the button tries to phone home. By scraping the MAC address from this request, the Raspberry Pi can identify which button has been pressed, and then plays a recorded voice sample of Apple’s Samantha voice. This voice was specifically chosen to be the one most reliably understood by Alexa, which is responsible for parsing the voice command and updating the list on Any.do.

It’s a cheeky hack that doesn’t bother itself with the nitty-gritty of interfacing with various services and tools. Instead, it laces up a bunch of easy-to-use software and hardware, and gets the job done just as well.

As we’ve seen, Amazon’s Dash Button has been thoroughly pwned. Video after the break. Continue reading “Making A Dash Button Update Your To-do List” →

All You Need To Know About I2S

April 18, 2019 by 24 Comments

Last month we marked the 40th birthday of the CD, and it was as much an obituary as a celebration because those polycarbonate discs are fast becoming a rarity. There is one piece of technology from the CD age that is very much still with us though, and it lives on in the standard for sending serial digital audio between chips. The protocol is called I2S and comes as a hardware peripheral on many microcontrollers. It’s a surprisingly simple interface that’s quite easy to work with and thus quite hackable, so it’s worth a bit of further investigation.

It’s A Simple Enough Interface

Don’t confuse this with the other Philips Semiconductor protocol: I2C. Inter-Integrated Circuit protocol has the initials IIC, and the double letter was shortened to come up with the “eye-squared-see” nomenclature we’ve come to love from I2C. Brought to life in 1982, this predated I2S by four years which explains the somewhat strange abbreviation for “Inter-Integrated Circuit Sound”.

The protocol has stuck around because it’s very handy for dealing with the firehose of serial data associated with high-quality digital audio. It’s so handy that you’ve likely heard of it being used for other purposes than audio, which I’ll get to in a little bit. But first, what does I2S actually do?

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Arduboy Goes Thin And Flexible For Portable Gaming

April 18, 2019 by 5 Comments

We all have a gaming system in our pocket or purse and some of us are probably reading on it right now. That pocket space is valuable so we have to budget what we keep in there and adding another gaming system is not in the cards, if it takes up too much space. [Kevin Bates] budgeted the smallest bit of pocket real estate for his full-size Arduboy clone, Arduflexboy. It is thin and conforms to his pocket because the custom PCB uses a flexible substrate and he has done away with the traditional tactile buttons.

Won’t a flexible system be hard to play? Yes. [Kevin] said it himself, and while we don’t disagree, a functional Arduboy on a flexible circuit makes up for practicality by being a neat manufacturing demonstration. This falls under the because-I-can category but the thought that went into it is also evident. All the components mount opposite the screen so it looks clean from the front and the components will not be subject to as much flexing and the inputs are in the same place as a traditional Arduboy.

cost = low, practicality = extremely low, customer service problems = high

     ~[Kevin Bates]

These flexible circuit boards use a polyimide substrate, the same stuff as Kapton tape, and ordering boards is getting cheaper so we can expect to see more of them popping up. Did we mention that we currently have a contest for flexible circuits? We have prizes that will make you sing, just for publishing your flex PCB concept.

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Bone Conducting Headphones Built Into Eye Glasses

April 18, 2019 by 21 Comments

There are times when being seen to listen to music through headphones might get you into trouble. For these moments, reach for a handy solution: bone conduction speakers that discreetly pipe the music to your eardrums through the bone of your skull. [Samuel] wanted just such a covert music listening device, so created his own in a set of 3D-printed glasses.

He first tried using an Adafruit bone-conducting transducer but found that to be too bulky. What you see here is a smaller module that [Samuel] found on AliExpress (search for bone conduction module). The GD-02 is much smaller and thus more suitable for hiding in the arm of a pair of glasses. For the rest of the electronics he used a PCB and battery from a donated set of broken Bluetooth headphones, a space for which he was able to conceal easily in the 3D-printed frame of the glasses. The battery is in one arm and the board in the other, and he says the wiring was extremely fiddly.

The result is a surprisingly svelte set of specs that you might not immediately think concealed some electronics. His choice of bright yellow filament might give the game away, but overall he’s done a great job. This certainly isn’t the first bone conduction project we’ve shown you, some of the others have used motors instead of bone conduction transducers.

Benchtop Lathe Gets An Electronic Leadscrew Makeover

April 17, 2019 by 51 Comments

The king of machine tools is the lathe, and if the king has a heart, it’s probably the leadscrew. That’s the bit that allows threading operations, arguably the most important job a lathe can tackle. It’s a simple concept, really – the leadscrew is mechanically linked through gears to the spindle so that the cutting tool moves along the long axis of the workpiece as it rotates, allowing it to cut threads of the desired pitch.

But what’s simple in concept can be complicated in reality. As [Clough42] points out, most lathes couple the lead screw to the spindle drive through a complex series of gears that need to be swapped in and out to accommodate different thread pitches, and makes going from imperial to metric a whole ball of wax by itself. So he set about building an electronic leadscrew for his lathe. The idea is to forgo the gear train and drive the leadscrew directly with a high-quality stepper motor. That sounds easy enough, but bear in mind that the translation of the tool needs to be perfectly synchronized with the rotation of the spindle to make threading possible. That will be accomplished with an industrial-grade quadrature encoder coupled to the spindle, which will tell software running on a TI LaunchPad how fast to turn the stepper – and in which direction, to control thread handedness. The video below has some great detail on real-time operating systems on microcontrollers as well as tests on all the hardware to be used.

This is only a proof of concept at this point, but we’re looking forward to the rest of this series. In the meantime, [Quinn Dunki]’s excellent series on choosing a lathe should keep you going.

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