All posts by Alex Bate

Three-factor authentication is the new two-factor authentication

Post Syndicated from Alex Bate original https://www.raspberrypi.org/blog/three-factor-authentication-raspberry-pi/

Two-factor authentication continues to provide our online selves with more security for our email and online banking. Meanwhile, in the physical world, protecting our valuables is now all about three-factor authentication.

A GIF of a thumbprint being scanned for authentication - three-factor authentication

Not sure what I mean? Here’s a video from Switched On Network that demonstrates how to use a Raspberry Pi to build a three-factor door lock comprised of an RFID keyring, 6-digit passcode, and one-time access code sent to your mobile phone.

Note that this is a fairly long video, so feel free to skip it for now and read my rather snazzy tl;dr. You can come back to the video later, with a cup of tea and 20 minutes to spare. It’ll be worth it, I promise.

Build a Raspberry Pi Smart Door Lock Security System with Three Factor Authentication!

https://amzn.to/2A98EaZ (UK) / https://amzn.to/2LDlxyc (US) – Get a free audiobook with a 30-day trial of Audible from Amazon! Build the ultimate door lock system, effectively turning your office or bedroom into a high-security vault!

The tl;dr of three-factor door locks by Alex Bate

To build Switched On Network’s three-factor door lock, you need to source a Raspberry Pi 3, a USB RFID reader and fob, a touchscreen, a electronic door strike, and a relay switch. You also need a few other extras, such as a power supply and a glue gun.

A screenshot from the three-factor authentication video of a glue gun

Once you’ve installed the appropriate drivers (if necessary) for your screen, and rotated the display by 90 degrees, you can skip ahead a few steps by installing the Python script from Switched On Network’s GitHub repo! Cheers!

A screenshot from the three-factor authentication video of the screen attached to the Pi in portrait mode

Then for the physical build: you need to attach the door strike, leads, and whatnot to the Pi — and all that together to the door and door frame. Again, I won’t go into the details, since that’s where the video excels.

A screenshot from the video of the components of the three-factor authentication door lock

The end result is a superior door lock that requires you to remember both your keys and your phone in order to open it. And while we’d never suggest using this tech to secure your house from the outside, it’s a perfect setup for inside doors to offices or basement lairs.

A GIF of Dexter from Dexter's Laboratory

Everyone should have a lair.

Now go watch the video!

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I feel the earth move under my feet (in Michigan)

Post Syndicated from Alex Bate original https://www.raspberrypi.org/blog/michigan-seismic-activity-raspberry-pi/

The University of Michigan is home to the largest stadium in the USA (the second-largest in the world!). So what better place to test for spectator-induced seismic activity than The Big House?

The Big House stadium in Michigan

The Michigan Shake

University of Michigan geology professor Ben van der Pluijm decided to make waves by measuring the seismic activity produced during games at the university’s 107601 person-capacity stadium. Because earthquakes are (thankfully) very rare in the Midwest, and therefore very rarely experienced by van der Pluijm’s introductory geology class, he hoped this approach would make the movement of the Earth more accessible to his students.

“The bottom line was, I wanted something to show people that the Earth just shakes from all kinds of interactions,” explained van der Pluijm in his interview with The Michigan Daily. “All kinds of activity makes the Earth shake.”

The Big House stadium in Michigan

To measure the seismic activity, van der Pluijm used a Raspberry Pi, placing it on a flat concrete surface within the stadium.

Van der Pluijm installed a small machine called a Raspberry Pi computer in the stadium. He said his only requirements were that it needed to be able to plug into the internet and set up on a concrete floor. “Then it sits there and does its thing,” he said. “In fact, it probably does its thing right now.”

He then sent freshman student Sahil Tolia to some games to record the moments of spectator movement and celebration, so that these could be compared with the seismic activity that the Pi registers.

We’re not sure whether Professor van der Pluijm plans on releasing his findings to the outside world, or whether he’ll keep them a close secret with his introductory students, but we hope for the former!

Build your own Raspberry Pi seismic activity reader

We’re not sure what other technology van der Pluijm uses in conjunction with the Raspberry Pi, but it’s fairly easy to create your own seismic activity reader using our board. You can purchase the Raspberry Shake, an add-on board for the Pi that has vertical and horizontal geophones, MEMs accelerometers, and omnidirectional differential pressure transducers. Or you can fashion something at home, for example by taking hints from this project by Carlo Cristini, which uses household items to register movement.

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Raspberry Pi would like you to remember…

Post Syndicated from Alex Bate original https://www.raspberrypi.org/blog/fireworks-2018/

…remember, the 5th of November. Happy Guy Fawkes Night, Bonfire Night, Fireworks Night…Day!

A brief history of the Gunpowder Plot

In 1605, York-born Guy Fawkes was arrested, along with other conspirators of the Gunpowder Plot, for their attempt to blow up the House of Lords that, at the time, was occupied by members of parliament, including King James I.

To celebrate their king surviving the attempt on his life, residents of London lit bonfires, and this became a recognised custom across England on every 5 November to follow. 413 years on, we continue the tradition by burning effigies of Guy Fawkes on bonfires, setting off fireworks, and eating over-priced hotdogs while getting a little tipsy on mulled cider at council-organised events.

Guy Fawkes, in case you’re wondering, was sentenced to death and, after breaking his neck while climbing the gallows, was quartered, and his body parts were distributed to the four corners of the kingdom — another tradition at the time. Good thing we haven’t kept that one going!

Bonfire Night and Raspberry Pi

“Okay, Alex, we get it. You like Bonfire Night. But what has this got to do with Raspberry Pi?”

I’m glad you asked.

While I do enjoy Bonfire Night, I’m not a massive fan of too many fireworks. Or rather, I’m not a fan of the way too many fireworks upset my cat Jimmy.

So when I saw this cute digital fireworks display by Mike ‘Recantha’ Horne, I cheered with delight. He says:

This is a nice little project that I wrote the code for a couple of Sundays ago. It uses the Pimoroni Mote to appear as fireworks and then uses Pygame to play the sound of fireworks as each Mote stick ‘explodes’ in a shower of sparkles! You can see the effect in the video below and see the code here. You can get hold of your own Mote from Pimoroni. This is all in aid of the Milton Keynes Raspberry Jam on 10 November, which is a “Fireworks Special”!

Mike’s project is a great example of using tech to overcome an everyday issue — in this case, letting me have pretty flashing lights in the dark that don’t scare my cat but still make me go “Oooh!” and “Aaah!”.

Fireworks on the Raspberry Pi with the Pimoroni Mote

Uploaded by Michael Horne on 2018-10-28.

If you’ve created any similar indoor versions of usually outdoor activities using a Raspberry Pi, now is the time to share them with us, either in the comments below or on social media.

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Dance magic, dance

Post Syndicated from Alex Bate original https://www.raspberrypi.org/blog/dance-magic-dance/

 Firstly, I’d like to apologise for rickrolling you all yesterday. I would LIKE to, but I can’t — it was just too funny to witness.

But as I’m now somewhat more alive and mobile, here’s a proper blog post about proper things. And today’s proper thing is these awesome Raspberry Pi–powered dance costumes from students at a German secondary school:

In the final two years at German gymnasiums (the highest one of our secondary school types), every student has to do a (graded) practical group project. Our school is known for its superb dancing groups, which are formed of one third of the students (voluntarily!), so our computer science teacher suggested to make animated costumes for our big dancing project at the end of the school year. Around 15 students chose this project, firstly because the title sounded cool and secondly because of the nice teacher 😉.

Let me just say how lovely it is that students decided to take part in a task because of how nice the teacher is. If you’re a nice teacher, congratulations!

The students initially tried using Arduinos and LED strips for their costumes. After some failed attempts, they instead opted for a Raspberry Pi Zero WH and side-emitting fibre connected to single RGB LEDs — and the result is rather marvellous.

To power the LEDs, we then had to shift the voltage up from the 3.3V logic level to 12V. For this, we constructed a board to hold all the needed components. At its heart, there are three ULN2803A to provide enough transistors at the smallest possible space still allowing hand-soldering.

Using pulse-width modulation (PWM), the students were able to control the colour of their lights freely. The rest of the code was written during after-school meetups; an excerpt can be found here, along with a complete write-up of the project.

I’m now going to hand this blog post over to our copy editor, Janina, who is going to write up a translated version of the above in German. Janina, over to you…

[Ed. note: Nein, danke.]

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Trick or (the ultimate) treat!

Post Syndicated from Alex Bate original https://www.raspberrypi.org/blog/trick-or-treat/

I’ll keep today’s blog post short and sweet, because Liz, Helen, and I are all still under the weather.

Raspberry Pi 4!

Don’t tell Eben, Liz, or the rest of the team I showed you this, but here’s your Halloween ‘trick or treat’ gift: an exclusive sneak peek at the Raspberry Pi 4.

We’ll be back to our regularly scheduled programming from tomorrow.

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Build your own robotic cat: Petoi returns

Post Syndicated from Alex Bate original https://www.raspberrypi.org/blog/robotic-cat-petoi-nybble/

Who wouldn’t want a robot kitten? Exactly — we knew you’d understand! And so does the Petoi team, hence their new crowdfunding campaign for Petoi Nybble.

Petoi Nybble

Main campaign video. Back our Indiegogo campaign to adopt Nybble the robo kitten! Share with your friends who may love it! Indiegogo: https://igg.me/at/nybble A more technical post: https://www.hackster.io/RzLi/petoi-nybble-944867 Don’t forget to follow Twitter @PetoiCamp and subscribe to Petoi.com for our newsletters! Most importantly, enjoy our new kitten!

Petoi mark 2

Earlier this year, we shared the robotic cat project Petoi by Rongzhong Li. You all loved it as much as we did, and eagerly requested more information on making one.

Petoi Raspberry Pi Robot Cat

Rongzhong’s goal always was for Petoi to be open-source, so that it can be a teaching aid as much as it is a pet. And with his team’s crowdfunding campaign, he has made building your own robot cat even easier.

Petoi the laser-cut robotic cat

Laser kitty

In the new Nybble version of Petoi, the team replaced 3D-printed parts with laser-cut wood, and cut down the parts list to be more manageable: a Raspberry Pi 3B+, a Sparkfun Arduino Pro Mini, and the Nybble kit, available in the Nybble IndieGoGo campaign.

Petoi the laser-cut robotic cat

The Nybble kit! “The wooden frame is a retro design in honor of its popstick-framed ancestor. I also borrowed the wisdom from traditional Chinese woodwork (in honor of my ancestors), to make the major frame screw-free.”

But Nybble is more than just wooden parts and servo motors! The robotic cat’s artificial intelligence lets users teach it as well as control it,  so every kitty will be unique.

Nybble’s motion is driven by an Arduino-compatible micro-controller. It stores instinctive “muscle memory” to move around. An optional AI chip, such as a Raspberry Pi, can be mounted on top of Nybble’s back, to help Nybble with perception and decision. You can program in your favorite language, and direct Nybble to walk around simply by sending short commands, such as “walk” or “turn left”!

The NyBoard

For this version, the Petoi team has created he NyBoard, an all-in-one controller board for the Raspberry Pi. It’s available to back for $45 if you don’t want to pledge $200 for the entire cat kit.

Petoi the laser-cut robotic cat

Learn more

If you’d like to learn more about Nybble, visit its IndieGoGo campaign page, find more technical details on its Hackster.io project page, or check out the OpenCat GitHub repo.

Petoi the laser-cut robotic cat

And if you’ve built your own robotic pet, such as a K-9–inspired dog, or Raspberry Pi–connected android sheep, let us know!

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Rescuing old cine film with Raspberry Pi Zero

Post Syndicated from Alex Bate original https://www.raspberrypi.org/blog/rescuing-old-cine-film-raspberry-pi-zero/

When Electrical Engineer Alan Platt was given the task of converting old cine film to digital footage for his father-in-law’s 70th birthday, his first instinct was to look online.

converting cine film to digital footage with a Raspberry Pi Zero

“There are plenty of companies happy to convert old films”, he explains, “but they are all extremely expensive. In addition, you have to send your original films away by post, and there’s no way to guarantee that they’ll be safe in transit.”

Alan was given a box of Super 8 films covering 15 years of family holidays and memories. A huge responsibility, and an enormous challenge. Not content to let someone else do the hard work, Alan decided to convert the films himself — and learn how to program a Raspberry Pi at the same time.

converting cine film to digital footage with a Raspberry Pi Zero

Alan’s cine film digitising machine

The best-laid plans

Alan’s initial plan involved using his father-in-law’s cine projector as the base for the conversion process, but this soon proved impossible. There was no space in the projector to house both the film-playing mechanism, and the camera for the digitisation process. Further attempts to use the projector came to an end when, on powering it up for the first time, the 50-year-old machine produced a loud bang and a large cloud of smoke.

Undeterred, Alan examined the bust projector’s mechanism and decided to build his own. This began with a large eBay order: 3-D printed components from Germany, custom-shaped PTFE sheets from the UK, and optical lenses from China. For the skeleton of the machine, Alan’s box of Technic LEGO was dusted off and unpacked; an old TV was dug out of storage to interface with the Raspberry Pi Zero.

converting cine film to digital footage with a Raspberry Pi Zero

Experimentation: Technic LEGO, clamps, and Blu Tack hold the equipment together

The build commenced with several weeks of trial and error using scraps of cine film, a Camera Module, and a motor. With the Raspberry Pi Zero, Alan controlled the motion of the film through the machine, and took photos of each frame.

“At one point, setting the tension on the film required a helper to stand next to me, holding a sledgehammer connected to the pick-up reel. Moving the sledgehammer up or down varied the tension, and allowed me to work out what power of motor I would need to make the film run smoothly.”

He refined the hardware and software until the machine could produce reliable, focused, and stable images.

A slow process

Over a period of two months, the finished machine was used to convert all the cine films. The process involves loading a reel onto a Technic LEGO arm, feeding the film through the mechanism with tweezers, and winding the first section on to the pick-up reel. The Raspberry Pi controls a stepper motor and the Camera Module, advancing the film frame by frame and taking individual photos of each film cell. The film is backlit through a sheet of translucent PTFE serving as a diffuser; the Camera Module is focused by moving it up and down on its aluminium mounting.

converting cine film to digital footage with a Raspberry Pi Zero

Alan taught himself to program in Python while working on this project

Finally, Alan used Avidemux, a free video-editing program, to stitch all the images together into an MP4 digital film.

The verdict

“I’m incredibly proud of this machine”, Alan says. “It has taken more than a quarter of a million photos, digitised hundreds of meters of film — and taught me to program in Python. It demonstrates you don’t need to be an expert software engineer to make something really cool!”

And Alan’s father-in-law?

“He was thrilled! Being able to watch the films on his TV without having to set up the projector was fantastic. It was a great present!”

Here, exclusively for the Raspberry Pi blog, we present the first moments of footage to be digitised using Alan’s machine.

converting cine film to digital footage with a Raspberry Pi Zero

Gripping footage, filmed at Windsor Safari Park in 1983

Digital footage

Have you used a Raspberry Pi to digitise family memories? Do you have a box of Super 8 films in the attic, waiting for a machine like Alan’s?

Tell us about it in the comments!

Thanks again, Rachel

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Beer Cooler or: a Raspberry Pi Zero W walks into a bar…

Post Syndicated from Alex Bate original https://www.raspberrypi.org/blog/raspberry-pi-beer-cooler/

You know how it is. You move into a house that used to be a pub, and you can’t bring yourself to do away with the bar. In fact, after several years of planning, you find yourself buying a hand pump on eBay, and a polypin of craft ale from the local microbrewery. Suddenly, you’re the landlord. The barkeep. Everyone’s best friend.

A GIF from the movie Shaun of the Dead - Raspberry Pi Beer Cooler

And yet …

There’s something not quite right about this setup. Something not quite perfect. You’re pulling pints and drinking your craft ale one day when you realise — the beer isn’t cold enough!

You need a beer cooler.

Cool customer

Electrical engineer Alan Platt found himself in this enviable position, and he decided to design his own draft ale fridge.

‘The original pub cellar had been filled in, so I couldn’t keep my beer underground and pipe it up to the handpump — it had to sit under the bar. I needed to build my own beer cooler, because there is only so much space under the bar, and a commercial fridge wouldn’t fit.”

Alan set about constructing a box for the beer using sheets of insulation board and elastic bands. He then installed two Peltier cooling pumps in the lid of the box, and routed a pipe up to the handpump for the beer. One trip to the microbrewery later, and the craft ale was chilling nicely.

The outside of Alan's beer cooler showing the cooling apparatus and insulation boards

Alan’s beer cooler

But there was a problem.

‘The Peltiers ran happily for an hour or two, but after that, they proved to be too effective. A layer of ice built up on the heat sink connected to the cold side of the Peltiers, jamming the fans, and allowing the beer to grow warm. They also made a horrible rattling sound, and disturbed everyone in the house.”

It seemed that the perfect pint was still out of reach.

Complex circuitry

Not to be defeated, Alan realised he would need a way to control the power to the Peltier units. Switching the power using a simple thermostat would cause damaging thermal shock in the Peltiers, so Alan turned to Raspberry Pi Zero W as his solution.

A photo of the inside of Alan’s beer cooler complete with Raspberry Pi and a heap of wiring (as described in the paragraph below)

Testing the completed control circuit

In order to fine-tune the cooling process, Alan decided to control the current running through the Peltier units. He used a hardware PWM output on a Raspberry Pi Zero W alongside a power MOSFET, an inductor, a capacitor, and a current measurement circuit to create a switched-mode variable current power supply. By measuring the temperature on the cold side of the Peltier units, and using a PID control loop to adjust the PWM output, Alan was able to maintain the cold side at just above freezing. He used a second PID control loop to keep the beer inside the fridge at a perfect cellar temperature of 8°C.

Aware that this cooling system was both overcomplicated and built from very high-power components, Alan designed multiple failsafes using hardware and software to ensure that the control unit would not spontaneously combust while attempting to cool the beer.

The perfect pint was within reach.

Consultation

And then Alan tried to explain the failure modes to his wife, in case he wasn’t in the house when the electronics overheated, or the failsafes kicked in.

“I wanted her to know what to do if the cooler failed”, Alan explains. “But this required her to check the beer fridge regularly. It’s on the floor, under the bar, and she didn’t seem keen.”

The project was about to get significantly more complicated.

What about an audible alarm?

It was an innocent suggestion, but the idea grew from a simple beeping alarm to a series of spoken alerts. What could be used to produce these alerts?

“I found myself programming a second Raspberry Pi Zero with a DAC HAT, audio amp, and speaker, just to communicate the status of the beer cooler. Originally, the spoken alert was to indicate a fault in the control circuits, but it seemed a waste to stop at a single message.”

A breadboard covered in wires - Raspberry Pi Beer Cooler

Prototype for the audio amplifier

After days of planning, programming, and searching for MP3 files online, the fridge can now inform Alan (and his wife) when it is switched on, when the Peltiers power up, when it reaches maximum power, when it is switched off, and when there is a fault.

The alert messages are all quotes from sci-fi shows and films: Han Solo claiming he has a bad feeling about this; Scotty telling Captain Kirk that the Enterprise is giving it all she’s got; and Kaylee telling Captain Reynolds that everything is shiny.

And the fault alert?

“If there’s a problem with the beer cooler, the Raspberry Pi declares ‘Danger, Will Robinson, danger.’ on a loop, until someone checks it and resets the controls. It’s annoying and effective!”

The perfect pint

The Raspberry Pi also acts as a web server, using the REMI library to display and change the temperatures, currents, and control parameters, so the beer temperature can be monitored and regulated from anywhere on the home WiFi network.

The final build next to a laptop displaying the beer cooler web interface for maintenance on the go

Control box and web interface

Alan’s beer cooler has been successfully tested, and several polypins of local craft ale have been drunk and enjoyed — and it’s only taken two Raspberry Pis; some high-current circuitry; two Peltier units; a pile of household insulation board; and Han Solo, Scotty, Kaylee, and the robot from Lost In Space to achieve the perfect pint.

Over-engineering

Use the comments to tell us about your own over-engineered projects and any excuses you’ve found for including an extra Raspberry Pi in your build!

And thank you to Rachel, aka ‘the wife’, for this wonderful blog post!

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Electronics 101.1: Electricity basics

Post Syndicated from Alex Bate original https://www.raspberrypi.org/blog/electronics-101-1-electricity-basics/

In HackSpace issue 9, Dave Astels helps us get familiar with what electricity is, with some key terms and rules, and with a few basic components. Get your copy of HackSpace magazine in stores now, or download it as a free PDF here.

An animated GIF of Pickachu the Pokemon

tl;dr There’s more to electricity than Pikachu.

Electricity basics

Electricity is fascinating. Most of our technology relies on it: computers, lights, appliances, and even cars, as more and more are hybrid or electric. It follows some well-defined rules, which is what makes it so very useful.

According to Wikipedia, electricity is ‘the set of physical phenomena associated with the presence and motion of electric charge’. And what’s electric charge? That’s the shortage or excess of electrons.

Let’s go back (or forward, depending on where you are in life) to high school science and the atom. An atom is, at a very simplified level, a nucleus surrounded by a number of electrons. The nucleus is (again, viewing it simply) made up of neutrons and protons. Neutrons have no charge, but protons have a positive charge. Electrons have a negative charge. The negative charge on a single electron is the exact opposite of the positive charge on a single proton. The simplest atom, hydrogen, is made from a single proton and a single electron. The net charge of the atom is zero: the positive charge of the proton and the negative charge of the electron cancel – or balance – each other. An atom’s electrons aren’t just in an amorphous cloud around the nucleus: you can think of them as being arranged in layers around the nucleus…rather like an onion. Or perhaps an ogre. This is a very simplified visualisation of it, but it suffices for our purposes.

A diagram of a copper atom and the text '29 Electrons'

Figure 1: A very stylised representation of a copper atom with its electron shell

In a more complex atom, say copper, there are more protons, neutrons, and electrons, and the electrons are in more layers. By default, a copper atom has 29 protons and 35 neutrons in its nucleus, which is surrounded by 29 electrons. The way the electrons are distributed in their layers leaves the copper atom with a single electron in the outermost layer. This is represented in Figure 1 (above). Without getting further into subatomic physics, let’s just say that having that single electron in the outermost layer makes it easier to manipulate. When we put a bunch of copper atoms together to make copper metal (e.g. a wire), it’s easy to move those outermost electrons around inside the metal. Those electrons moving around is electricity. The amount of electrons moving over a period of time is called ‘current’.

A multimeter showing the figure 9.99 with a resistor connected via crocodile clips

A single 10 kΩ resistor reads almost 10 000 ohms (no electrical component is perfect).

We started by talking about electrons and charge. Look back at the Wikipedia definition: ‘presence and motion of electric charge’. Charge is measured in coulombs: 1 coulomb is approximately 6.242 × 1018 electrons. That’s 6 242 000 000 000 000 000 electrons. They’re very small. Actually, this would be -1 coulomb. +1 coulomb would be that many protons (or really, the net lack of that many electrons).

That’s charge. Now let’s consider moving charge, which is far more useful in general (unless your goal is to stick balloons to the wall). Consider some amount of charge moving through a wire. The amount of charge that moves past a specific point (and thus through the wire) over a period of time is called ‘current’ (just like the current in a river) and is measured in amperes, generally just called amps. Specifically, 1 amp is equal to 1 coulomb flowing past a point in 1 second.

Another common term is voltage. You can think of voltage like water pressure; it’s the pressure pushing the electrons (i.e. charge) through a material. The higher the voltage (measured in volts), the faster charge is pushed through, i.e. the higher the current.

The final term is resistance, measured in ohms. Resistance is just what it sounds like. It’s a measure of how much a material resists the movement of electrons. We said that copper allows electrons to move freely. That’s what makes it so common for wires, PCB traces, etc. We say that it is a good conductor. Glass, on the other hand, locks its electrons in place, not letting them move. It’s an example of a good insulator. There are materials that are in between: they let electrons move, but not too freely. These are crucial to making electronics work.

There’s an interesting (and useful) relationship between voltage, current, and resistance called Ohm’s Law (Georg Ohm was the fellow who explored and documented this relationship): the current (denoted I, in amps) flowing through a material is equal to the voltage across the material (denoted V, in volts) divided by the material’s resistance (denoted R, in ohms): I = V/R. This equation is foundational and, as such, very handy.

Lighting up

There aren’t many electronic devices that don’t have at least one LED on them somewhere, especially not gadgety ones. If you look at a simple Arduino Uno, it has LEDs for power, Tx, Rx, and pin 13. The first program using electronic components that most people try is one to blink an LED.

A colour spectrum from red to purple

Figure 2: The colour spectrum

LED stands for light-emitting diode. We’ll come back to diodes in a later instalment; all we need to know right now is that a diode has to go the right way around. So that leaves ‘light-emitting’. That simply means that it gives off light: it lights up. Specifically, it lights up when enough current flows through it. Be careful, though. Put too much current through it and it’ll likely crack in two. Seriously, we’ve done it. Best case scenario, you’ll get a bright pulse of light as it burns out. How much current do they like? 20 milliamps (20mA) is typical. Because an LED is a diode, i.e. a semiconductor (we’ll look at these in more detail in a future instalment too), it defies Ohm’s Law. How? It always has the same voltage across it, regardless of the current flowing through it.

An LED will have a specific Vf (f is for forward, as in ‘forward voltage’), which will be defined in its data sheet.

The voltage varies with the colour of light that the LED emits, but usually between 1.8V and 3.3V. Vf for red LEDs will typically be 1.8V, and for blue LEDs 3V–3.3V. As a rule, LEDs with a higher frequency colour will have a larger Vf. Figure 2 (above) shows the colour spectrum. Colours on the right end are lower in frequency and LEDs emitting those colours will have a lower Vf, while those on the left end have a higher frequency and a higher Vf.

A screenshot of resistor-calculator website

Resistor colour bands show the resistance. Online calculators can help you learn the values.

So an LED will have a fixed Vf, and a typical LED that we’ll use likes about 20mA of current. An LED won’t do anything to limit how much current is flowing through it. That’s what we meant when we said it defies Ohm’s Law.

If we take a blue LED and hooked it to a 3.3V power supply, it will shine happily. Do the same thing with a red LED, and it will blink and burn out. So how do we deal with that? How do we use 3.3V or 5V to make an LED light up without burning out? We simply limit the current flowing through it. And for that, we need a resistor and Ohm’s Law.

Getting protection

Figure 3: An LED with a current-limiting resistor

If we want to power a red LED from a 5V source, we know the following information: current has to be 20mA, Vcc will be 5V, and the voltage across the LED will be 1.8V. Consider the circuit in Figure 3. The voltage across the resistor will be Vcc – Vf, i.e. 5 – 1.8 = 3.2V. We said the current through the LED should be 20mA. Since there is only one path through the circuit that goes through the resistor as well as the LED, all current has to flow through both: whatever amount of current flows through the resistor has to flow through the LED, no more, no less. This is the crucial thing to realise. We can calculate the value of the resistance needed using Ohm’s Law: R = V/I = 3.2V/20mA = 3.2V/0.020A = 160 ohms.

The resistor should have a value of 160 ohms to allow 20mA of current to flow through the LED. Knowing that the 20mA and 1.8V values are approximate and that resistors are not exact (+/- 5 or 10 percent are the most common), we chose a slightly higher-value resistor. Considering common resistor values, go with 180 ohm or 220ohm. A higher-value resistor will allow slightly less current through, which might result in a slightly dimmer light. Try it and see. For practical purposes, simply using a 220 ohm resistor usually works fine.

Parallel lines

In the previous section we connected a resistor and an LED end to end. That’s called a series circuit. If we connected them side by side, it would be a parallel circuit. Consider the circuits in Figure 4.

Figure 4: A – series circuit; B – parallel circuit

We’ll use 5V for Vcc. What is the total resistance between Vcc and GND in each circuit? How much current is flowing through each circuit? What is the voltage across each resistor?

When resistors are connected in series, as in circuit A, the resistances are added. So the two 100 ohm resistors in series have a total resistance of 200 ohms.

When resistors are connected in parallel, as in circuit B, it’s more complex. Each resistor provides a path for current to flow through. So we could use an indirect method to calculate the total resistance. Each resistor is 100 ohms, and has one end connected to 5V and the other to 0V (GND), so the voltage across each one is 5V. The current flowing through each one is 5V/100 ohms = 0.05A, or 50mA. That flows through each resistor, so the total current is 100mA, or 0.1A. The total resistance is then R = V/I = 5V/0.1A = 50 ohms. A more direct way is to use the equation 1/Rt = 1/R1 + 1/R2 + … + 1/Rn, where Rt is the total resistance, and R1, R2, etc. are the values of the individual resistors that are in parallel. Using this, 1/Rt = 1/100 + 1/100 = 2/100 = 1/50. So Rt = 50. This is a quicker way to do it, and only involves the resistor values.

An image of a multimeter

A multimeter can read voltage, ampage, and resistance

Now for current. We know that the series circuit has a total resistance of 200 ohms, so the current will be I = V/R = 5V/200 ohm = 0.025A = 25mA. For one 100 ohm resistor the current is 5V/100 ohm = 0.05A = 50mA. This is expected: if the resistance is lower, there is less ‘resistance’ to current flowing, so with the same voltage, more current will flow. We already computed the current for the parallel circuit: 100mA. This is higher because we know that each resistor has 50mA flowing through it. In a parallel circuit, the currents are added.

A multimeter showing the figure 19.88 with a resistor connected via crocodile clips

Two 10kΩ (kiloohm) resistors in series read (almost) 20kΩ

The final question is what voltage is across each resistor. Let’s look at the parallel circuit first. One end of each resistor is connected to 5V, and the other end of each is connected to 0V (GND). So clearly, the voltage across each one is 5V. In a series circuit it’s different. We can use Ohm’s Law because we’ve calculated the current flowing through each one (0.025A), and that current flows through both resistors. Each resistor is 100 ohm, so the voltage across each one will be V = I×R = 0.025A × 100 ohm = 2.5 V. This makes sense intuitively, since the resistors have the same value and the same current is flowing through both. It makes sense that the voltage across each would be equal, and half of the total. Remember that it’s unlikely to be exactly half, due to the slop in the resistor values.

Let’s do this one more time with unequal resistors. See Figure 5.

Figure 5: A – series circuit; B – parallel circuit

For the series circuit, we simply add the resistances: 100ohm + 82ohm = 182ohm. The current is 5V / 182ohm = 0.0274725A = 27.4725 mA. Because resistors are inexact, it’s safe to call this 27.5mA. The voltages are 100ohm × 0.0275A = 2.75V across the 100 ohm resistor, and 82ohm × 0.275 = 2.25V across the 82 ohm one. The voltages always have to add up, accepting rounding errors. Relative to ground, the voltage at the point between the resistors is 2.75V. What will happen if we make the top resistor smaller (i.e. have a lower resistance)? The total resistance goes down, the current goes up, so the voltage across the 100ohm resistor goes up. This is what’s generally called a voltage divider.

For the parallel circuit we can use 1/Rt = 1/100 + 1/82 = 82/8200 + 100/8200 = 182/8200 = 1/45, so Rt = 45ohm. The total current is 5V / 45ohm = 0.111A = 111mA. For the individual resistors, the currents are 5V / 100ohm = 50mA and 5V / 82ohm = 61mA. Add these up and we have the total current of 111mA. Parallel resistors act as a current divider.

A multimeter showing the figure 4.96 with a resistor connected via crocodile clips

Two 10kΩ resistors in parallel read (almost) 5kΩ.

I encourage you to create these little circuits on a breadboard and measure the resistances, voltages, and currents for yourself.

Resistors in series for a voltage divider, resisters in parallel for a current divider

Consider what happens if we replace the resistor connected to Vcc in a series circuit with a variable resistor. The voltage between the resistors will vary as the value of the resistor does. As the resistance goes down, the voltage goes up. The reverse is true as well: as the resistance goes up, the voltage goes down. One use of this is to replace the variable resistor with a photoresistor. A photoresistor’s value depends on how much light is shining on it (i.e. how many photons are hitting it, to be precise). More light = lower resistance. Now the voltage divider can be used to measure the strength of light. All you need to do is connect the point between the resistors to an analogue input and read it.

Figure 6 Combined parallel and series circuits

We’ve had a brief look at the basic concepts of electricity: charge, current, voltage, and resistance. We’ve also had a closer look at resistors and ways of combining them. We finished with a practical example of a series resistor circuit being used to measure light.

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Halloween voice-changer using Raspberry Pi Zero

Post Syndicated from Alex Bate original https://www.raspberrypi.org/blog/halloween-voice-changer-using-raspberry-pi-zero/

Olivier Ros has put together a short and sweet tutorial for creating your own voice-changing mask for Halloween.

Voice changer with Raspberry Pi Zero for Halloween

How to make a voice changer with Raspberry Pi Zero for Halloween Buy MIC+ sound card on Amazon : goo.gl/VDFzu7 tutorial here: https://www.instructables.com/id/Halloween-Voice-Changer-With-Raspberry-Pi/ https://www.raspiaudio.com/halloween

Halloween — we love it!

Grab your ghostly fairy lights, hollow out your pumpkins, and hunt down your box of spooky knick-knacks — it’s Halloween season! And with every year that passes, we see more and more uses of the Raspberry Pi in haunting costumes and decorations.

Voice-changers

At the top of the list is an increase in the number of voice changers. And Olivier Ros’s recent project is a great example of an easy-to-build piece costumimg that’s possible thanks to the small footprint of the Raspberry Pi Zero.

An image of the Raspberry Pi Zero voice changer inside a scary mask

Playdough: so many uses, yet all we wanted to do as kids was eat it.

Oliver used a Pi Zero, though if you have the mask fit it into, you could use any 40-pin Pi and an audio DAC HAT such as this one. He also used Playdough to isolate the Zero and keep it in place, but some foam should do the trick too. Just see what you have lying around.

When I said this is an easy project, I meant it: Olivier has provided the complete code for you to install on a newly setup SD card, or to download via the terminal on your existing Raspbian configuration.

You can read through the entire build on his website, and see more of his projects over on his Instructables page.

More Halloween inspiration

If you’re looking to beef up your Halloween game this October, you should really include a Raspberry Pi in the mix. For example, our Halloween Pumpkin Light tutorial allows you to control the light show inside your carved fruit without the risk of fire. Yes, you read that correctly: a pumpkin is a fruit.

Halloween Pumpkin Light Effect

Use a Raspberry Pi and Pimoroni Blinkt! to create an realistic lighting effect for your Halloween Pumpkin.

For more inspiration and instructions, check out John Park’s Haunted Portrait, some of our favourite tweeted spooky projects from last year, and our list of some of the best Halloween projects online.

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SelfieBot: taking and printing photos with a smile

Post Syndicated from Alex Bate original https://www.raspberrypi.org/blog/selfiebot-sophy-wong-raspberry-pi-camera/

Does your camera giggle and smile as it takes your photo? Does your camera spit out your image from a thermal printer? No? Well, Sophy Wong’s SelfieBot does!

Raspberry Pi SelfieBot: Selfie Camera with a Personality

SelfieBot is a project Kim and I originally made for our booth at Seattle Mini Maker Faire 2017. Now, you can build your own! A full tutorial for SelfieBot is up on the Adafruit Learning System at https://learn.adafruit.com/raspberry-pi-selfie-bot/ This was our first Raspberry Pi project, and is an experiment in DIY AI.

Pasties, projects, and plans

Last year, I built a Raspberry Pi photobooth for a friend’s wedding, complete with a thermal printer for instant printouts, and a Twitter feed to keep those unable to attend the event in the loop. I called the project PastyCam, because I built it into the paper mache body of a Cornish pasty, and I planned on creating a tutorial blog post for the build. But I obviously haven’t. And I think it’s time, a year later, to admit defeat.

A photo of the Cornish Pasty photo booth Alex created for a wedding in Cornwall - SelfieBot Raspberry Pi Camera

The wedding was in Cornwall, so the Cornish pasty totally makes sense, alright?

But lucky for us, Sophy Wong has gifted us all with SelfieBot.

Sophy Wong

If you subscribe to HackSpace magazine, you’ll recognise Sophy from issue 4, where she adorned the cover, complete with glowing fingernails. And if you’re like me, you instantly wanted to be her as soon as you saw that image.

SelfieBot Raspberry Pi Camera

Makers should also know Sophy from her impressive contributions to the maker community, including her tutorials for Adafruit, her YouTube channel, and most recently her work with Mythbusters Jr.

sophy wong on Twitter

Filming for #MythbustersJr is wrapped, and I’m heading home to Seattle. What an incredible summer filled with amazing people. I’m so inspired by every single person, crew and cast, on this show, and I’ll miss you all until our paths cross again someday 😊

SelfieBot at MakerFaire

I saw SelfieBot in passing at Maker Faire Bay Area earlier this year. Yet somehow I managed to not introduce myself to Sophy and have a play with her Pi-powered creation. So a few weeks back at World Maker Faire New York, I accosted Sophy as soon as I could, and we bonded by swapping business cards and Pimoroni pins.

Creating SelfieBot

SelfieBot is more than just a printing photo booth. It giggles, it talks, it reacts to movement. It’s the robot version of that friend of yours who’s always taking photos. Always. All the time, Amy. It’s all the time! *ahem*

SelfieBot Raspberry Pi Camera

SelfieBot consists of a Raspberry Pi 2, a Pi Camera Module, a 5″ screen, an accelerometer, a mini thermal printer, and more, including 3D-printed and laser-cut parts.

sophy wong on Twitter

Getting SelfieBot ready for Maker Faire Bay Area next weekend! Super excited to be talking on Sunday with @kpimmel – come see us and meet SelfieBot!

If you want to build your own SelfieBot — and obviously you do — then you can find a complete breakdown of the build process, including info on all parts you’ll need, files for 3D printing, and so, so many wonderfully informative photographs, on the Adafruit Learning System!

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Google Tasks to-do list, or anti-baby-distraction device

Post Syndicated from Alex Bate original https://www.raspberrypi.org/blog/interactive-raspberry-pi-google-tasks/

Organise your life with the help of a Raspberry Pi, a 3.5″ touchscreen, Google Tasks, and hackster.io user Michal Sporna.

Distracting baby optional, though advised.

Google Tasks Raspberry Pi to-do list Michael Sporna

Baby – in the workplace – thought you ought to know

There’s a baby in the office today. And, as babies tend to do in places of work, he’s stolen all of our attention away from what we’re meant to be doing (our jobs), and has redirected it for the greater good (keeping him entertained). Oh, baby!

If only I had a to-do list to keep all my day’s tasks in plain sight and constantly remind myself of what I should be doing (writing this blog post) instead of what I’m actually doing (naming all the kittens on my T-shirt with the help of a nine-month-old)!

Hold on…

Sorry, the baby just came over to my desk and stole my attention again. Where was I?

Oh yes…

…to-do lists!

Michal Sporna‘s interactive to-do list that syncs with Google Tasks consists of a Raspberry Pi 3 Model B and a 3.5″ touchscreen encased in a laser-cut wooden housing, though this last element is optional.

Google Tasks Raspberry Pi to-do list Michael Sporna

“This is yet another web to-do app, but designed for a 3.5″ screen and Raspberry Pi,” says Michal in the introduction to his hackster.io tutorial. “The idea is for this device to serve as task tracking device, replacing a regular notebook and having to write stuff with pen.”

Michal explains that, while he enjoys writing down tasks on paper, editing items on paper isn’t that user-friendly. By replacing pen and paper with stylus and touchscreen, and making use Google Tasks, he improved the process for himself.

Google Tasks

The Google Tasks platform allows you to record and edit tasks, and to share them across multiple devices. The app integrates nicely with Gmail and Google Calendar, and its browser functionality allowed Michal to auto-run it on Chromium in Raspbian, so his tasks automatically display on the touchscreen. #NotSponsored

Google Tasks Raspberry Pi to-do list Michael Sporna

Build your own

Find full build details for the to-do list device on hackster.io! This is the first project Michal has shared on the website, and we’re looking forward to more makes from him in the future.

Now, where did that baby go?

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A waterproof Raspberry Pi?! Five 3D-printable projects to try

Post Syndicated from Alex Bate original https://www.raspberrypi.org/blog/waterproof-3d-printing-raspberry-pi/

Summer is coming to a close. The evenings grow darker. So pack away your flip flops, hang up your beach towel, and settle in for the colder months with these fun 3D-printable projects to make at home or in your local makerspace.

Fallout 4 desktop terminal

Power Up Props’ replica of the Fallout desktop terminals fits a 3.5″ screen and a Raspberry Pi 3B. Any Fallout fans out there will be pleased to know that you don’t need to raise your Science level to hack into this terminal — you’ll just need access to a 3D printer and these free files from My Mini Factory.

Fallout 4 terminal 3d-printable raspberry pi case

And while you’re waiting for this to print, check out Power Up Props’ wall-mounted terminal!

Fallout 4 – Working Terminal (Raspberry Pi Version) – Power Up Props

Howdy neighbors, grab some fusion cores and put on your power armor because today we’re making a working replica of the wall mounted computer “terminals” from the Fallout series, powered by a Raspberry Pi! Want one of your very own terminals?

Falcon Heavy night light

Remixing DAKINGINDANORF‘s low-poly Arduino-based design, this 3D-printable night light is a replica of the SpaceX Falcon Heavy rocket. The replica uses a Raspberry Pi Zero and a Pimoroni Unicorn pHAT to create a rather lovely rocket launch effect. Perfect for the budding space explorer in your home!

Falcon Heavy night light

I 3D printed a SpaceX Falcon Heavy night light, with some nice effects like it’s actually launching. Useful? Hell no. Cool? Hell yes! Blogpost with files and code: https://www.dennisjanssen.be/tutorials/falcon-heavy-night-light/

You can download the files directly from Dennis Janssen’s website.

Swimming IoT satellite

We’re really excited about this design and already thinking about how we’ll use it for our own projects:

Floating Raspberry Pi case

Using an acrylic Christmas bauble and 3D-printed parts, you can set your Raspberry Pi Zero W free in local bodies of water — ideal for nature watching and citizen science experiments.

Art Deco clock and weather display

Channel your inner Jay Gatsby with this Art Deco-effect clock and weather display.

Art Deco Raspberry Pi Clock

Fitted with a Raspberry Pi Zero W and an Adafruit piTFT display, this build is ideally suited for any late-night cocktail parties you may have planned.

High-altitude rocket holder

Send four Raspberry Pi Zeros and Camera Modules into the skies with this holder design from Thingiverse user randysteck.

Raspberry Pi Zero rocket holder

The 3D-printable holder will keep your boards safe and sound while they simultaneously record photos or video of their airborne adventure.

More more more

What projects did we miss? Share your favourite 3D-printable designs for Raspberry Pis in the comments so we can see more builds from the internet’s very best community!

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Working model of the Trinity Buoy Wharf Lighthouse

Post Syndicated from Alex Bate original https://www.raspberrypi.org/blog/raspberry-pi-model-trinity-buoy-wharf-lighthouse/

When Dave shared his Raspberry Pi Zero–powered model of the Trinity Buoy Wharf Lighthouse on Reddit, we fell a little bit in love.

Lame_Dave's Raspberry Pi Trinity Buoy Wharf Lighthouse

Hello from the Trinity Buoy Wharf Lighthouse

Dave was getting married inside London’s only lighthouse, situated at Trinity Buoy Wharf across the water from the O2 Arena.

Lame_Dave's Raspberry Pi Trinity Buoy Wharf Lighthouse

The Trinity Buoy Wharf Lighthouse

The Trinity Buoy Wharf lighthouse sits at the confluence of the River Thames (the big ol’ river running through London) and Bow Creek, a tidal estuary of the River Lea (the river Adele sings about in her song River Lea*!). When the wharf was closed in 1988, the lighthouse was put out of commission.

Dave is wonderful, and so are his lighthouses

On Reddit, Dave goes by the username Lame_Dave, but considering how wonderful and thoughtful his project for his lighthouse wedding is, we hereby rename him Wonderful_Thoughtful_Dave. Don’t put yourself down, Dave. You’re brilliant!

“I knew I wanted to make something involving electronics and 3D printing,” explains Wonderful_Thoughtful_Dave in an imgur post. “So I decided to make working model lighthouses as the table centrepieces.”

Designing and building ten tabletop lighthouses

Dave designed the 3D model in Autodesk 123D, with a plethora of photographs of the lighthouse as reference points. And many hours later, he began 3D printing ten lighthouse shells using his Prusa MK2.5.



With Samsung 18650 batteries and a 18650 shield for power, Dave hooked up Raspberry Pi Zeros to 6×2 LCD displays, LEDs, and stepper motors. With these components, each lighthouse to gives off a rather lovely light while also showing table number and meal status to guests. Neat!

Lame_Dave's Raspberry Pi Trinity Buoy Wharf Lighthouse

“Each lighthouse has a JSON file on the Pi that tells it what messages to display when, so each table is personalised.”

The final result is beautiful and would look at home anywhere from a model town to a toy shop, or indeed the entrance of the Trinity Buoy Wharf Lighthouse itself.

We love how Dave put different maker skills to use here, from 3D design and printing, to constructing and coding. Hopefully, we’ll see more projects from him in the future!

Remaking classic landmarks

Here in the UK, people have a thing for iconic buildings. And at Pi Towers, we adore it when you recreate historic landmarks like this with the help of our humble board.

Why not try creating your own reimagining, such as the Project Arthur ISS tracker, a papercraft and Pi build that pays homage to Arthur, the first satellite dish at the Cornish Goonhilly Earth Satellite Station?

Arthur satellite dish Trinity Buoy Wharf Lighthouse

Or come up with something completely new! We’d love to see, say, a working model of London’s Tower Bridge, or a light-up King’s College Chapel. Whatever landmark makes your day, why not build a scale model using your maker skills and electronics?

 

 

 

*Sadly, we are unable to share the song for copyright issues, so here is the Adele edition of Carpool Karaoke instead.

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Today’s blog post is about Junie Genius

Post Syndicated from Alex Bate original https://www.raspberrypi.org/blog/junie-genius/

It’s Monday. It’s morning. It’s England. The members of the Raspberry Pi Comms team begin to filter into Pi Towers, drowsy and semi-conscious. We’re tired from our weekends of debauchery.

One by one, we file into the kitchen. Fingers are clutching the handles of favourite mugs as we line up for the coffee machine. Select, click, wait. Select, click, wait. Double Americanos and Flat Whites pour, steaming hot and promising the glorious punch of caffeine to finally start our week.

Back in the office space, we turn on laptops, sign into Slack, and half-heartedly skim through pending messages while the coffee buzz begins to make its way through our systems, bringing us back to life.

“Ooooh”, comes a voice from the end desk, and heads turn towards Alex, who has opened the subscriptions page of the Raspberry Pi YouTube channel.

“Ooooh?” replies Helen, lifting herself from her chair to peer over the dividing wall between their desks.

“New Junie!”

Figures gather behind the Social Media Editor as she connects her laptop to her second display and enlarges the video to fullscreen.

It’s Monday. It’s morning. It’s England. And mornings like this are made for Junie Genius.

ROBOTS RUINED MY LIFE (and my sleep schedule)

This week, it gets personal. In the past, I’ve fought robots, and robots have fought me, BUT NOW, together, we’re fighting crime. SUPPORT ME ON PATREON: https://www.patreon.com/JunieGenius HANG W/ ME ONLINE: INSTAGRAM – https://www.instagram.com/juniegenius/ TWITTER – https://twitter.com/Junie_Genius I HAVE TEE SHIRTS: https://teespring.com/stores/junie-genius?page=1 #23942939_ON_TRENDING If you see this, comment if you would join my team of robotic Avengers.

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Your face, 14 ft tall: image mapping with As We Are

Post Syndicated from Alex Bate original https://www.raspberrypi.org/blog/as-we-are-face-mapping/

While at World Maker Faire New York last weekend, I found myself chatting to a rather lovely gentleman by the name of Mac Pierce. During our conversation, Mac mentioned a project he’d worked on called As We Are, an interactive art installation located in the Greater Columbus Convention Center in Columbus, Ohio.

as we are

“So it’s this 14-foot head covered in LEDs…”, Mac began, and after his brief explanation, I found myself grabbing nearby makers to have him tell them about the project too. I was hooked! I hadn’t even seen photos of the sculpture, yet I was hooked. And true to his word, Mac had the press release for As We Are sitting in my inbox when I returned to Pi Towers.

So here is it:

The Greater Columbus Convention Center: “As We Are” – Creating the Ultimate Selfie Machine

DCL, an award-winning fabricator of architectural specialties and custom experiential design elements, worked with artist Matthew Mohr to develop, engineer and fabricate this 14ft, 7,000lb, interactive digital sculpture. Featuring custom LED modules, an integrated 3D photobooth, 32 cameras, and a touch-screen display – this unique project combines technologies to present a seamless experience for visitors to display their own portrait on the sculpture.

As We Are

The brainchild of artist Matthew Mohr, As We Are was engineered and produced by DCL, an award-winning Boston-based fabricator whose greatest achievement to date, in my opinion at least, is hiring Mac Pierce.

as we are

YAY!

DCL built the 14-foot structure using 24 layers of aluminium ‘ribs’ covered in custom Sansi LED modules. These modules add up to an astounding 850000 individual LEDs, allowing for crisp detail of images displayed by the build.

as we are

When a visitor to the Convention Center steps inside the interactive sculpture, they’re met with a wall of 32 Raspberry Pis plus Camera Modules. The Pis use facial recognition software to 3D scan the visitor’s face and flattened the image, and then map the face across the outer surface of the structure.

Matthew Mohr was inspired to show off the diversity of Columbus, OH, while also creating a sense of oneness with As We Are. Combining technology and interaction, the sculpture has been called “the ultimate selfie machine”.

If you’re in or near Columbus and able to visit the installation, we’d love to see your photos, so please share them with us on our social media platforms.

Raspberry Pi facial mapping as we are

You see now why I was dumbstruck when Mac told me about this project, yes?

Always tell us

Had it not been for a chance encounter with Mac at Maker Faire, we may never have heard of As We Are. While Matthew Mohr and DCL installed the sculpture in 2017, very little fuss was made about the use of Raspberry Pis within it, and it completely slipped under our radar. So if you are working on a project for your business, as a maker, or for any other reason, and you’re using a Raspberry Pi, please make sure to let us know by emailing [email protected].

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Networked knitting machine: not your average knit one, purl one

Post Syndicated from Alex Bate original https://www.raspberrypi.org/blog/knitting-network-printer/

The moment we saw Sarah Spencer‘s knitted Stargazing tapestry, we knew we needed to know more. A couple of emails later, and here’s Sarah with a guest blog post telling you all you need to know about her hacking adventure with a 1980s knitting machine and a Raspberry Pi.

Knitting Printer! (slowest speed)

Printing a scarf on a Brother KM950i knitting machine from the 1980’s. To do this I have a Brother Motor arm to push the carriage back and forth and a homemade colour changer that automatically selects the colour on the left (the white and purple device with the LED).

Here’s Sarah…

Raspberry Pi: what’s there not to like? It’s powerful, compact, and oh so affordable! I used one as a portable media box attached to a pico projector for years. Setting one up as a media box is one of the most popular uses for them, but there’s so much more you can do.

Cue a 1980s Brother domestic knitting machine. Yep, you read that right. A knitting machine – to knit jumpers, hats, scarves, you name it. They don’t make domestic knitting machines any more, so a machine from the 1980s is about as modern as you can get. It comes with an onboard scanner to scan knitting patterns and a floppy drive port to back up your scans to an old floppy disk. Aah, the eighties – what a time to be alive!

Building a networked knitting machine

But this is an article about Raspberry Pi, right? So what does a 30-year-old knitting machine have to do with that? Well, I hacked my domestic knitting machine and turned it into a network printer with the help of a Raspberry Pi. By using a floppy drive emulator written in Python and a web interface, I can send an image to the Raspberry Pi over the network, preview it in a knitting grid, and tell it to send the knitting pattern to the knitting machine via the floppy drive port.

Sarah Spencer Networked knitting machine

OctoKnit

I call this set-up OctoKnit in honour of a more famous and widely used tool, OctoPrint for 3D printers, another popular application for Raspberry Pi.

Sarah Spencer Knitting Network Printer

I’ve made the OctoKnit web interface open source. You can find it on GitHub.

This project has been in the works for several years, and there’s been a few modifications to the knitting machine over that time. With the addition of a motor arm and an automatic colour changer, my knitting is getting very close to being hands-free. Here’s a photo of the knitting machine today, although the Raspberry Pi is hiding behind the machine in this shot:

Sarah Spencer Networked knitting machine

I’ve specialised in knitting multicolour work using a double-layered technique called double Jacquard, which requires two beds of needles. Hence the reason the machine has doubled in size from when I first started.

Knitting for Etsy

I made a thing that can make things, so I need to make something with it, right? Here are a few custom orders I’ve completed through my Etsy store:

Sarah Spencer Networked knitting machine

Stargazing

However, none of my previous works quite compares to my latest piece, Stargazing: a knitted tapestry. Knitted in seven panels stitched together by hand, the pattern on the Raspberry Pi is 21 times bigger than the memory available on the vintage knitting machine, so it’s knitted in 21 separate but seamless file transfers. It took over 100 hours of work and weighs 15kg.

Sarah Spencer Networked knitting machine

Stargazing is a celestial map of the night sky, featuring all 88 constellations across both Northern and Southern hemispheres. The line through the center is the Earth’s equator, projected out into space, with the sun, moon and planets of our solar system featured along it. The grey cloud is a representation of our galaxy, the Milky Way.

Heart of Pluto on Twitter

Happy 6pm, Fri 31st Aug 2018 😊 The tapestry is installed and the planets in the sky have now aligned with those in the knitting

When I first picked up a Raspberry Pi and turned it over in my hand, marvelling at the computing power in such a small, affordable unit, I never imagined in my wildest dreams what I’d end up doing with it.

What will you do with your Raspberry Pi?

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Watching VinylVideo with a Raspberry Pi A+

Post Syndicated from Alex Bate original https://www.raspberrypi.org/blog/vinylvideo-with-raspberry-pi/

Play back video and sound on your television using your turntable and the VinylVideo converter, as demonstrated by YouTuber TechMoan.

VinylVideo – Playing video from a 45rpm record

With a VinylVideo convertor you can play video from a vinyl record played on a standard record player. Curiosity, tech-demo or art?

A brief history of VinylVideo

When demand for vinyl dipped in the early nineties, Austrian artist Gebhard Sengmüller introduced the world to his latest creation: VinylVideo. With VinylVideo you can play audio and visuals from an LP vinyl record using a standard turntable and a converter box plugged into a television set.

Gebhard Sengmüller original VinylVideo

While the project saw some interest throughout the nineties and early noughties, in the end only 20 conversion sets were ever produced.

However, when fellow YouTuber Randy Riddle (great name) got in touch with UK-based tech enthusiast TechMoan to tell him about a VinylVideo revival device becoming available, TechMoan had no choice but to invest.

Where the Pi comes in

After getting the VinylVideo converter box to work with an old Sony CRT unit, TechMoan decided to take apart the box to better understand how it works

You’ll notice a familiar logo at the top right there. Yes, it’s using a Raspberry Pi, a model A+ to be precise, to do the video decoding and output. It makes sense in a low-volume operation — use something that’s ready-made rather than getting a custom-made board done that you probably have to buy in batches of a thousand from China.

There’s very little else inside the sturdy steel casing, but what TechMoan’s investigation shows is that the Pi is connected to a custom-made phono preamp via USB and runs software written specifically for the VinylVideo conversion and playback.

Using Raspberry Pi for VinylVideo playback

For more information on the original project, visit the extremely dated VinylVideo website. And for more on the new product, you can visit the revival converter’s website.

Be sure to subscribe to TechMoan’s YouTube channel for more videos, and see how you can support him on Patreon.

And a huge thank you to David Ferguson for the heads-up! You can watch David talk about his own Raspberry Pi project, PiBakery, on our YouTube channel.

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How to mod your Etch A Sketch, or Toy Story in real life

Post Syndicated from Alex Bate original https://www.raspberrypi.org/blog/mod-etch-a-sketch-toy-story/

We’d like to file this under ‘things we wish we’d had when we were younger’. Who else is envious of the kids of today and all the cool things they can make with our old classic toys?

Etch A Sketch Robot – Elephant

Read about how this works on my blog! http://sunnybala.com/2018/09/10/python-etch-a-sketch.html

To a wave of upvotes and comments, Sunny Balasubramanian shared their Etch A Sketch project on Reddit, including all the information and code you need to build your own. Thanks, Sunny!

Dismantling the toys of our childhoods

The physical set up of the automated Etch A Sketch is pretty simple: motors attached to couplers replace the original plastic nobs, and a connected Raspberry Pi 3 controls the motors as directed by the code.

Etch a Sketch modded with a Raspberry Pi

For stability, Sunny attached a wooden block to the plastic housing that keeps the motors in place.

Coding new life into an Etch A Sketch

Sunny explains:

There’s a few different ways to go about this portion of the project. When I started out, I googled to see if anyone had done things like this before. A few projects popped up. They seemed to approach the drawing in one of two ways. I wanted to do it in a fully automated way where the only input is a picture and the output is a cleanly drawn image.

The code Sunny ended up using first takes an image and simplifies it into a line drawing using Canny edge detection. It then turns each pixel to a node and draws a path between the nodes, connecting them one by one. So that the Etch A Sketch draws the picture, the Raspberry Pi then directs the motors to follow the connections and create uncannily precise sketches.

Raspberry Pi Etch-a-sketch
Raspberry Pi Etch-a-sketch

Head to Sunny’s website for more information about their project, and download the full code from GitHub.

Two down, more to go…

With this automated Etch A Sketch, and this talking Fisher Price Chatter Telephone, the Raspberry Pi community is well on the way to recreating the entire Toy Story cast, and we are fully on board with that!

A GIF of Toy Story characters

So what’s next? A remote-controlled Slinky? A falling with style flying Buzz Lightyear? What would you build?

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You wouldn’t download a car…

Post Syndicated from Alex Bate original https://www.raspberrypi.org/blog/you-wouldnt-download-car-telsa-hack/

You wouldn’t download a car…but is that just because none of us know how to? And OF COURSE none of us know how to: it’s a really hard thing to do!

Raspberry Pi Tesla

Dramatic reenactment using a Mini because, c’mon, as if I can afford a Tesla!

Nikola Tesla was in love with a pigeon 😍🐦

True story. He was also the true father of the electrical age (sorry, not sorry, Edison) and looked so much like David Bowie that here’s David Bowie playing Nikola Tesla:

David Bowie as Nicola Tesla — Raspberry Pi Tesla

Not even pigeon love

Which is the perfect segue, as here’s a Tesla playing David Bowie, and here’s also where our story truly begins…

Some people dislike Tesla (the car manufacturer, not the scientist) but we love them

But some people also dislike going to the dentist, so ¯\_(ツ)_/¯. (I also love going to the dentist.)

I’m pretty sure the reason some people have issues with Tesla is that electric cars still seem like a form of magic we’re not quite comfortable with.

Whatever people’s reason for holding a grudge against Tesla, recent findings at a university in Belgium this week have left the tech community aflutter: the academics announced that, with the aid of a “$35 computer”, they can clone your Tesla car key and steal. Your. Car.

If you haven’t guessed yet, we’re the ones behind the $35 computer. (Hi!)

Says WIRED: A team of researchers at the KU Leuven University in Belgium on Monday plan to present a paper at the Cryptographic Hardware and Embedded Systems conference in Amsterdam, revealing a technique for defeating the encryption used in the wireless key fobs of Tesla’s Model S luxury sedans. With about $600 in radio and computing equipment, they can wirelessly read signals from a nearby Tesla owner’s fob. Less than two seconds of computation yields the fob’s cryptographic key, allowing them to steal the associated car without a trace.

When I said that the tech community was all aflutter, what I meant was, on the whole, we find this hack somewhat entertaining but aren’t all that shocked by it. Not because we hate Tesla, but because these things happen. Technology is ever evolving, and that $600 worth of kit can do a thing to another thing isn’t all that unbelievable.

Sweet Cyber Jones on Twitter

The keys to my new Tesla https://t.co/jNViEZBxrB

The academics showed an example of the hack using “just” a couple of radios, a Raspberry Pi, some batteries, and your basic, off-the-shelf “pre-computed table of keys on a portable hard drive”. And through the magic of electric car IoT technology, Tesla instantly released a series of fixes to allow existing Tesla users to protect their cars against the attack, which is all kinds of cool.

Alex, why are you making such light of this?!

Because The Fast and the Furious isn’t real. And I highly doubt there’s a criminal enterprise out there that’s capable of building the same technology as well-funded university researchers.

Yes, this study from KU Leuven University is interesting. And yes, we all had a good laugh at the expense of Tesla and Elon Musk, but we don’t need academics to provide material for that. And I genuinely love Tesla and the work Elon is doing. True love.

Instead, we should be seeing this as a reminder that data encryption and online security are things we all need to take seriously in this digital world. So stop connecting your phone to whatever free WiFi network you can find, stop using PASSWORD123 for all your online accounts, and spend a little more time learning how you can better protect yourself and your family from nasty people on the internet.

And leave Britney Tesla alone!

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