Category Archives: Aggregated

Free PCB coupon via Facebook to 2 random commenters

via Dangerous Prototypes


Every Friday we give away some extra PCBs via Facebook. This post was announced on Facebook, and on Monday we’ll send coupon codes to two random commenters. The coupon code usually go to Facebook ‘Other’ Messages Folder . More PCBs via Twitter on Tuesday and the blog every Sunday. Don’t forget there’s free PCBs three times every week:

Some stuff:

  • Yes, we’ll mail it anywhere in the world!
  • We’ll contact you via Facebook with a coupon code for the PCB drawer.
  • Limit one PCB per address per month, please.
  • Like everything else on this site, PCBs are offered without warranty.

We try to stagger free PCB posts so every time zone has a chance to participate, but the best way to see it first is to subscribe to the RSS feed, follow us on Twitter, or like us on Facebook.

New Product Friday: By the Dawn’s Early Photon

via SparkFun Electronics Blog Posts

Tomorrow is Independence Day for everyone here at SparkFun, like everyone else in the United States. Luckily we made sure we had some new products available before we leave. We are pleased to announce that the shield add-ons for the Photon module are now available for purchase! Needless to say, we are very excited to be able to start shipping these out to get them into your hands. Let’s go ahead and take another look at the awesomeness of the Photon ecosystem!

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Preorders have officially ended for the Photon shields. The Photon add-on shields are officially live, and we couldn’t be happier! In the Photon line you will find a simple Weather Shield equipped with a variety of sensors, a versatile motion-sensing IMU Shield similar to our 9DOF boards, a Micro OLED Shield that utilizes the same display found in the MicroView, a Battery Shield designed to power your module, a Wearable Shield for your e-textiles project, and a simple ProtoShield. Check out our dedicated Particle Photon Category for a closer and more in-depth look at each board.

SparkFun Ardumoto Shield Kit

$ 29.95

Next up, we have the SparkFun Ardumoto Shield Kit. Ththis easy to use kit is perfect for any interested robot enthusiasts and includes an Ardumoto Shield as well pairs of tires, motors, connectors, and wires. And, of course, it’s all stuffed in a classic SparkFun red box (which may come in handy as a robot chassis itself). That’s right, no more annoying plastic clamshell!

SparkFun PicoBoard Lab Pack

$ 949.95

This SparkFun PicoBoard Lab Pack includes 10 complete PicoBoard student kits and other assorted features. Each lab pack has everything you need including the PicoBoard, hardware, and extra components. The PicoBoard allows you to create interactions with various sensors. Using the Scratch programming language, you can easily create simple interactive programs based on the input from sensors. The PicoBoard incorporates a light sensor, sound sensor, a button and a slider, as well as 4 additional inputs that can sense electrical resistance via included cables.

Well, folks that’s another New Product Friday wrapped up. If you are celebrating this 4th of July we wish you many happy booms and hope you all stay safe. We’ll see you next week (hopefully with all of our fingers and eyebrows still attached) with plenty of more new products. See you then!

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Climate control

via Raspberry Pi

If you’re in the UK this week, you’ll hear a lot of people muttering darkly about the big yellow ball in the sky, and how they’re having to mist the bed with water in order to get it cool enough to sleep, or steal fans from their children’s bedrooms, or make makeshift beds on the cool tiled floor in the kitchen out of cushions. (All overheard at Pi Towers yesterday.)

And Jon is wearing three-quarter length trousers.


The UK, you see, does’t really do summer. So this week’s egg-cookingly hot heatwave has had us all wishing we had air conditioning – while it’s pretty standard these days in offices, nobody (apart from my mother, who has a mobile unit she calls Mr Freeze because she is awesome like that) really has one at home, unlike those of you in countries whose summers last longer than the standard British week. Mark my words. Next week it’ll be raining again.

The outlay for an air conditioning unit at home is pretty big – they’re unusual, so not very cheap here – but there are options. You can build your own 12v evaporative unit very cheaply, with a PC fan, a bucket, an aquarium pump and some inexpensive electronics and bits and bobs from the homewares shop: this version comes in at about £40. You can take it a step further and add a cheap thermostatic switch.


And, of course, now you’re equipped with an air conditioner that you have made with your own hands, you can start to automate your house. Because that’s what we do here when we’re not spraying the bed sheets and wearing trousers which display our calves.

If you’re taking cooling seriously, you should be looking not just at active cooling like the orange bucket swamp cooler; but also at stopping the heat from building up in the first place. Chris Rieger from Australia has a neat and simple home automation project that controls his blinds as well as his air conditioning. (If you have curtains, you can automate those too – see this project from Jamie Scott, which would be easy to incorporate into Chris’s system in place of the blinds mechanism.)

Chris has made a neat little GUI you can use to control the system over a web interface, with the ability to automate by time or temperature, or to manually turn the system on or off. Full instructions are available at his website.

So really, Great Britain, you’ve got no excuses to keep complaining. I expect to see you all ripping out old PC fans and buying buckets at Homebase this weekend.


The post Climate control appeared first on Raspberry Pi.

Tiny x86 Systems With Graphics Cards

via Hackaday » hardware

The Intel Edison is out, and that means there’s someone out there trying to get a postage-stamp sized x86 machine running all those classic mid-90s games that just won’t work with modern hardware. The Edison isn’t the only tiny single board computer with an x86 processor out there; the legends told of another, and you can connect a graphics card to this one.

This build uses the 86Duino Zero, a single board computer stuffed into an Arduino form factor with a CPU that’s just about as capable as a Pentium II or III, loaded up with 128 MB of RAM, a PCI-e bus, and USB. It’s been a while since we’ve seen the 86Duino. We first saw it way back at the beginning of 2013, and since then, barring this build, nothing else has come up.

The 86Duino Zero only has a PCI-e x1 connector, but with an x16 adapter, this tiny board can drive an old nVidia GT230. A patch to the Coreboot image and a resistor for the Reset signal to the VGA was required, but other than that, it’s not terribly difficult to run old games on something the size of an Arduino and a significantly larger graphics card.

Thanks [Rasz] for sending this one in.

Filed under: hardware

Bus Pirate v3.8 free PCB build

via Dangerous Prototypes


@ursudima tweeted picture of his free Bus Pirate v3.8 PCB build. The Bus Pirate is an open source hacker multi-tool that talks to electronic stuff.

If you build a free PCB we’ll send you another one! Blog about it, post a picture on Flicker, whatever – we’ll send you a coupon code for the free PCB drawer.

Get your own handy Bus Pirate for $30, including world-wide shipping. Also available from our friendly distributors.

Enginursday: Celebratin’ ‘Merica with Fireworks!

via SparkFun Electronics Blog Posts


Local laws vary widely, so before you go making and/or lighting off any fireworks in your area, be sure to check for and adhere to any restrictions, laws, or licensing requirements in your area, and always use extreme caution when handling incendiaries.

Two days from now, most people in the United States will be celebrating Independence Day, and starting back in 1777 people celebrated by setting off fireworks. I considered writing about how to remotely set off fireworks – this allows a safer working distance, and a method to automate a show. If you’d rather learn about that stuff, the Walt Disney Company has interesting patents on the topic, and we have already covered one method in the past.

A sparkler

Common sparkler courtesy of Wikipedia

I have instead decided to write about how to make your own sparklers and the technology behind them. Sparklers are legal in many places, but I cannot speak to the legality of making them yourself. If you decide to DIY, make sure to do it somewere legal. SparkFun doesn’t recommend trying this at home.

While sparklers aren’t the worlds most impressive fireworks, the formulation can be tweaked slightly, or even used as is to make stars for use in ‘real’ fireworks.


Fireworks are made up of oxidizers, fuels, coloring agents, color enhancers, binders, and additives.

To burn rapidly enough or to explode, fireworks must contain their own oxidizer. An oxidizer is a substance that has the ability to oxidize other compounds. Oxidization really only means that the substance looses electrons & increases its oxidation state. The name is due to the fact that oxygen was the first known oxidizing agent, but other chemicals like H2O2, MnO4-, F2, Cl2, & Br2 are all common oxidizers.

The material that burns or oxidizes is the fuel. The reaction between the oxidizer and fuel produces heat and often hot gases such as CO2.

There are two sources of light emission in flame: black body radiation and electron excitation. Black body radiation can only produce red, orange, yellow, and white. Think hot metal such as a range burner. Other colors are obtained through electron excitation. As an atom absorbs thermal energy, orbital electrons are pushed into higher energy orbits. Electrons in the excited states are said to be in higher energy bandgaps. This is an unstable state. The electrons have a tendency to return to a stable orbit, releasing heat or photons in the process. The energy bandgap crossed determines the color of the light emitted. Low energy gaps produce reds, while higher energy gaps produce blues or violets. Coloring agents provide the atoms that release light through electron excitation.

Color enhancers are most commonly chlorine donors. The most common color enhancers are Saran resin, Parlon, and PVC. Stable metal ions burn to form oxides or hydroxides. The chlorine donors form HCl when heated. These oxides and hydroxides combine with the HCl to form metal chlorides. These chlorides enhance volatility and light emission. They provide deeper colors. These chlorinate hydrocarbons also serve as fuels.

Binders are used for exactly what one might guess they are used for – to bind the formulation together. The main binder in this formulation is the dextrin. Dextrin has two roles in this mixture. It is both a binder and a fuel. The dry binder must first be partially dissolved in a solvent before it can bind the formulation. The solvent used varies based on the other chemicals in the mix. Some chemicals will react with the water used in this example.

Sulfur is an ignition promoter. As mixed in it is found as S8. In this form it is safe to store with the oxidizer. When heated it easily breaks down into S2 and S3, which react easily with the KNO3, starting a chain reaction igniting the harder-to-ignite compounds.

Other additives found in fireworks are used to prevent caking. Some are used to buffer or adjust the pH to prevent premature breakdown of compounds. Sometimes metals are covered in a protective coating of wax or oil. None of these additives are used primarily for the reaction, and are mostly stabilizers.


I’m covering a popular formulation that can be found all over and may be attributed to Allen F. Clark, who holds patents in the firework industry from the very beginning of the the 20th century.

Potassium nitrate 64
Barium nitrate 30
Sulfur 16
Airfloat charcoal 16
Antimony sulfide 16
Aluminum   9
Dextrin 16

Formulation, parts by mass. Bind with a 25% ABV solution

Potassium nitrate ( KNO3 ) is an oxidant, or oxidizer. It contains 47.5% oxygen by mass. Pretty obvious to see that with potassium nitrate being the main ingredient and it being nearly ½ oxygen, it’s a main source of oxygen in the reaction.

Barium nitrate ( Ba(NO3)2 ) is also an oxidizer. It contains 36.7% oxygen by mass, and is thus also a major oxidizer in this formulation. Barium compounds produce yellow-green flames, so this sort of acts as a coloring agent too. Unfortunately the BaO formed in decomposition acts as a black body radiator and emits a yellow-white. To get a better green, a chlorine donor is needed to create BaCl, which gives a better green.

Barium is toxic and must be disposed of carefully. It’s best to create insoluble barium sulfate ( BaSO4 ). Mix any leftover barium compounds with Epsom salts in water for a few days to form the barium sulfate.

As stated in the previous section, sulfur is an important ignition promoter, and a fuel.

Airfloat charcoal is a term for very finely ground charcoal. Being finely ground, airfloat charcoal has lots of surface area and reacts fast. It serves as a fuel.

Antimony sulfide ( Sb2S3 ), also known as antimony trisulfide, is another fuel and ignition promoter. Use caution when using this since antimony is fairly toxic. Wearing a face mask or respirator is a good idea in general when working with these powders.

Aluminum is yet another fuel. Due to black body radiation, it burns yellow or white.

Dextrin is the final fuel source, but is mostly included as a binder. It comes in the form of a light yellow powder and must be mixed with water to be effective as a binder. Dextrin is insoluble in alcohol, so make sure you keep your water/alcohol solution below 30%. This formulation calls for 25% alcohol. The exact type of alcohol isn’t important. You can water down Everclear, or even rubbing alcohol. The alcohol helps with wetting and also speeds the drying of the binder.

Dextrin is produced by heating corn starch in the oven at 400˚F. Stir every 15 minutes or so until the corn starch starts to yellow or brown. This should take about 90 minutes.


The list of required supplies is fairly short.

  • Mixing screen
  • Dipping tube
  • Drying rack
  • Bamboo or wooden skewers (or iron wires ~20 gauge)
  • Chemicals listed in the formulation
  • Alcohol (75% ABV)

Prep Work

To properly mix the chemicals, it’s best to use a mixing screen. You could steal a screen off of your neighbor’s house, but for better results you should make your own. At your local hardware store or online, find some brass or stainless steel screen around 200 mesh. You could also use aluminum screen, but the main concern is that the screen you use is non-sparking. You can use 1 by 2’s or 1 by 4’s to make a wooden frame to stretch the screen over. Fix the sides together and affix the screen with non-sparking nails or staples. Brass or copper will work great. The wood will form a tray to contain the powders while you shake the mixture through the screen. You might want to seal the wooden frame with polyurethane if you plan on reusing your screen.

1-1/2″ PVC pipe

1-½″ PVC pipe Courtesy of The Home Depot

A dipping tube can be made from 1.5 inch PVC pipe with an end cap. Make the tube about an inch longer than you plan to make the sticks. Attach the end cap with standard PVC glue and allow to fully cure before using. The day before making the sparklers would work great.

A drying rack can be made from just about anything, including a 2 by 4. Drill a bunch of holes wide enough to fit the skewers or wire, and deep enough to hold them stable. Place the holes far enough apart that you can add wet skewers without disturbing the others; ½″ or so should be fine.


Carefully mix together the chemicals and pour into your screen. Gently work the mixture through the screen into a collection container. Be careful not to grind the chemicals through the screen. The ignition promoters make the compound more sensitive to energy sources such as friction. A brush is a good idea to help work the mixture through the screen.

Slowly stir in your water/alcohol solution. Keep adding more until the mixture becomes syrupy. You will want it thin enough to be pourable, but thick enough that it will leave decent layers during dipping.

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Drying sparklers Courtesy of

Fill the dipping tube to about a ½″ from the top. You will likely need a funnel. One by one, dip the skewers or wire into the dipping tube. Place them into the drying rack for at least an hour or so, and up to a day. If your sparklers look as bad as those in the picture above, then you have not added enough water to the binder. To fix them, roll them on some paper to smooth them out when they are just dry enough not to stick to the paper.

Repeat this process until you build up to the desired thickness. The closer to the final few layers you get, the longer you will want to let the previous layers dry. Wait a full day between the last few layers. When the last layer is added let dry for about four days.

You will likely want to apply a protective coating to the finished product. A nitrocellulose lacquer or more PVC cement will work. This coating will promote smoother burning and prevent the fire from jumping down the sparkler.


As discussed in the section on chemicals, various chemicals produce varying colors. The given formulation relies mostly on black body radiation for color and will be mostly a yellow-white. Try mixing in other metal salts. Try mixing in color enhancers such as potassium perchlorate ( KClO4 ). Before adding other chemicals make sure to do your research. You don’t want to create any self-igniting or toxic compounds. Don’t be this guy!

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