Monthly Archives: February 2017

Enhancing Arduino ADC resolution with dithering & oversampling

via Dangerous Prototypes


From the comments on our previous post Improving ADC resolution by oversampling and averaging application note, Edward Mallon writes:

I managed to get oversampling working well on cheap Arduino promini clones. Turns out all you have to do is toggle a digital pin connected to ground with the right size resistor to generate enough noise for the technique to work.

More details at Arduino based underwater sensors homepage.

New distributors in the Americas

via Pololu Blog

Last week, I wrote about our new distributors in Europe. We’ve also added some new distributors in the Americas since our last round of new distributor introductions:

Chicago Electronic Distributors are a new distributor in—you guessed it— Chicago, USA. They offer a variety of Pololu products for sale on their website and free shipping on US orders over $100. They prefer customers buy directly from their website, but they also have an eBay and Amazon store.

FlexRC is an online store in Canada that specializes in multi-rotor drones. They sell a couple of our voltage regulators alone and as part of kits. Search “pololu” on their website to see all their products with Pololu regulators. They have over 50 quadcopter videos on their YouTube channel.

ElectroStore joins our five other distributors in Ecuador. They are based in Quito and Riobamba, but they ship all over the country. Their product selection is available on their Facebook page, and you can contact them to place an order, or you can order through MercadoLibre Ecuador.

Smart Electronics Projects is an online electronics store in Lima, Peru. They sell a variety of Pololu products including motors drivers, encoders, gearmotors, and wheels. They also offer courses in robotic and electronics design, and provide 3D printing, laser cutting, and design services.

CPIDI Vava – Technologies is an online store also in Lima, Peru, bringing the total number of distributors in Peru to three! They carry a selection of Pololu metal gearmotors, wheels, and other products you can see in their Pololu category.

See the full list of over 200 distributors to find one in your area.

The OSHWA Forums: Now Powered by Discourse

via Open Source Hardware Association

We are very pleased to announce that our new community forums are up and running. The discussion forums are powered by Discourse, which is easy to use, easy to maintain, and open source.

Among other new features, Discourse offers the ability to follow and reply to topics via email. This was one of the biggest reasons we decided to migrate our forums from their old home on bbPress. We’re hoping this will breathe some life into what has otherwise been an admittedly dormant part of the site.

All of the topics, replies, and user accounts have been imported from bbPress, but you’ll need to reset your password in order to log in on the new system.

Hope to see you there!

Remotely control a sumo bot with a gaming wheel

via Arduino Blog

Using an Arduino Uno, Nano, and two Bluetooth modules, engineering student “Roboro” can now remotely control his sumo robot.

Like many hackers, Roboro had an old gaming controller that he wasn’t using, in this case an Xbox steering wheel and pedals. Naturally, he converted it into a controller for his sumo robot, which can now be driven manually. This involved wiring the wheel controls into an Uno; the smaller Nano was used onboard the bot.

Rewiring a controller is nothing new, but what is also quite interesting from a hack point of view is that the Arduinos communicate over Bluetooth. When initiated, the controller connects itself to the robot, which can then be driven around (as long as it doesn’t get stuck in the hardwood).

You can see more details of this build on Roboro’s project page.

#FreePCB via Twitter to 2 random RTs

via Dangerous Prototypes


Every Tuesday we give away two coupons for the free PCB drawer via Twitter. This post was announced on Twitter, and in 24 hours we’ll send coupon codes to two random retweeters. Don’t forget there’s free PCBs three times a every week:

  • Hate Twitter and Facebook? Free PCB Sunday is the classic PCB giveaway. Catch it every Sunday, right here on the blog
  • Tweet-a-PCB Tuesday. Follow us and get boards in 144 characters or less
  • Facebook PCB Friday. Free PCBs will be your friend for the weekend

Some stuff:

  • Yes, we’ll mail it anywhere in the world!
  • Check out how we mail PCBs worldwide video.
  • We’ll contact you via Twitter 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.

IoTuesday: 3 Easy DIY Antennas That Increase Your WiFi and Bluetooth Range

via SparkFun Electronics Blog Posts

Many inexpensive IoT development platforms rely on PCB and chip antennas to offer a WiFi or Bluetooth connection in the 2.4GHz Industrial, Scientific and Medical (ISM) band. Chip and PCB antennas offer a cheap, compact solution that fits onto a single board, which is often all that’s needed. They are also a good option if you really do not want a visible antenna on your final design.

ESP8266 Breakout

The ESP8266’s PCB antenna is clearly visible on the edge opposite the headers.

That being said, PCB and chip antennas can be a poor choice for a few reasons:

  • Proximity to other components on the board can affect performance.
  • If you build an enclosure around the board, the enclosure can also adversely affect the antenna’s performance.
  • While not exactly omnidirectional, many chip and PCB antennas are designed to allow for near-equal performance regardless of heading and orientation (with only a few nulls).

If you are attempting to shield your internet-connected environment sensor suite from the elements, you’ll likely want to consider mounting an external antenna onto your project to improve your connection. Some boards, like the ESP8266 Thing Dev, allow you to attach an external antenna to the onboard U.FL connector. Just note that you might have to move some solder around to make it happen.

Buying a good antenna can be expensive, and in the world of do-it-yourself (DIY) electronics, nothing beats making your own antenna out of household items. The three suggestions listed below are most certainly not omnidirectional. They are intended to help boost your range (gain) in a specific direction, which is why they’re known as directional antennas. You can learn a bit about omnidirectional vs. directional antennas here.

Disclaimer: I am not an RF engineer, and I know very little about antenna design and testing. The following homemade antennas were made by people with a lot more knowledge than me, but I can't guarantee they were tested in any official capacity. Make them at your own risk (which is, honestly, the fun part).

The Cantenna

Ian Buckley’s MakeUseOf article covers how to find a good can and turn it into a waveguide.

As it turns out, many store-bought aluminum cans are the perfect shape for a 2.4GHz waveguide (this tool will help you determine the perfect dimensions for your can). From Ian’s post, you’ll want a can that is as close to a 92mm diameter and 147mm length as possible. You then attach a copper wire to an N-type connector to make a probe that’s inserted into the side of the can. Depending on the type of cable and connectors used, you can potentially convert it to a U.FL connector to mate it to your development board.

If properly constructed, you can see a large increase in the range of your wireless connection; just be aware that Cantennas are highly directional, which means you’ll need to point the open end of the can toward your target (e.g., WiFi router). Some people report being able to maintain a connection over several miles with Line of Sight (LoS) in open air.

The Yagi-Uda

Homemeade Yagi antenna

Biotele creates a Yagi-Uda antenna out of paper clips and popsicle sticks on Instructables.

The Yagi-Uda antenna, commonly known as a “Yagi antenna,” was invented by Shintaro Uda and Hidetsugu Yagi in 1926. Prior to cable television, This type of antenna was commonly found affixed to roofs providing high-gain VHF and UHF television reception for many homes. The Yagi-Uda antenna typically consists of a driven element, a reflector, and one or more directors, where the reflector and directors are simply metal rods. The more directors on the antenna, the more directional the beam, which results in higher gain.

Making your own Yagi-Uda can be done very cheaply and requires only a few common tools. Instructables user Biotele shows you how to create your own 2.4GHz Yagi-Uda antenna with paper clips and popsicle sticks. MacGyver would be proud. Biotele claims to get an LoS range of 2 miles with this makeshift antenna.

Tripole with Circular Polarization

Tripole antenna

While more difficult to construct than the previous two, a circularly polarized antenna allows you to communicate with linearly polarized antennas oriented vertically or horizontally (just watch out for nulls). This is useful if you need to, say, talk to your Bluetooth devices in a garden outside your house. user HexHammer.Jez shows you how to build a tripole antenna to extend the range of Bluetooth (or anything in the 2.4GHz band). This antenna has a wider beam width than the Cantenna or Yagi-Uda, but HexHammer.Jez reports an LoS range of about 150 meters using an off-the-shelf USB Bluetooth dongle.

While you can certainly bump the transmit power to get more range (within the FCC limits, of course), using a directional antenna will offer a better connection between your IoT device and base station, assuming you have line of sight and your target is in the main lobe of your antenna (multipath interference can wreak havoc on wireless communications).

What are some other tricks you can think of to maintain a good wireless connection between devices without needing to bump up the transmit power?

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