Monthly Archives: January 2017

SparkFun supports immigration

via SparkFun Electronics Blog Posts

SparkFun is diametrically and unapologetically against the recent presidential executive orders banning refugees and limiting immigrants from primarily Muslim countries. We believe the US is, and has always been, made stronger by the inclusion of many cultures. Without immigration, SparkFun would not exist. We are opposed to President Trump’s anti-Muslim sentiments and orders to enforce barriers between us and our neighboring nations, and will continue to do our part to speak out and protect the livelihoods of all the great people that make up this company and our country.

Best regards,

Glenn and Nate

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Hacker House Smartphone-Connected Door Lock

via Raspberry Pi

The team at YouTube channel Hacker House always deliver when it comes to clear, detailed tutorials, and their newest project, ‘How to Make a Smartphone-Connected Door Lock’, is no exception.

HackerHouse Raspberry Pi Door Lock

Using a Raspberry Pi-powered deadbolt actuator, multiple users can remotely unlock a door via a smartphone app.

The build can be attached to your existing lock, so there’s no need to start pulling out the inner workings of your door.

Hacker House Raspberry Pi Door Lock

The app will also notify you when the door has been unlocked, offering added peace of mind when you’re away from home.

For a full run-through, check out their video below.

How to Make a Smartphone Connected Door Lock

In this video, we show you how to make a smartphone-controlled, internet-connected deadbolt actuator powered by a Raspberry Pi that can be added onto your existing door lock without any modifications to the door. The door lock can be controlled by multiple smartphones, and even notify you whenever someone locks/unlocks the door.

You’ll need access to a 3D printer for some of the parts and, as a way to support their growing channel, the team provide printed parts for sale on eBay.

You may also wish to check out their other Raspberry Pi projects too. They’ve made a lot of cool things, including a Facebook Chatbot, a Portable Arcade Console, a Smart Mirror, and a Motion-tracking Nerf Turret.

How to Make a Raspberry Pi Motion Tracking Airsoft / Nerf Turret

In this video we show you how to build a DIY motion tracking airsoft (or nerf gun) turret with a raspberry pi 3. The airsoft turret is autonomous so it moves and fires the gun when it detects motion. There is also an interactive mode so that you can control it manually from your keyboard.

And in celebration of hitting 50k subscribers, the team are giving away two Raspberry Pis! Just subscribe to their channel and tell them how you would use one in your own project to be in with a chance of winning.

If you have built your own Raspberry Pi-powered lock or security system, we’d love to see it. So go ahead and share it in the comments below, or post it across social media, remembering to tag us in the process.

The post Hacker House Smartphone-Connected Door Lock appeared first on Raspberry Pi.

App note: Designing reliable drones using proper circuit protection

via Dangerous Prototypes


Littelfuse’s application note on drone circuitry protection, offering guard against overcharging its batteries, I/O and ESD protection. Link here (PDF)

No doubt “pilot losing control” is behind many drone incidents and crashes. But what’s behind that “loss of control?” After all, even small recreational drones depend on a host of subsystems – GPS, receiver antennae, WiFi I/O ports and electronic speed controllers – to stay in the air. Lose one and that UAV becomes a UFO pretty quickly.

The number of consumer, professional, and commercial drones, sometimes called unmanned aircraft systems (UASs) or unmanned aerial vehicles (UAVs), sold annually has risen rapidly over the last few years. Future sales growth looks even more rapid, with the Federal Aviation Administration predicting that sales will grow from roughly 2.5 million this year to 7 million by 2020, with 4.3 million being sold to hobbyists and 2.7 million units being sold for professional and commercial applications. Non-military drones are available at a wide range of price points, anywhere from toys that cost less than $100 to sophisticated commercial drones for use in fields like aerial photography, public safety services, agriculture, and wildlife management that can cost thousands

Regardless of how a particular drone is used or how much it costs, all drones are susceptible to similar fault and failure conditions. These conditions can cause problems that range from the merely annoying (a drone that won’t start or take flight) to the catastrophic (a crash that causes major property damage or personal injury). A battery that catches fire during charging or a mid-flight failure due to any of a number of electrical issues are common examples that highlight why robust electrical protection is essential. Fortunately, a growing array of tools and techniques are available to implement passive battery safety systems, electrostatic discharge (ESD) protection, and stalled motor protection.

Free PCB Sunday: Pick your PCB

via Dangerous Prototypes


We go through a lot of prototype PCBs, and end up with lots of extras that we’ll never use. Every Sunday we give away a few PCBs from one of our past or future projects, or a related prototype. Our PCBs are made through Seeed Studio’s Fusion board service. This week two random commenters will get a coupon code for the free PCB drawer tomorrow morning. Pick your own PCB. You get unlimited free PCBs now – finish one and we’ll send you another! Don’t forget there’s free PCBs three times every week:

Some stuff:

  • Yes, we’ll mail it anywhere in the world!
  • Be sure to use a real e-mail in the address field so we can contact you with the coupon.
  • Limit one PCB per address per month please.
  • Like everything else on this site, PCBs are offered without warranty.
  • PCBs are scrap and have no value, due to limited supply it is not possible to replace a board lost in the post

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8-bit Frogger game on a digital microfluidics device

via Arduino Blog

OpenDrop V2 is an updated design for an open-source digital microfludics platform, which was initiated by GaudiLabs in Luzern, Switzerland and developed by several communities including hackteria | open source biological art, BioFlux, and The device is part of a much larger ecosystem focused around digital biology with hopes of making personal lab automation accessible to more people.

OpenDrop runs on a new technology called “electrowetting” to control small droplets of liquids, which allows anyone to carry out digital biology experiments. Potential applications are not only limited to science, but the art, music, games, and education fields as well. One such example is OpenDropper, an 8-bit video game based on the OpenDrop. You can see it below!

Interested in learning more? Read all about the open-source microfluidics platform here.


App note: Magnetic sensors’ and reed switches’ capacitive Loads

via Dangerous Prototypes

An application note from Littelfuse on peak current considerations when reed switches and magnetic sensors are handling capacitive loads. Link here (PDF)

When there is significant capacitance in a reed sensor, reed relay or reed switch circuit, the peak current and energy switched by the reed contacts should be considered. However, if the capacitance is less than 100 nF at 5 V or 0.1 nF at 150 V, and the cable length is less than 10 meters, the capacitance will not significantly effect switching life.

If a capacitor is placed in parallel across the reed contacts, the peak current will be determined by the load voltage, the contact resistance, the wiring resistance, the ESR of the capacitor, and the inductance of the circuitry. Because the resistance and inductance in the circuit path are likely small, the peak current can be amperes or tens of amperes, exceeding the maximum switching current of the reed switch, reed relay or reed sensor. Even if the maximum switching current is not exceeded, switching life may be reduced.

A capacitor not directly across the reed contacts may still generate a high current spike when the reed contact is closed. Depending on the circuit arrangement, the peak discharge current may occur when the capacitor is charged or discharged. Components other than capacitors can have significant capacitance, including long cables, MOVs (Metal Oxide Varistors), and MOSFET gates.