Android Doorbell Notifier

Breadboarded circuit to detect when doorbell rings

It’s always unfortunate to find a FedEx tag on your door saying you missed a delivery; especially when you were home the whole time. After having this problem a few times [Lee] decided to rig up a doorbell notifier for his Android phone.

[Lee]‘s doorbell uses a 10 VAC supply to ring a chime. To reduce modifications to the doorbell, he added an integrated rectifier and a PNP transistor. The rectifier drives the transistor when the bell rings, and pulls a line to ground.

An old Netgear router running OpenWRT senses this on a GPIO pin. Hotplugd is used to run a script when the button push is detected.

The software is discussed in a separate post. The router runs a simple UDP server written in C. The phone polls this server periodically using SL4A: a Python scripting layer for the Android platform. To put it all together, hotplugd sends a UNIX signal to the UDP server when the doorbell is pushed. Once the phone polls the server a notification will appear, and [Lee] can pick up his package without delay.

Mood lamp/notifier uses neat modular PCB design


Not only does this mood lamp which [J. Sutton] built look great, but we love the modular design he adopted when building the circuit boards.

If you’re building something that is going to sit on your desk for some time it just has to look good. We think that he achieved that, using a small block of oak as the base, and a cloudy white cube of unknown origin as a diffuser. Notice that the different colors are not mixed. There’s a baffle inside the diffuser that keeps them separate as early testing showed any combination of intensities was resulting in nearly the same shade of color.

The part we really like is the modular design of his circuit boards. The project is based around a Teensy++ 2.0 board. He first built a PCB baseboard which feature two SIL sockets to accept the legs of the Teensy. There is a third SIL socket which accepts some long legs from the LED host board, letting it perch on top of the Teensy.

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Mailbox notifier texts when the letter carrier arrives


[Felix Rusu's] mailbox is on the other side of the street and he’s got a pretty big front yard. This means checking for mail is not just a pop your head out of the door type of activity. This becomes especially noticeable during the winter months when he has to bundle up and trudge through the snow to see if his letter carrier has been there yet. But he’s made pointless trips a thing of the past by building a notifier that monitors the mailbox for him.

He’s using a Moteino, which is an Arduino clone of his own making. It’s tiny and features an RF module on the underside of the board which takes care of communicating with a base station inside the house. The module seen above rolls the microcontroller board up along with a 9V battery and a hall effect sensor which can tell if the mailbox door is open or closed. When the Arduino detects a change to that sensor it pushes some data back to the base station which then relays the info to a computer or Raspberry Pi in order to send him a text message. All of this is shown off in the video after the break.

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Never miss your transport with this bus arrival notifier

[John Graham-Cumming] was all set to start a new project based on the Raspberry Pi. Well, that was until shipment was delayed due to manufacturing issues. Not to fret, he transitioned over to a router board which displays the arrival countdown for mass transit bus service.

He based the build on a web page the Transport for London provided. You can load it up and see if your bus is running on time or not. There’s no published API, but by studying the source code from the site [John] was able to figure out how the JSON commands were formatted.

The next step is building a standalone device to pull the data and display it. The board seen above is from a Linksys WRT54GL router. This longtime favorite has a serial port header which can be driven from the Linux kernel. He wired up a jack on the router’s case, and uses an extension cable to get from it to the 7-segment displays mounted in a model of the bus. Since there’s four digits the display can tell you minutes until the arrival of two different buses.

[Thanks Pseudo Lobster]

Boobie Board powered Twitter notifier


The team over at Archonix frequently challenge themselves to create a full working project in under 20 minutes. [Andrew Armstrong] put together a blog post detailing their most recent “Quickproject” – a simple Twitter notifier built using their Boobie Board.

They started by putting together a small notifier breakout module that could later be attached to their Boobie Board. The module is pretty simple and includes a trio of LEDs to alert you to activity across several online services, though only the Twitter notification module is currently complete. The notifier’s code was written in LUA, and primarily designed to interact with Linux desktops. They do not currently have a Windows compatible version of the code available, but they are more than happy to host it if someone desires to port their code over.

The notifier was put into an old candy tin with a plastic window, which is perfect fit for their project. All in all, the entire thing took them about 40 minutes, with half spent on hardware, half on code. The notifier does just what it was intended to do, but they have a healthy list of improvements that they would like to add, including the use of the other two notifier LEDs.

Twitter notifier lets us know how awesome we are


Let’s admit it, you’re just a little bit vain. Heck, we’re all just a little bit vain when you really think about it. Instructables user [pdxnat] was self-absorbed enough that he constructed an LED “mood light” that alerts him each time someone mentions his user name on Twitter.

The build is pretty simple, with most of the work being done on his PC. His Arduino is wired to a simple RGB LED that calmly cycles through various colors until someone mentions his name on Twitter. At that point, the client software running on his PC passes a message to the Arduino over a serial interface, causing it to wildly pulse the LED. Once it catches his eye, he stops the alert cycle with the press of the reset button, returning the LED to its previous state. As a bonus, he decided to write the Twitter-polling application in both Processing and Python, enabling fans of either language to easily replicate his work.

It’s a pretty cool idea, and it would be great to see someone expand it to include other online services to provide a greater overall feel for how awesome they really are.

Keep reading to see a quick video of the notifier in action.

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Facebook notifier uses some papercraft and simple electronics

This weekend project will tell you when you’ve got something new to look at on your Facebook page (translated). The yellow flag on the side of the mini-mailbox automatically goes up, alerting you to your recent online popularity.

[Rocco's] craftwork on this project is fantastic. We love the scale, the colors, and especially the artificial grass that adorns the base. Inside the mailbox an Arduino controls a small servo motor attached to the new mail flag. As with other Arduino-based notifiers (be it the Internet Furby, or our own troll sniffing rat) the USB connection makes it incredibly easy to convert online information to real-world signals. The client side of this is a Python script. It uses a package that we were previously unfamiliar with called mechanize. We’ve just made a cursory examination of how that package is used, but we’re going to keep it in mind as an alternative to our usual go-to package, BeautifulSoup, which tends to be a bit hairy when you’re just looking for some basic data.