Android Development 101 – Part 6:Getting Ready For Market!

In this tutorial we are going to cover packaging one of our applications into an .apk file and getting it ready for the Android Market.  After we have completed this tutorial you should be able to use the tools provided in the AndroidSDK to sign your application, put the application on your phone and install it or send it to the Android Market.  These will be great assets to have if you decide to develop applications that you may want to charge for.  This tutorial will also be a change from the normal ones because it will include little, if any, code.

Learn console hacking

This bright red handheld is [Bacteria’s] portable N64 console. We’re beginning to feel a bit saturated with N64 portable hacks, having seen one that looks like a Game Boy, another in a shiny black case, and yet another in a white case. This time around it’s not just the end product, but [Bacteria] has posted a saga discussing the build progress. Check out the 20 videos on his worklog page. If you’re looking to take existing hardware and put it into a different enclosure you should pour over this resource for ideas you can use.

PCB Toner Transfer With Dowel

Pulsar Professional FX has a neat tip on their site for getting a really even toner transfer when making your own PCBs. First, the PCB is cut to size, and the paper is tacked to the board. Then, the PCB is placed paper up onto a dowel and rolled back and forth with the iron. Since the board bends slightly over the dowel the toner sticks evenly to the copper. After that, just remove the paper as usual and etch with your preferred method.

Etch PCBs With Ferric Chloride And A Sponge

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Etching a printed circuit board generally takes a bit of time and uses a lot of etchant. [TechShopJim] posted a method that uses a sponge to reduce the amount of etchant used while speeding up the entire process. First, a resist is applied using either a sharpie or the toner transfer method. Using gloves to handle everything, he soaked a sponge in ferric chloride and continually wiped a copper-clad board until all the exposed copper was removed. This technique moves the etchant around more, keeping “fresh” etchant closer to the copper. If you can’t procure ferric chloride, you can also use our method that uses 2 household chemicals: hydrogen peroxide and hydrochloric acid.

Arduino Experimentation Kit

ARDX

[Oomlout] has created an Arduino Experimentation Kit that uses basic sensors, buttons, and LEDs to teach electronics and programming. Printed overlays are secured on a breadboard, indicating components and connections. The Arduino is then used to drive the circuit. Examples include driving motors, using shift registers, and making beeps with a piezo element. These are backed up by explanations and code. The breadboarding kit is very similar to the classic 300-in-1 project kits marketed to beginners. In addition, all of the materials are released as open source. Kits are also available that include everything needed to create the circuits.

Related: Opensource Robotic Arm

[via Hack a Day flickr pool]

Working With Relays

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SparkFun’s latest tutorial shows you how to work with relays. A relay is an electrically operated switch. In this case, they’re using it to switch a 120V AC outlet. The article carries the standard warnings about how not to kill yourself with AC (plus some non sequitor linking throughout). As an extra precaution, they chose a GFI outlet. You probably know how a relay works, but it’s worth seeing how they implemented it. They use a transistor to prevent overloading the microcontroller’s GPIO pin. The control pin is pulled to ground to keep the relay off. A diode is placed across the relay coil to manage the power flow when it discharges. An indicator LED is included to show when the relay closes. This is a great foundation for an automation project, or maybe you just want to terrorize your cat.