Top 10 iPhone apps for electronics hackers


There are so many apps available for the iPhone, one might even say there are a plethora. We would like to take a moment to help you find a few that might help with your hacking projects. Ever have problems remember a formula when you need it? Need to track the acceleration of your brand new rover? How about beginners needing help remember resistor codes. Well, there’s an app for that. Check out our suggestions after the break.

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Tiny GSM alarm system

We’ve covered this sort of thing before, but there is something to be said for the simplicity of this tiny GSM alarm system by [trax]. The alarm system is designed to send the owner a text message when a sensor is triggered. This alarm only works with Siemens phones, but it shouldn’t be too hard to find one.  The alarm is configured via a dip switch on the board and can also be armed and disarmed by text. The brains of this system is a PIC16F84A. The code and schematics are included at the bottom of the page.

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USB gameboy cart


[Jose Torres] sent in his latest attempt at creating a custom Gameboy game cartridge. We’ve featured his projects before, and he’s come a lot closer over the last 2 years. He’s aiming to create an easy interface for homebrewers that doesn’t require any other special equipment. In this revision, he’s using a PIC and a memory controller to interface between an SD card and the Gameboy. The cart also has USB support for uploading files to the SD card and reprogramming the PIC. Because it’s just USB mass storage, it will work on almost any modern OS. He’s currently testing the device, but hopes to be selling them soon for $40.

Interfacing a digital rotary switch


[hw640] has put together a well written and detail packed explanation of how to interface with a digital rotary switch. These digital opto encoders have just two outputs with four possible logic levels (00, 10, 11, 01). The relative position of the switch is insignificant but the direction of rotation is what matters.

The short and dirty: Each of the switch’s 2 output pins is attached to a pin change interrupt on the microcontroller. Every time the switch moves it generates either a rising edge or a falling edge on one of the two pins; both edges cause an interrupt. By checking which pin caused the interrupt, then comparing the logic levels of the two pins after that interrupt, we can determine the direction the switch was rotated.

Although this explanation uses a PIC and code written in PicBasic Pro the concepts are discussed in the abstract and would easily be adapted to an AVR or another microcontroller of your choice.

Collect and analyze ECG data


Although we’ve covered DIY ECGs before, [Scott Harden] sent in his version that gives an in-depth explanation of what to do with the collected data. He built a basic battery-powered op-amp-based ECG for under $1. The circuit just amplifies the signal from the chest leads and feeds it into a computer via the microphone port. He then used GoldWave to record, filter, and save the signal. From there, he used python to analyze the heartbeat and calculate his heart rate and further manipulate the data. His previous blog posts go into more detail on how the python code works and why he chose software over hardware filters.

Teardown of the Barista


iFixit has done a tear down on the symbolic do-it-yourself Espresso machine, the Starbucks Barista. Believe it or not, there is not a single circuit board in the works. There doesn’t seem to be much to the Barista; A few switches, some solenoids, a heater, and one way spring valve among other things. The assembly of the device is very simple. It is noted that in a pinch it may be torn down with a pair of pliers and washer; in place of a flat head screw driver. We have pondered the possibilities of this machine numerous times, while enjoying a cup of cappuccino. Though most conversations end at the bottom of the cup, many survive such as this Silvia PID looped expresso machine. The very name “Mecha turbo crazy coffee roaster” seems to encapsulate the effects of caffeine quite adequately.

Solid state tesla coil


While researching solid state Tesla coils we stumbled across this old project. As you have probably guessed from the pictures, this coil is meant to actually play music. Knowing how to add eye catching flare, the coiler uses a Plexiglas frame turned light pipe; only to be complimented by an audio amplifier complete with graphic equalizer. There is a video of the coil in action on YouTube. We have covered singing tesla coils in the past. Other twists on the classics include the tesla coil guitar amp and a hand held plasm gun.