It’s not everyday that we review software around here, but the folks at Adafruit recently put together an iOS app that I figured might be of interest. Their iPad/iPhone compatible application is called “Circuit Playground”, and it includes all sorts of handy electronics reference tools. For the context of this review, it should be noted that I paid for the application myself, and that I have had no communication with the Adafruit team regarding my assessment of the app.

As you can see from the main screen, the app currently features eight different tools, not counting the “Deals @ Adafruit” entry, since I consider that to be more of a marketing strategy than a real tool. The rest of the items are pretty standard reference fare, in an easy to use and understand package.

The Resistor Value tool is pretty straightforward, allowing you to specify resistance in two ways. You can select the color bands of your resistor and view the resulting value, or enter the resistance to see what color resistor you should be looking for. It supports both 4 and 5 band resistors as you would expect, and features a simple “Instruction Page” (as do all the tools), accessible via the small information icon on the bottom left corner of the screen. One thing I would love to see implemented is the ability to photograph components and display their resistance. I think it would be a very helpful addition for makers whose eyesight isn’t what it used to be.

The Multiple Resistor and Multiple Capacitor tools are similar in function, showing you the resultant resistance/capacitance of various series and parallel component setups. They both support up to 9 items apiece, and let you select the capacitance and resistance values for each component one at a time. This is both good and bad, as it gets pretty tedious entering each value manually after a bit. One other item that I thought could use improvement here was the functionality of switching between series and parallel configurations or adding/removing components. Any time a change is made to the configuration, all of the values are reset – this means that if you add another resistor to your 8-resistor diagram, you must re-enter each and every value.

The LED Resistor Calculator does exactly as its name suggests, much like many online calculators that have come before it. This handy feature lets you pick your LED color from a pre-determined list, populating the forward voltage and current fields automatically, based on some common/standard values. Once you specify a supply voltage and quantity of LEDs, the application returns the exact resistance required to meet your specs, along with the value of the nearest standard resistor. While the tool is certainly helpful when calculating resistors for LEDs in series, it lacks any sort of ability to do the same for parallel configurations. If the folks at Adafruit included that functionality along with the ability to customize the default LED list, I would be thrilled. I do have to point out however, that this tool does retain the LED count and supply voltage when changing LED colors, which is something I was glad to see after playing around with the Multiple Resistor tool.

The Ohm’s Law calculator is a simple tool that is great for allowing me to carry out quick sanity checks of the math I have done in my head. Simply enter two values in the triangle, and Circuit Playground spits out the third. The Power Calculator is a similarly straightforward tool, which takes in two of four values (Power, Voltage, Current, Resistance), calculating the rest for you. Neither tool is overly complicated, but then again they don’t need to be.

The final calculator that the app provides makes number conversions dead simple. Given one number, the converter will give you its representation in binary, decimal, hexadecimal, octal, and ASCII notation. While it might not be something that I’ll use every day, it certainly is a very helpful reference tool. I personally think that this tool would benefit from the ability to convert strings of characters/numbers rather than one at a time, but perhaps that is something they are looking to add in a forthcoming release.

One of Circuit Playground’s features that is not as prominent as the others on the main menu is the built-in datasheet viewer. It uses a lightweight interface to help search through and view PDF files located in the iPhone’s document store. I don’t have anything of the sort stored on my phone so I can’t truly test this portion of the app – let us know in the comments how it works for you.

A few data persistence nitpicks aside, I think that Circuit Playground is a solid app with a lot of potential. At $2.99 it sits at the higher end of the App Store pricing structure, so whether or not these tools are worth it is ultimately up to you. Adafruit does say that anyone who purchases the app gets $3 off their next order in their online store, which essentially makes the app free if you are a regular customer.

While it’s not designed for your seasoned Electrical Engineer, it is definitely a great resource for the part-time tinkerers out there. At the moment, it is an iOS-only offering, but Adafruit says that they will be releasing an Android version at some point in the future. In the meantime, they suggest giving ElectroDroid a try, as it is currently the best app on that platform.

[Tod’s] daughter has a habit of forgetting to take a house key along with her, so he was looking for a way to make accessing the house easier in a pinch. He had tried wireless garage door keypads in the past, but their performance was so-so at best. After scouring the market for commercial solutions and checking out the work of other hackers, he decided that he needed to craft a custom solution of his own.

He started shopping around for wireless-enabled microcontrollers and settled on a Roving Networks RN-XV module, which is designed as a drop-in replacement for an XBee. Paired with a 5v to 3.3v power adapter, the RN-XV is nearly all he needed to interface his iPhone with his garage door opener.

The microcontroller has enough GPIO pins to control the garage door, while also monitoring the door’s status using a simple magnet/reed switch combo. A web server in [Tod’s] house takes input from any phone connected to his wireless LAN and relays the open/close commands to the opener. The opener in turn returns status messages to him via the web interface.

We really like the system’s simple design, and as long as [Tod] has turned WPS off at home, he really shouldn’t have to worry too much about unauthorized entry.

Admittedly this post is flirting with flamebait, but we think the concept of using a spring clamp as an iPhone tripod mount has a lot of hacking potential. Hear us out, and if we havn’t made our case you can rant about it in the comments.

[Joe] wanted an easy way to mount his iPhone on a standard tripod. We’ve seen some creative solutions for this, like using Sugru to make a removable bracket. But he went a different route, using a cheap spring clamp to grip the phone body. These plastic clamps are like over-powered clothespins, and use a screw as the pivot point. [Joe] replaced the stock screw with a longer one, then used a coupling nut which will attach to the tripod. A bit of foam on the pads of the clamp protect your device from the plastic teeth.

It’s a fine solution (if you don’t mind putting that pressure on your smart phone). But we think this would be a great way to build your own heavy-duty third hand. It would be right at home with this modular solder platform. See [Joe's] how-to video embedded after the break.

Hack a Day alum [Will O’Brien] recently upgraded his phone, and was trying to find a use for his old one. He always wanted a remote starter for his Subaru Outback, but wasn’t interested in paying for an off the shelf kit. Since he had this old smartphone kicking around, he thought that it would be the perfect starting point for an SMS-triggered remote start system.

He started off by jailbreaking his phone, which allows him to run some Perl scripts that are used to listen for incoming texts. Using a PodBreakout mini from Sparkfun he connected the phone to an Arduino, which is responsible for triggering the car’s ignition. Now, a simple text message containing the start command and a password can start his car from a anywhere in the world.

While [Will] is quite happy with his setup he already has improvements in mind, including a way for the Arduino to send a message back to him via SMS confirming that the car has been successfully started. He’s thinking about putting together a kit for others looking to add the same functionality to their own car, so be sure to check his site periodically for project updates.

When [Peter] saw the Sparkfun Magician robot chassis in a recent new product post, he knew instantly that he had to have one for a telepresence project that had been kicking around in his head for a while.

Onto the robot chassis, he added an Arduino to provide the brains of the bot, an Adafruit motor shield for controlling the wheels, and a Pololu Wixel for wireless communications. An iPhone is mounted on the top of the robot, which communicates with his laptop using Apple’s Facetime app. The robot is controlled from his laptop as well using the Wixel, which enables him to direct the Magician chassis as if it was attached via USB.

While he thinks the robot is pretty neat and that it works well, [Peter] already has improvements in mind. The robot chassis is a bit weak on anything but smooth surfaces, so a new set of motors and wheels are likely the first changes he’ll make. He wants to add a servo-based aiming mechanism for the phone’s camera, as well as some sensors to prevent the bot from taking a nosedive off his table.

iPhone aside, this is probably one of the cheaper mobile telepresence setups we’ve seen, so we can’t wait to hear how the improvements work out, and how much they add to the robot’s cost.

It’s no secret that the audio quality of the iPhone’s built-in speakers isn’t exactly what you would consider to be hi-fi. Sound quality aside, there are plenty of times where even the volume doesn’t do the music justice. While you can always go out and buy a fancy dock to amplify your iGadget’s sound, artist [Christopher Locke] has a different take on the subject.

For a while now, he has been constructing what he calls “Analog Tele-Phonographers”, metal sculptures that can be used to amplify a mobile phone’s audio. Built out of steel and old trumpets, his audio sculptures require no electricity, instead utilizing the same amplification technology as the original phonographs.

While the Tele-Phonographers won’t make your iPhone sound like a high quality tube amp, they do undoubtedly increase the phone’s volume and they are nice to look at. We can certainly get behind this sort of recycling/reuse of old items.

Continue reading to see a quick video of his Analog Tele-Phonographer in action.

[Thanks, Chris]

This Daft Punk helmet replica is beautiful to look at, but the deeper we delve into the build process, the more we begin to think that the entire project is a piece of artwork. [Harrison Krix] has been working on it for months, and just posted his three-part build log in September. Check out the video and the links to all three parts after the break.

Now [Harrison] isn’t new to prop replica scene. He’s the guy responsible for the other fantastic Daft Punk helmet we saw last year. He’s tapped the same fabrication skills to churn out an equally impressive chromed helmet, complete with addressable flashing LEDs. He built his own mold to create the body of the helmet, reminding us of the Storm Trooper helmet replicas we saw in July. While this was off being coated in chrome, he got down to business with the electronics.

The visor of the helmet has a red LED marquee. This, along with the multicolored visor sides and ear pucks, is controlled by an Arduino yellow jacket. The lights can be controlled by an iPhone app that connects to the helmet via WiFi, letting a user push custom messages to the display, and alter the light patterns. The build shines on the inside as well as the outside with an incredibly clean LED matrix build, and clever control placement for switching each part on or off.

Build Log Links:

• Part 1
• Part 2
• Part 3

[Sepehr] didn’t have a coffee maker, and the local coffee shops were all out of joe. He got his fix by making a drip coffee maker out of disposable cups and knives.

Flexible braille display

Thin film technology is being developed to help the visually impaired. This flexible OLED display has embedded muscle cells which create a braille display. [Thanks Aaron]

Printable iPhone tripod mount

Looking to make those iPhone videos a little more stable, and the pictures a little less blurry? Try out this printable tripod mount that [Chris] came up with.

Arduino macro photos

Speaking of photographs, [Daniel] wrote in to share some macro pictures he took of an Arduino. They’re sure to be of interest to those readers who love everything Arduino.

Carpeting a mouse

Add a unique texture to your mouse by covering part of the body with fabric. The lower half of the mouse case above is covered in a carpet-like material [translated]. [Thanks Clicker]

[Jean] was shopping around for a vintage stereo receiver, and happened upon a broken, but repairable Marantz 4240. After getting things back to working order, he thought it would be great if he could use his iPhone to remotely control the unit (PDF Writeup, Schematics and Code).

He scrounged around for parts, and after locating a PIC and a handful of parts from old copiers and printers, he got down to business. He etched some custom boards to house electronic bits, then strapped motors to the volume and source selection knobs. He also rigged up the push button power switch on the receiver, using a small servo and a bit of string.

Now, he can control everything using his iPhone, which communicates with the stereo over WiFi. While the power, volume knob, and input selector can be triggered remotely, he still has the ability to tweak any of these items manually if desired.

We think that this is a great way to add modern amenities to vintage electronics, without ruining the aesthetics of the components. Don’t take our word for it though, check out the video demonstrations [Jean] but together after the jump.

[Alex Busman]‘s first foray in iOS programming looks like a pretty useful tool. He came up with Ohm Sense, an iPhone app that will take a picture of a resistor and calculate the value based on the color bands. It’s a great tool that we wish we had when we were starting out. At 99 cents, the app is also much cheaper than the emotional cost of our relationship with Violet.

[Alex]‘s used OpenCV for processing of the image data. The app works by scanning the image from the top-left corner and continuing until it sees a beige rectangle. After a bounding box is drawn around the resistor, the iPhone scans the image for columns of color. After a little interpretation, the value of the resistor is displayed on the screen. While it only works on resistors with beige plastic now, [Alex] says he’ll expand that in the future to include blue bodied metal-oxide resistors. [Alex] says the coding only took a week, so if anyone would like code a similar app for Android, be sure to tell us on our tip line.

This isn’t [Alex]‘s first Hack A Day build. We featured his Handy Board project that uses an NES controller to play some chiptunes earlier this summer. Compared to the projects we’ve let slip over the last few months, it’s good to see someone did something productive with their summer.

[Alex] posted a demo of his resistor app on YouTube. Check it out below.

We’re still waiting for our [Lt. Uhura] style earbuds. But until then, can we interest anyone in a set that will stand up to some abuse?

Solder Pot Scavenger

[Felicitus] says we should get a solder pot and use it to scavenge for parts. His method looks pretty easy and it’s cheaper than buying a rework station for this purpose.

Smartphone cooling

Turn all your hacking skills loose to beat the heat. That’s what [Stephanie] did when she added iPhone control for an oscillating fan.

Tunes calculator

Graphing equations and crunching numbers wasn’t enough for [Drew]. He went and figured out how to make his TI-84+ play music off of a thumb drive.

Geek-chic

Don’t let anyone out-geek you at company parties. Beef up your arsenal with this resistor color-code necktie. And yes, you can wear it with a T-shirt!

The iWallet is a slick little device if you’ve got a big wad of cash burning a hole in your pocket. The $600 price tag was a little much for [cmw] to swallow, so he bought a water damaged iWallet on eBay with hopes of repairing it. Once took a close look, he knew that repairing it was a lost cause, so he decided to hack it instead.

He pulled out most of the wallet’s electronics save for the motor that opens the device, and replaced the damaged parts with his own. He installed an Arduino pro as well as a Bluetooth module, powering the pair with a small rechargeable LiPo battery. The iWallet’s fingerprint reader was then replaced with a series of LEDs that show the device’s Bluetooth connectivity status.

[cmw] can now connect his wallet to his phone, issuing unlock commands via Bluetooth. If you don’t want to fork out the cash, his version is nearly as good as the real thing.

Continue reading to see a quick video of [cmw’s] iWallet hack in action.

When Google released their ADK allowing Android smart phones to interact with Arduino-based devices, we’re sure there were at least one or two iPhone users who felt left out. Thanks to the folks over at Redpark, those people can now interact with an Arduino without having to jailbreak their phone.

For anyone looking to do any sort of iPhone/Arduino interaction, this is a good thing – except for the price. The 30-pin to serial cable is currently available over at Make for $59, which honestly seems pretty steep to us. When we first saw this announced, our initial thoughts were that we would see an open-source version in no time.

Unfortunately, that idea was short-lived, as we were quickly reminded of Apple’s MFI program. If you are not familiar, MFI (aka Made for iStuff) program limits what can be connected to an iDevice via licensing fees and a boatload of legal agreements. While we won’t be picking up this dongle any time soon, we’re all ears if someone has done any reverse-engineering of those pesky MFI chips.

While it seems that many people are wise to shoulder surfing, keeping a lookout for anyone spying on their passwords, [Haroon] wrote in to remind us that the threat is just as real today as it ever was.

The subjects of his research are touch screen phones and tablets, which utilize on-screen keyboards for data entry. He says that while nearly all password entry boxes on these devices are obscured with the traditional line of asterisks, the keyboards themselves are quite an interesting vulnerability.

Since touch screen technology can be finicky at times, most vendors ship their devices with some sort of key press verification system. On the iPhone and iPad, for instance, each key is highlighted in blue following a button press. This functionality makes it quite easy for shoulder surfers to casually steal your password if you’re not paying attention.

But what if you are well aware of your surroundings? [Haroon] has developed a piece of software he calls shoulderPad, which is based on openCV that does the surfing for him. The application can monitor a video stream, live or recorded, extracting the user’s password from the highlighted button presses. His demonstrations show the recording taking place at a relatively close distance, but he says that it would be quite easy to use surveillance footage or zoom lenses to capture key presses from afar.

He does say that the button highlighting can be easily disabled in the iPhone’s options pane, which should negate this sort of attack for the most part.

Continue reading to see a quick video of shoulderPad in action.

[Tim Thaler] has been redoing his home, adding some fancy automation here and there. But when it came to the kitchen, he went all-out by installing an iPhone controlled disappearing island. In the video clip after the break you can see [Tim] dial up some extra counter and storage space from his smart phone. One click causes it to slowly rise from the depths, shedding the carpet tiles as it goes.

Directly beneath the kitchen is an unfinished storage room. [Tim] framed a hole in the floor above, and sourced a used scissor lift for about $380 to do the heavy lifting. It operates smoothly and isn’t all that loud. It sure makes for an interesting feature if he ever decides to sell the place.

We thought it was a nice touch that the storage room hiding the mechanical parts of the hack has a hidden entrance. You must travel through the billiards room in the basement to access it, turning the ball rack to unlatch the entrance.

[Thanks Mallie]