Ask Hackaday: Dude, Where’s My MOSFET?

December 13, 2016 by 126 Comments

(Bipolar Junction) Transistors versus MOSFETs: both have their obvious niches. FETs are great for relatively high power applications because they have such a low on-resistance, but transistors are often easier to drive from low voltage microcontrollers because all they require is a current. It’s uncanny, though, how often we find ourselves in the middle between these extremes. What we’d really love is a part that has the virtues of both.

The ask in today’s Ask Hackaday is for your favorite part that fills a particular gap: a MOSFET device that’s able to move a handful of amps of low-voltage current without losing too much to heat, that is still drivable from a 3.3 V microcontroller, with bonus points for PWM ability at a frequency above human hearing. Imagine driving a moderately robust small DC robot motor forwards with a microcontroller, all running on a LiPo — a simple application that doesn’t need a full motor driver IC, but requires a high-efficiency, moderate current, and low-voltage-logic compatible transistor. If you’ve been here and done that, what did you use?

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Pioneer AVIC Infotainment Units Hacked To Load Custom ROMs

December 13, 2016 by 23 Comments

Pioneer’s flagship AVIC line of in-car multimedia systems is compatible with both Android Auto and Apple Car Play, and offers all manner of multimedia features to the driver of today. What’s more, these in-dash wonders have spawned their own community, dedicated to hacking the units. The ultimate infotainment hack is to develop custom ROMs for these devices.

What this means is that owners of Pioneer AVIC units will eventually be able to flash a custom ROM onto their in-car device, allowing it to operate more like any other generic Android tablet on the market. The potential is there for installing custom applications, extra hardware (such as OBD II readers), or pretty much anything else you can do with an Android device.

The hack involves a whole lot of delicate steps, beginning with using a USB stick with a special image to boot the device into a test mode. This allows the internal SD card to be backed up, then overwritten with a new image itself.

Mostly, the hack has been used to allow map files to be updated on the internal SD card — inability to update maps has been a long festering thorn in the side of in-dash navigation systems. Users have been customizing this to suit their requirements, also adding speed camera locations and other features. But overall this hack is a great example of hacking something to get full control over the things you own. At the least, this will allow drivers to ditch the phones suction-cupped to the windshield and run common apps like Waze, Uber, and Lyft directly on the infotainment screen (assuming you can rig up an Internet connection).

Check out another great Android ROM hack — using a cheap old smartphone as a low-cost ARM platform.

Be Your Own Google Mapper

December 13, 2016 by 13 Comments

Google Maps is one of the modern wonders of the world. It is hard to remember how expensive it used to be to get high-quality aerial  images. Of course, you don’t get to pick when they fly over a particular piece of the planet. If you are like [Dennis Baldwin] that’s not good enough. He’s been using his drone to document the construction of a high school stadium.

[Dennis] uses the open-source GDAL tools to create Google Map tiles from drone imagery. Even better, he’s documented the process in the video you can find below. Once you can make your own map tiles, you can control when you take the images — important if you are documenting construction like [Dennis] did.

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Modify Locks To Baffle Burglars

December 12, 2016 by 63 Comments

While it’s often thought of as a criminal activity, there’s actually a vibrant hobby community surrounding the art of lock picking. In the same way that white hat hackers try to break into information systems to learn the ways that they can be made stronger, so do those in the locksport arena try to assess the weaknesses of various locks. For the amateur, it can be exciting (and a little unnerving) to experience the ease at which a deadbolt can be picked, and if your concern is great enough, you can go a little farther and modify your locks to make them harder to defeat.

The lock in question was sent to [bosnianbill] by [Rallock67] with a device that [Rallock67] had installed using common tools. Known as a Murphy Ball, a larger-than-normal spring was inserted into one of the pins and held in place by a ball bearing. This makes the lock almost completely immune to bumping, and also made it much more difficult for [bosnianbill], an accomplished and skilled locksmith, to pick the lock due to the amount of force the spring exerted on the cylinder. The surprising thing here was that this modification seems to be relatively easy to do by tapping out some threads and inserting a set screw to hold in the spring.

Locksport and lockpicking are a great hobby to get into. Most people start out picking small padlocks due to their simplicity and ease. It’s even possible to pick some locks with a set of bobby pins. And, if you really want to see how easy it is to defeat some locks and/or how much good the TSA does for your overall security, you’ll want to take a look at this, too.

Thanks to [TheFinn] for the tip!

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Use Machine Learning To Identify Superheroes And Other Miscellany

December 12, 2016 by 6 Comments

[Massimiliano Patacchiola] writes this handy guide on using a histogram intersection algorithm to identify different objects. In this case, lego superheroes. All you need to follow along are eyes, Python, a computer, and a bit of machine learning magic.

He gives a good introduction to the idea. You take a histogram of the colors in a properly cropped and filtered photo of the object you want to identify. You then feed that into a neural network and train it to identify the different superheroes by color. When you feed it a new image later, it will compare the new image’s histogram to its model and output confidences as to which set it belongs.

This is a useful thing to know. While a lot of vision algorithms try to make geometric assertions about the things they see, adding color to the mix can certainly help your friendly robot project recognize friend from foe.

 

Modular Tap-Dancing Robot Can Shuffle Ball Change

December 12, 2016 by 7 Comments

Electromechanical solenoids are pretty cool devices. Move some current through an electromagnet and you can push a load around or pull it. If you’re MIT student [Lining Yao], you can use them to dance. [Lining] built TapBot, a re-configurable set of tap-dancing robots that are both modular and modern. She even rolled her own solenoids.

The one with the eye stalk is the bridge, and it’s connected to a computer over FTDI. The other nodes attach to the bridge and each other with small magnets that are designed to flip around freely to make the connections. These links are just physical, though. The nodes must also be connected with ribbon cables.

Each of the nodes is controlled by an ATtiny45 and has a MOSFET to drive the solenoid at 8-12 V. [Lining] snapped a small coin magnet to the end of each solenoid slug to provide a bigger surface area that acts like a tap shoe. TapBot can be programmed with one of several pre-built tap patterns, and these can be combined to make new sequences. The curtain goes up after the break.

There are other ways to make things dance, like muscle wire. Check out this whiteboard pen that uses nitinol to dance to Duke Nukem.

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More Blinky = More Better – The WS2812FX Library

December 12, 2016 by 16 Comments

The WS2812 is an amazing piece of technology. 30 years ago, high brightness LEDs didn’t even exist yet. Now, you can score RGB LEDs that even take all the hard work out of controlling and addressing them! But as ever, we can do better.

Riffing on the ever popular Adafruit NeoPixel library, [Harm] created the WS2812FX library. The library has a whole laundry list of effects to run on your blinkenlights – from the exciting Hyper Sparkle to the calming Breathe inspired by Apple devices. The fantastic thing about this library is that it can greatly shorten development time of your garden-variety blinkables – hook up your WS2812s, pick your effect, and you’re done.

[Harm]’s gone and done the hard yards, porting this to a bevy of platforms – testing it on the Arduino Nano, Uno, Micro and ESP8266. As a proof of concept, they’ve also put together a great demonstration of the software – building some cute and stylish Christmas decorations from wood, aluminium, and hacked up Christmas light housings. Combining it with an ESP8266 & an app, the effects can be controlled from a smartphone over WiFi. The assembly video on YouTube shows the build process, using screws and nails to create an attractive frame using aluminium sheet.

This project is a great example of how libraries and modern hardware allow us to stand on the shoulders of giants. It’s quicker than ever to build amazingly capable projects with more LEDs than ever. Over the years we’ve seen plenty great WS2812 projects, like this sunrise alarm clock or this portable rave staff.
As always, blink hard, or go home. Video after the break.

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