Adding Power Trim To A Boat

May 11, 2011 by Mike Szczys 16 Comments

[Matt’s] boat had a trim plate that could be adjusted by hand. The problem with this setup is that the trim angle of a boat changes as you speed up or slow down. Last year he never really went over 35 MPH because of this issue, but he set out to correct that by adding power trim plates for the upcoming boating season.

The original trim plate didn’t have a hinge on it, but simply flexed when tension was added to the adjustment hardware. [Matt] removed the plate and cut it into three parts; one long thin strip to serve as a mounting bracket, and two plates to independently adjust trim for the left and right side of the keel. Some aluminum strip hinges connect the three pieces, and a pair of used actuators acquired from eBay automate the trim adjustment. Each plate is strengthened by a pair of angle brackets, which also serve as a mounting point for the actuators. The final step was to add a pair of switches near the throttle lever which are used to make manual adjustments when the boat is in motion.

DIY Hidden Bookshelf Speakers

May 11, 2011 by Mike Nathan 10 Comments

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[Steve] was tired of looking at the speakers in his workshop and began searching around for something a little more aesthetically pleasing. Having recently received a set of hollowed out books used for hiding things as a gift, he thought that he might be able to solve his speaker issue in a similar fashion.

He grabbed a couple of books from a local thrift store and promptly removed the pages. They were replaced with cloth-covered plywood to make the device more sturdy while simulating the look of pages.

He mounted his speaker inside one of the books, and in a second installed a small 7W Class A amplifier. A third book houses a padded compartment to hold his iPod, completing the set.

[Steve] reports that the speakers are pretty much undetectable, and the sound quality is decent too. In fact, we’ve started looking for some old books to re-purpose in our workshop as well.

I2C 101

May 11, 2011 by Kevin Dady 15 Comments

Embedded Labs has come out with a very detailed I2C 101 tutorial, that you should check out if you have any questions on the system. I2C is a short distance serial interface that only requires 2 bus lines. Keep in mind that as wires go down complexity goes up. While there are more than a few I2C devices out there in the wild, and the 2 wire system does make wiring a breeze sometimes, the information required to make use of it often seems confusing to someone who is just starting with it.

The tutorial covers basic theory, stop / start conditions, addressing, data transfer, and acknowledgment plus illustrations. A couple of specific examples are given in the form of a 24LC512 serial eeprom, and a DS1631 digital thermometer complete with code.

Official Android Open Accessory Development Kit – It’s An Arduino

May 11, 2011 by Brian Benchoff 52 Comments

A new development kit for android was unveiled at the Google I/O 2011 developer conference that officially supports the Arduino.

It looks like Google took a cue from Circuits@Home, because the interesting part of this dev kit is the fact that the shield can be put into USB Host mode. That’s great for phones and tablets that can’t act as a USB host themselves. Google will also release the APIs for this Android/Arduino mashup for 3.1, but it will thankfully be backported to Gingerbread.

We covered the IOIO breakout board for Android last month, but the Google board will be based off of the Arduino Mega 2560, a far more capable device. Interestingly, it appears this board is available now for about $400 USD. We’re not so sure a hobbyist will be buying it at that price.

While this board doesn’t do anything you couldn’t do before with a bluetooth shield, it’s great to see a company supporting all the builders out there.

Machining Replacement Parts With Hand Tools

May 11, 2011 by Kevin Dady 18 Comments

Jeff is a huge music fan, and like many of us likes old technology, so it seemed a bit silly (to him) that he did not have a turn table. His dad had a spare in the basement. A neat old Braun model from the 1970’s that was broken.

Opening the unit up he found that part of the arm mechanism was broken, and thanks to the age of the turntable and the wonders of mass production chances of finding a replacement were slim to none. Not being discouraged he busted out the hand tools and fabricated the replacement out of some aluminum. The end result is a perfectly functioning turntable that will serve many more hours pushing out warm jams.

Check out the fourm post above to get details and pictures, and we just wanted to tell [Jeff], awesome job!

Arduino Magnetic Core Memory Shield

May 11, 2011 by Mike Nathan 14 Comments

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Magnetic core memory turns 60 years old today, and as a tribute [Ben North and Oliver Nash] have created a 32-bit magnetic core memory board for the Arduino.

Magnetic core memory was used from the 1950s through the 1970s, and provided a non-volatile means for storing data, as each magnetic core retained its orientation, even when the power was cut. While it sounds a lot like a modern hard drive, these devices were used in the same fashion as RAM is utilized today.

While the pair used surplus ferrite cores manufactured just before magnetic memory stopped being produced, they did allow themselves to use some modern components. Items such as transistors and logic gates were not available to the first magnetic core memory manufacturers, but the use of these items helped them complete the project in a reasonable amount of time.

Their final result is a magnetic memory board which can be used by any USB-enabled device and is reliable enough to withstand billions of read/write transactions.

Cheap Open-source Pace Clock Keeps Your Practice On Schedule

May 10, 2011 by Mike Nathan 10 Comments

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Pace clocks are used in a variety of sports, from swimming to track. The systems are typically expensive however, often beyond the reach of smaller organizations and underfunded programs. For their electrical and computer engineering final project, Cornell students [Paul Swirhun and Shao-Yu Liang] set out to build a much cheaper alternative to commercial pace clocks, with a far simpler wireless user interface.

Their clock uses an ATmega32a to handle all of the processing which is paired with a RN-42 Bluetooth module for communicating with Android smartphones. Their seven-segment displays are built using custom PCBs that they designed and fabricated for the project which are controlled by TLC5940NT LED drivers. The Android software allows users to connect to the pace clock remotely, creating any sort of multi-layered swimming or running routines.

When the project was completed, the pair tallied their total hardware cost to be under $250 apiece at low production volumes. Even when taking assembly time into account, their solution is several magnitudes cheaper than similar commercial systems.

Stick around if you are interested in seeing a demo video of their final product in action.

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