Electronics Everything Reference Poster


[Ben] just sent us this great reference sheet. It’s a poster he compiled of datasheets and various electronic references. He made it after spending too much of his time sifting through datasheets while working on projects. It also helped that he realized his school, Georgia Tech, had a poster printing service!

It contains the basics from resistor color codes, typical pinouts of various chips, current capacity of wire gauges, Arduino pinout diagrams, schematic symbols, trace widths for current capacity, and even typical coding functions!

The full image is 9,000 x 6,000 pixels and will print nicely at 30 by 20 inches, just shy of the ANSI D paper size. It’s 6.1MB so only click here if you want it!

Maybe if we ask nicely he’ll share the original MS Publisher file so we can tailor it to our individual needs! Some of the text in the images is a bit blurry, but everything is basically still readable.

Headphone Hack Makes Wireless an Option


If you have a favorite pair of over-the-ear headphones you may want to consider upgrading them with a wireless option. The key word here is “option” because these still retain their functionality as a wired headphone. This is nice if you only want to deal with battery life when you’re actually roaming around.

Of course the thing that makes this type of hack work is the extra room inside the body of the earpieces. [Tony] cracked them open and decided there was just enough room to fit the internals of a Bluetooth audio adapter. It has it’s own Li-ion battery (boasting 12 hours of use) which is why there is an added charging port. To fit the board he had to remove some of the aluminum body from the enclosed part of the headphones. He also wired up a tactile switch to act as the power button for the Bluetooth module.

Details are scarce on how the speakers are wired between the module and the jack. But we think he simply wired them in parallel rather than using a switched jack. You can see a quick demo after the break but it really doesn’t augment the build details at all.

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Touring Component Markets in Shenzhen


[Al] recently returned from a trip to China. While there he toured some of the component markets in Shenzhen, the electronics assembly epicenter of the world. While he doesn’t focus too closely on what is actually being sold there, we found his description of the markets themselves and other notable attractions around the area quite interesting.

Shenzhen is different from some of the other component wonderlands we’ve heard about ([Ian Lesnet’s] tour of Akihabara in Japan comes to mind). First of all it may be a bit more difficult to get there. US Citizens need a Visa to enter China, and must fly to Hong Kong and take a ferry to the mainland. [Al] reports that the traffic is horrendous and rush-hour can turn a ten mile ride that usually takes ninety minutes into a three hour tour… a three hour tour!

The side affect of the market being out of the way is that the prices aren’t as inflated as they may be in more geek-tourist-friendly locations. That being said it also sounds like the vendors are interested in selling you a few thousand units rather than a single component. Follow the link at the top for the market tour, a stop at Seeed Studios (who will apparently sell you a map of the best markets to visit), and the rest of the attractions that [Al] encountered.

Breadboard Tetris is Wire Artwork


Look closely at the colored pixels on this pair of 8×8 RGB LED modules and you’ll be able to pick out some of the familiar shapes of Tetris pieces. It’s impressive that [Jianan Li] built his own color Tetris including the theme music, but look at this breadboard! The layout of his circuit is as equally impressive as the code he wrote to get the game up and running. It takes a fair amount of planning to get a circuit of this complexity to fit in the space he used, right?

There are two microcontrollers at work, each running the Arduino bootloader. The main chip is an ATmega328 which is responsible for monitoring the buttons and controlling game play. The other is an ATmega85. The eight pin chip listens to it’s bigger brother, playing the theme song when the game starts, and pausing or resuming to match the user input So is the next stop for this project playing Tetris on the side of a building?

Don’t miss the demo video after the break. We’ve also rolled in a video of his Arduino-based piano. It’s built on a breadboard that’s nearly as impressive as this. But what delights us is his skill at playing Pokemon themes on the two-octave tactile switch keyboard. Obviously those piano lessons his parents shelled out for really paid off!

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Custom E-Cruiser has features for disabled rider


As [AussieJester] noted in the first page of his build log, most people’s idea of a “custom-made” electric bicycle involves strapping some electronics and a hub motor onto any off-the-shelf bike. He needed a bigger challenge, so he fabricated his own frame to build a stylish electric cruiser. This bike has a 2-speed transmission and a massive Turnigy 80-100 brushless outrunner motor, which pushes out a top speed of 45mph.

You may have noticed what look like training wheels in the picture above, and you’d be half-correct. [AussieJester] is a paraplegic, and needed to guarantee some stability both when transferring from his wheelchair and when coming to a stop. The best feature of this bike, however, is that these small wheels are retractable. A linear actuator lowers them for slower speeds and for mounting/dismounting, but picks them back off the ground once you are up to speed, maintaining a true 2-wheeled experience.

Stick around for a couple of videos after the break: a first-person POV showing just how quick this bike can move, and a demonstration of the actuators. Then check out another EV pioneer in the world of skateboarding.

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[Kyle] wanted to try something new. A Persistence of Vision Clock using a CD-ROM drive.

We have covered lots of POV Clocks that make use of hard drives, but we think this is the first time we have seen a CD-ROM drive used instead. [Kyle] points out that CD-ROM drives are typically much quieter than hard drives, which is the main reason he chose the CD-ROM route.

At the heart of this project is a good old ATMEGA168 and an RGB LED strip for the lights. To measure and maintain the rotational speed of the clock [Kyle] used an IR photodiode that detects a reference mark on the disc. An elegant build of a classic POV Clock, with a new twist!

The cool thing about this project is he did not actually use the CD-ROM drive like you think he would — he chucked the spindle motor and instead is spinning the disk using the tray ejection motor! He did this so he could control the motor by PWM straight off the microcontroller, whereas the spindle motor would require an IC and a varying control signal with specific voltage amplitudes.

He also experimented with different backgrounds and background lighting, which you can see in the video after the break!

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DIY Metal Detector

Looking for a light project to teach young hackers some very basic electronics? Here’s a quick and easy weekend project, a simple metal detector!

We all know 555 timers are very useful and pop up in a wide range of projects, but did you know a metal detector is one of them? [vonPongrac] stumbled upon this handy guide, a free eBook on 50 555 Circuits, which contains many cool project ideas, including a simple metal detector circuit. It’s a very basic concept that uses a coil of copper wire as a home-made choke — when metal or a magnet comes near the coil, it varies the output frequency, and the 555 timer in turn, varies the output sound, alerting you of the presence of something metal nearby.

After the break there’s a video of it during its testing phases. If you don’t have a 555 on hand (tisk tisk) but still want to have some treasure hunting fun you can also build one based on an Arduino.

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