The Quest For A Bicycle Power System

[Garote] has been extremely busy. Busy building an electrical system into his bicycle, and even busier writing a monumental post about it. He covers an impressive range of topics, starting with the goal of adding a generator, battery, charging system, lights, and accessories to the bike. From there he clicks off one thing at a time, researching and ordering a wheel with a Dynamo hub for the generator, assembling and testing the cells of his battery, choosing the controller board for the charging system, and designing the accessory circuits like the iPhone charger above. If he adds too much more to the two-wheeled rig he’s going to have to plan a big road trip with it.

[Thanks Xuxo]

Reverse Engineering Apple’s Recharging Scheme

[vimeo=http://vimeo.com/13835359]

[Ladyada] has been hard at work reverse engineering the charging method used by Apple products. This saga takes us through the years as new devices were released and subsequently broke Minty Boost’s charging capabilities. It seems the data lines were gradually adopted as a means for iPhones and iPods to identify the charger that had been connected. By adding voltage dividers to the D+ and D- lines you can instruct the handheld to pull 1 Amp (with data voltages of 2.8v and 2.0v) for wall chargers or 0.5 Amps (2.0v on both data lines) for portable chargers. In the video above [Ladyada] removes the surface mount resistors from a commercial charger in order to measure the voltage divider and discover the secret.

Update: Custom Cellphone Induction Charging

This is a custom back plate with induction charging circuitry that [Derek Hughes] build for his HTC HD2 cellphone. When we checked in with him last week he showed us how to add an inductive charger without voiding the warranty but it wasn’t very pretty because the stock back plate blocked the inductive field and couldn’t be used. The solution he came up with will work with any device if you want to put some time into the build.

He took two different aftermarket cases; one fits his cellphone and the other is a BlackBerry case meant for housing a credit card. After cutting a hole in the back of the cellphone case he epoxied the credit card holder in place, smoothed the seam with Bondo, and repainted. Not only does the charger fit in the credit card case, but there’s still room for a credit card. [Derek] also measured the magnetic fields around the circuitry and found they will not damage the magnetic strip on that American Express Black you’ve been keeping on you. In the video after the break he mentions the last step in finishing this case will be to locate a 90-degree USB plug as the current connector is a bit of an eyesore.

[youtube=http://www.youtube.com/watch?v=DgNOqJBSKmQ]

A More Powerful Boost Charger

[Meseta] built a powerful boost charger to top off his portable devices. He was inspired by the Minty Boost but wanted to overcome the rather limited capacity provided by the two-celled product. He ended up building his own DC to DC boost circuit rather than using an all-in-one IC. As you can see, the result uses four 18650 lithium-ion cells, normally found in laptop batteries, and can power two USB devices at the same time.

60 Watt Solar Panel Built From Cells

Our love for solar projects continues on with this method to make your own solar panels. [Mike] built a 60 watt solar panel from individual solar cells he purchased off eBay. Procuring parts off of eBay normally causes others hardship when they try to duplicate the project, however in this case there are so many types of cells people can use to produce their own unique solar panel. Even cells that are extremely damaged my still be used, as in this example. To charge a 12 volt battery the number of cells in series just needs to be 16-18 volts, and the rest in parallel will supply more current. Charging a battery without a charge controller is not recommended, but commercial ones are easily had. Those not interested in jumping all the way in with solar may want to test the waters by building their own panel and putting it to use as a charging station for your portable gadgets.

USB Wall Charger


[rbhays] did this sweet little hack back in 2006. He took a Motorola cellphone wall charger and modified it into a USB wall charger. He needed to charge his iPod, but misplaced the original charger. A replacement would have cost him $30. So he did what any respectable hacker would do, he cut up something else to make it work for him.

He had one sitting around that was equipped with a mini USB end. He checked it out and it was the perfect voltage. Some commenters below the project noted that their motorola charger had a higher voltage rating than his. Those would still work, but would require some extra steps to bring the voltage down.

After some careful soldering, and a bit of super glue, he’s left with a perfectly good wall charger. He can charge most things that only use the juice from the wall. Some things refuse to charge though, such as Zunes. There was another project by [Cvesey] that claims to charge Zunes as well. While wall chargers may be available fairly cheaply now, many of us have some of these cellphone chargers just sitting around. Now we have a use for them.

New Sparkfun Designs


Sparkfun has recently released a bevy of new boards and other devices, with some very intriguing new builds among them.

The first board that caught our attention is the Wee. It is a compact Arduino compatible controller that features a small size, low voltage, and many other minimalist attributes. It is built around an ATMega 168V and uses all SMD parts.

For even tinier fun, check out the LilyPad LED. It is a LED designed to be incorporated into clothing, featuring large holes for threading, a thin and extremely small PCB and a very bright 250mcd light. It is also washable, meaning that one or many can permanently be incorporated into clothing without fear of losing them. You can see these in the turn signal jacket we covered earlier.

The last one we’ll discuss is the LiPoly Charger, a USB lithium ion battery charger. Based on the Max 1555 IC, the LiPoly can use USB bus power or a 2.1mm center positive wallwart power(it uses the more high-powered wall-wart if both are connected). It can’t charge NiMH batteries, but it is still compact, efficient, and very useful.