Wireless Mouse Li-Poly Retrofit With USB Charging

June 6, 2011 by Mike Nathan 22 Comments

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It’s no secret that wireless mice can eat through batteries pretty quickly. Rather than keep a fresh supply of AAs on hand at all times, [Phil] decided he would convert his mouse to use a rechargeable lithium polymer battery instead.

This isn’t the first time we’ve seen a cell phone battery crammed into a mouse to increase capacity, but we think this one has been done quite nicely. [Phil] managed to fit a 2.7 – 4.2v Li-Poly battery in the mouse’s palm rest, where there was a little extra empty space. The battery can be charged from any USB port via a custom-built charging module, which he constructed using a MAX1555 charge controller. Another custom-built circuit resides in the space previously occupied by the AA batteries, which uses an MC340063 DC to DC converter to drop the battery’s voltage down to the 1.25v required by the mouse.

The only part of the build that [Phil] is not pleased with is the power switch on the bottom, but since you rarely see that, we could care less. We think it is quite well done, and with a second version already in the works, we anticipate that it will get even better.

Be sure to check out [Phil’s] video tour of the hack, which you can see below.

Continue reading “Wireless Mouse Li-Poly Retrofit With USB Charging” →

Music Tank Puts The Boom In Boombox

May 27, 2011 by Mike Nathan 7 Comments

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When you think of Memorial Day weekend, what comes to mind? Well around here, all we can think about is this tank cum boombox that Instructable user [Elian_gonzalez] put together.

This build is actually the third version of his Music Tank, and it comes with all sorts of improvements over previous models. The tank is primarily constructed out of plywood, with cavernous compartments for holding all of its goodies. In its capacious body, the tank sports a 60 Watt stereo system that powers a pair of external speakers mounted on either side of the turret. The turret itself contains an air-powered cannon built from PVC tubing, which we imagine can be used to shoot a multitude of different projectiles.

While the concept itself is pretty cool, the tank happens to be nearly self-sustaining as well. The tank has a pretty deep battery well and uses a 50w home made solar panel to help keep things topped off while in use. [Elian] does not specify a total running time, but we imagine that it can go for hours on a nice, sunny day.

Keep reading to see a long video walkthrough of the Music Tank MK3 in action. Continue reading “Music Tank Puts The Boom In Boombox” →

Papercraft Flowers Teach Kids About Batteries

May 12, 2011 by Mike Nathan 6 Comments

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[Emily Daniels] has been teaching interactive electronics workshops geared towards children for some time now, recently holding a session that demonstrated how batteries work in a pretty novel fashion.

She wanted to keep things safe and simple due to the class size, so she didn’t want to rely on using soldering irons for the demonstration. Instead, she showed the children how batteries function by building simple voltaic cells with paper flowers, salt water, and LEDs. The paper flowers’ absorbency was used to act as a salt bridge between the wire pairs that adorned each petal. After salt water was applied to each of the flower’s petals, the center-mounted LED came to life, much to the amazement of her class.

The concept is quite simple, and the LED flowers are pretty easy to build, as you can see in her Instructables tutorial.

We think it’s a great way to demonstrate these sorts of simple concepts to kids, and hope to see more like it.

[via Adafruit blog]

Awesome Fan-powered Frankenscooter

May 5, 2011 by Mike Nathan 22 Comments

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We believe that some of the best things in life are built from half-assed ideas and held together with duct tape. Take this fan-powered Razor scooter [Charles Guan] built, for example – it’s chock full of both.

Having built a ducted fan-powered shopping cart in the past [Charles] is no stranger to ridiculous ideas. After a friend sent him a mockup of a fan powered scooter, he felt that he couldn’t “…take such an absurd image not seriously.”

Determined to make his fan-powered dreams a reality, he hunted around for Razor scooter parts, and managed to scavenge just about everything he needed. Parts of three scooters were welded together, forming the wide-stanced trike you see in the picture above. He mounted a fan and some battery packs onto the scooter, both similar to those found on his Fankart. Once everything was in place, he hit the streets.

As you can see in the video below, the Fanscooter looks as fun as it is loud. [Charles] says they have hit a top speed of about 10 mph thus far, but they should be able to blow past that once they balance the blades and have a ~~victim~~ tester willing to suspend his babymakers over the fan duct. Keep your eyes on his site, we’re sure to see some tweaks and improvements over the coming weeks.

Continue reading “Awesome Fan-powered Frankenscooter” →

Headphones Use Standard-sized But Proprietary Rechargeable Batteries

March 30, 2011 by Mike Szczys 83 Comments

Here’s something we haven’t run across before. We’re familiar with proprietary battery shapes (we’re looking at you, digital camera manufacturers), or custom recharge connections (look of death directed toward cellphone manufacturers), but using electrical tricks to force AAA brand loyalty is a new one. It seems that’s exactly what is happening with [OiD’s] wireless headphones which were manufactured by Phillips.

The headphones take AAA sized batteries and can use either disposable or rechargeable varieties. There is a warning label advising that only Phillips brand rechargeables should be used, and sure enough, if you try a different brand the performance suffers both in charging time and in battery life. The original batteries are labelled as Nickel Metal Hydride at 1.2V and 550 mAh, which falls within common specs. But [OiD] noticed that there is an extra conductor in the battery compartment that makes contact with the sides of the battery case. Further inspection reveals that a reverse-biased diode makes contact through this conductor with a portion of the battery which has not been painted. This is not true with other brands, allowing the circuit to distinguish between OEM and replacements.

[OiD] shorted out that connection and immediately saw a performance boost from his replacement batteries. It’s hard to know exactly what’s going on here without a full schematic for the circuit, but we’d love to hear your speculation on this setup in the comments. Is this a low tech version of the identity chips that camera batteries sometimes hide?

Wireless Electricity

August 28, 2009 by Mike Szczys 78 Comments

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[Eric Giler] has a talk available over at TED that discusses and demos delivering electricity without wires. Called WiTricity, these methods were developed by a team at MIT a few years ago who were working off of the concepts of Nicolai Tesla. The facts shared about our current energy delivery system are a bit shocking; we’ve spent over $1 trillion in infrastructure and produce more than 40 billion disposable batteries each year.

The demonstration in the video starts about 6:30 into it. At first we see a flat panel television powered wirelessly from about 6 feet away, then the T-Mobile G1 powered from the same distance. The thought of new TVs coming with WiFi and WiTricity standard would mean just hanging it on the wall with no cords to run. We can also image cellphones that have a battery only for backup purposes when you were not near a transmitter.

The power transfer occurs between two coils that resonate at the same frequency and only that frequency. This remind us a bit of Orson Scott Card’s fantasy communications device from the Ender’s Saga.

LED Battery Level Indicator

July 3, 2008 by Juan Aguilar 16 Comments

[Kc7fys] came up with a this simple battery level indicator. It uses a single LED to display a battery’s voltage; if the voltage exceeds 12V, it glows green. If it is below 11V, the LED glows red. Anything in between generates an orange glow. The meter is built around an LM358 chip per this schematic, but his actual build looks pretty sloppy because of the dead-bug assembly (check out NASA’s pretty version). Nonetheless, it works, so clean it up and build one if you want to put it (or your batteries) to the test.