Calling this a boom box is at least slightly ironic. Instead of high explosives it now carries high decibels in its new life as a self-contained sound system.
Despite the conspicuous power cord a peek inside reveals a big enough battery to keep the tunes playing for hours on end. [King Rootintootin] kept the cost on the build down since he was given the used speakers and amp by his girlfriend’s dad. The amp kicks out about 25 Watts with the battery rated at 7.2 Ah. He added a charger and routed the controls to the side of the ammo box so that it can be charged without removal. The only external component is the audio jack which connects it to the music source.
One of the suggested improvements from the Reddit thread is to add baffles inside of the enclosure so that sound from the two stereo channels doesn’t interfere with each other.
In the quest for the ultimate Android device, [白い熊] on the XDA developers forum created an awe-inspiring monstrosity that gives his Galaxy Note II 288 Gigs of storage and enough battery to theoretically last three and a half months.
First, the storage: the phone can now store movies, videos, apps, and music on an incredibly capacious 256 Gig SD card. Yes, this card currently sells for about $500, but having that much storage space effectively turns the Note into a portable hard drive running Android.
The battery comes direct from an eBay listing that advertises 8500 mAh inside a huge Li-ion battery. It’s extremely doubtful this battery will live up to the stated rating, but even if the new battery has twice the capacity as the stock battery [白い熊] is looking at about 10 weeks of standby time.
Yes, it’s just parts bought online and thrown together, but you really have to admire the sheer ostentatiousness of this phone.
[Ben Finio] designed this project as a way to get kids interested in learning about science and engineering. Is it bad that we just want to build one of our own? It’s a light following bristlebot which in itself is quite simple to build and understand. We think the platform has a lot of potential for leading to other things, like learning about microcontrollers and wireless modules to give it wireless control.
Right now it’s basically two bristlebots combined into one package. The screen capture seen above makes it hard to pick out the two toothbrush heads on either side of a battery pack. The chassis of the build is a blue mini-breadboard. The circuit that makes it follow light is the definition of simple. [Ben] uses two MOSFETs to control two vibration motors mounted on the rear corners of the chassis. The gate of each MOSFET is driven by a voltage divider which includes a photoresistor. When light on one is brighter than the other it causes the bot to turn towards to the brighter sensor. When viewing the project log above make sure to click on the tabs to see all of the available info.
This directional control seems quite good. We’ve also seen other versions which shift the weight of the bot to change direction.
Continue reading “Build a light following bristlebot as a way to teach science”
We find it frustrating when battery operated consumer electronics don’t include a way to connect an external power supply. We try not to purchase disposable alkaline cells if we can avoid it, and this dummy battery AC adapter hack will aid in our mission.
The battery compartment shown above is for a motorized baby swing. It accepts C sized batteries (who has those just lying around?) and lacks a barrel jack to connect a wall wart adapter. [Jason Smith] mentions you can get around this by connecting your positive and ground wires directly to the conductor springs. But using a dummy battery makes it a bit easier to remove the adapter if you do want to use battery power.
Each of the orange dummy is a wooden dowel with a screw at each end. The screws are connected with a piece of jumper wire, shorting the two terminals. This completes the circuit in the battery compartment and allows him to power everything from the adapter cell at the bottom. The adapter uses an LM317 adjustable voltage linear regulator. He used fixed resistor values to dial in his target voltage. The equipment should be rather forgiving as battery voltage starts higher than the printed value and drops as the cells are used up.
This technique has been around for a long time. One of our favorites was a hack that converted an Apple Magic Trackpad to USB power.
Continue reading “Dummy batteries let you use an AC adapter”
[Thomas] and his friends wanted to ring in the new year by setting off some fireworks. To keep a safe distance and have a little fun they built this network controller launcher (translated).
the image on the left shows the build in its unused and pristine state. But by the end of the celebration it look a bit melted and burnt. Still, for the first revision of the system it ended up working pretty well.
We’ve seen several remote fireworks launchers that burn up resistors to light the fuses. But this system is much more reusable. The image on the right shows the heating elements which light the fuses. Younger readers might have no idea what they’re looking at, but every automobile used to come with at least one of these electric cigarette lighters. Just drive 12V through them and they get burning hot relatively quickly. That’s where the car battery on the base comes into play. It is connected to the lighters using some mechanical relays.
In the food container attached to the side of the launcher you’ll find a Raspberry Pi which provides the web connection for the system. [Thomas] wrote code which uses a webpage with some bomb icons as buttons. Check out the video after the break to see him demonstrate how fast one of these lighters will glow red after pressing a button on his smart phone.
Continue reading “Network-controlled fireworks launcher”
This tiny little scratch-built electric tricycle is a insanely powerful. Some might think you don’t need a crash helmet for testing a trike, but seeing the video after the break where [Ben Katz] is flying through a parking garage while slaloming between the support beams proves that this ride has some pep to it.
Looking through the presentation post linked above is fun, but when we started digging though the six build log posts we felt ourselves getting sucked into the project. It’s a delight every step of the way. It started with an aluminum box which will host the two rear wheels, drive train, motor, and battery. [Ben] decided to go with A123 Lithium cells, and after testing to see how many he could fit in the space available he started making choices on the motor and driver circuit. When he finally got his hands on the actual cells for the project he took on the fascinating process of constructing his own battery. Dozens of them were hot glued, then soldered together before being encased by placing them in soda bottles and hitting the plastic with a heat gun. And we haven’t even gotten into the bicycle hub-gear transmission system, disc brakes, differential, chain-drive, and motor… you see what we mean about sucking you in.
Oh, and in case you’re wondering this is not [Ben’s] first electric vehicle build. Last year he was showing off his all terrain scooter.
Continue reading “Electric tricycle build log is like hacker crack”
We agree with [Zapmaker] that Canon cameras chew through nickel metal hydride batteries. But we’re not going to use Alkaline because we think it’s wasteful. His solution is to use a battery that has a higher voltage rating. What you see here is a single lithium iron phosphate cell paired with a dummy cell to increase life between charges.
The reason that NiMH batteries don’t last very long is that they’re only rated at 2.4V. It won’t take long for that voltage to drop below the camera’s cutoff threshold since they didn’t start very high to begin with. But a single LiFePO4 cell has the same form-factor but produces 3.2V and maintains voltage well through it’s discharge cycle.
The size is right, but using one cell won’t work by itself. He built a filler for the other slot which is just a wood dowel with a screw all the way through it. The point was ground down and a bit of foil added to ensure a proper connection. We’d be interested to hear back about how this performs over the long term.