[Kenneth Finnegan] took the focus of a great design and redirected it to solve his own problem. What results is this lead acid battery charger based on the 555 timer. It’s not a top-of-the-line, all the bells and whistles type of charger. But it gets the job done with a readily available IC and no need to code for a microcontroller.
The original idea came from a solar battery charger entered in the 555 timer contest. The main difference in application between that and [Kenneth’s] application is the source. A solar array or wind turbine is limited on how much juice it can produce. But mains power can push a shocking (har-har) amount of current if you’re not paying attention. Herein lies the alterations to the circuit design. To control this he’s using a Laptop power supply as an intermediary and only implementing the constant current portion of the tradition 3-stage lead acid charging profile (those stages are explained in his write up).
He did a talk on the charger at his local radio club. You can see the 90-minute video after the break.
Continue reading “555-timer charges lead acid batteries”
This one’s a riot! [Nico] got a new computer and didn’t want to change the six power supply cords he had strategically placed around his home and at work. So he just added a second charging jack that accepts a different style connector.
First off the laptop is used — but it’s new to him. So cracking it open and soldering in a new jack doesn’t affect the already expired warranty. He had an unlimited supply of Dell laptop chargers available from work. They are rated 19.5V and the charger for this computer is rated 20V so he figured this should be no problem. Instead of just swapping out the old charging port he added a second where the RJ-11 connector (for a telephone modem) was located. Now he doesn’t need to waste money buying more chargers for the new-old machine.
This isn’t the first time we’ve seen someone replace a power jack. But it is the first computer we’ve seen that takes two different chargers.
Here’s [Mikey Sklar] posing on his new electric skateboard. Well, it’s new to him at any rate. He bought it used on eBay for $250. That may not sound like much of a deal, but these will run more like $800 retail. The savings comes because the thing would no longer charge. But it took him just an hour and a half with his capacitive charger to resurrect the flat lithium cells.
The first thing he did in trouble shooting the situation was to measure the voltage of the battery pack. It registered 5V, which is a far cry from the 36V it should supply. The built-in charger does nothing, as it’s circuitry isn’t designed to work in a situation like this one. But [Mikey] has a tool perfect for this purpose. Da Pimp is a capacitive charger which we’ve seen before. It succeeds where the other failed because it is able to adapt itself to the internal resistance of the battery, no matter what voltage level it starts at.
[Mikey] shows off the use of his charger in the clip after the break. His first test run was more than two miles without issue.
Continue reading “Open source capactive charger resurrects an electric skateboard”
The Raspberry Pi foundation is in a somewhat unique position. They always test the units that get returned to them in hopes that they can improve the design. They often request that the power supply also be sent back with the RPi unit, as we know the board will not work well if the PSU can’t source enough current. And so they’ve been able to get a look at several counterfeit iPhone chargers. This is not one of the recommended ways to power the RPi, but their ability to collect failed hardware means that they have identified three different fakes on the market.
Seen here is a genuine Apple product on the left. The others are fake, with the easiest way of spotting them being the shiny chrome plug connectors. The genuine part has a matte finish on the connectors. There is also a difference in the chamfering, and even a variation on the orientation of the USB port on some of them. Unfortunately we don’t get a look inside, which is what we really wanted. But you can see in the video after the break that weighing the adapter will also give it away as a fake, showing that the components within probably vary quite a bit. This reminds us of some other fake PSUs that have been exposed.
Continue reading “Raspberry Pi foundation looks at counterfeit Apple power supplies”
Drone technology is driving the aerospace industry as companies trip over each other trying to develop the next big thing. Here’s a good example of what we’re talking about. Lasers can no be used to keep a UAV in the air indefinitely. The trick is to add an array of photovoltaic cells specifically tuned to an IR laser’s wavelength. A ground system then directs a high-intensity laser beam onto the aircraft’s cell array to transfer energy while in flight.
After the break you can catch a video from a trade show where a Lockheed Martin employee describes the successful testing of such a system. But there’s a lot more information available in the white paper (PDF) which Laser Motive has released. They’re the folks behind the technology who have teamed up with LM to implement the system. The laser unit on the ground can track a UAV visually, but there is also a method of using GPS coordinates to do so in the case of overcast skies.
Continue reading “Laser power system keeps UAVs flying indefinitely”
This is a Gemei G9T, a 9.7″ Tablet running Android 4.0. [Carnivore] shows us how to modify it to use inductive charging. The inductive charging hardware is taken from a Palm device (this uses the Touchstone charging hardware seen in several other hacks). It’s easy to interface with the tablet’s electronics, but physically placing the coil and magnets is another story.
The video after the break gives you a full walk-through of the process. He starts by removing the screws and prying the case off of the tablet. From there [Carnivore] shows how to carefully remove the coil, circuit board, shielding, and magnets from a Palm back plate. The magnets are the first to be positioned on the tablet’s back plate. The metal is too thick for them to hold well so he uses a Dremel to grind away just enough material for a strong connection. Unfortunately the metal will shield the magnetic fields the coil needs to work so he cuts a hole in the case the same size as that coil. The area is covered in liquid electrical tape to prevent shorts, and everything is taped in place. Two jumper wires connected from the coil’s circuit board to the 5V charging input are all it takes to finish up the hack.
Continue reading “Adding inductive charging to an Android tablet”
That grey box at the top of the photo is a modular power supply unit for a rack-mounted server system. [Sebastian] decided to repurpose it as a charging source for his RC batteries. He chose this HP DPS-600PB because of its power rating, efficiency, and you can get them at a reasonable price.
This is an active power factor corrected (APFC) PSU, which he says draws 40% less current than the non-APFC variety. Since he sometimes charges batteries in the field from a generator this is a big plus. But a bit of modification is necessary before it can be used as a source.
Since this is a rack device it has a set of connectors on the back. For power there are spade connectors which mate with a fin on the rack. He soldered positive and negative leads between the spades to interface with the battery chargers. The PSU won’t fire up if it’s not in the rack, so some jumper wires also need to be added connecting three of the interface pins.
With his modding all worked out he went on to use two PSUs for a 24V source, housing them to a nice carrying case while at it.