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.
Power outage? For the average citizen it’s very easy to take electricity for granted. Go a few hours or more without it though, and you’ll suddenly be reminded just what a luxury it is. During an emergency situation, sometimes you have to come up with alternative methods to get the job done. This human powered cell phone charger is a great example.
Using just a few ordinary around the house items, [The King of Random] turned a cordless electric drill into a human powered electrical generator. If the drill is run in reverse and cranked by hand, the generated energy can be transferred through the battery terminals to a connected device. So, he cut a USB charger cable in half and wired it up to the terminals to be able to charge his cell phone. Some yarn, a salad fork, a mixing beater, a scrap 2″x4″, some aluminum foil, and scotch tape were the only other materials he used. Using this technique, a totally dead phone battery was charged in around 3 hours.
Remember that this method is only intended to be used in an emergency, not as every day practice. Using these methods could potentially overheat or damage your gear, so be careful.
Check out the MacGyver worthy video tutorial after the break.
Continue reading “Human powered emergency cell phone charger”
Here’s a USB charging center which [Kenneth Finnegan] built using parts from his junk bin. We’d like to reiterate our claim that he must have the most magical of junk bins (the last thing we saw him pull out of it was a 24-port managed Ethernet switch).
The jack on the side accepts the barrel connector from a 12V wall wart. [Kenneth] mentions that the 2.1mm jack is a standard he uses in all of his projects. Inside there’s a switch mode power supply that provides the regulated 5V to each USB port. We really like the fact that he added some protection; diy is no fun if you end up frying your beloved multi-hundred dollar devices. The yellow components are polyfuses which will cut the power if 600 mA of current is exceeded. This works great for almost all of his devices, but his iPod 4G doesn’t like the system. It sees the voltage dip just a bit and stops charging entirely.
[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”