Joule Thief Steals Power for a Clock

A common project among electronics tinkerers is the joule thief, a self-oscillating circuit that can “steal” the remaining energy in a battery after the voltage has dropped so low that most devices would stop working. Typically the circuit powers an LED until almost all of the energy is extracted from the battery, but [Lionel Sears] has created a specialized joule theif that uses the “extra” energy to power a clock.

The circuit uses four coils instead of the usual two to extract energy from the battery. The circuit charges a large capacitor which provides the higher current pulses needed to drive the clock’s mechanism. It can power the clock from a single AA battery, and will run until the voltage on the battery is only 0.5 volts.

Normally the clock would stop running well before the voltage drops this low, despite the fact that there’s still a little chemical energy left in the batteries. The circuit can drive the clock for an extended time with a new battery, or could use old “dead” batteries to run the clock for a brief time while the final little bit of energy is drawn from them. If you’re so inclined, you could even use hot and cold water with a joule thief to run your clock! Thanks to [Steven] for the tip.

Hackaday Links, September 14, 2014

Photonicinduction is back! The Brit famous for not setting his attic on fire has built a 20,000 Watt power supply. It connects directly to England’s national grid with huge connectors. Impeccable fabrication and triple servo controlled variacs, and apparently this will be used for making a lot of hydrogen and oxygen through electrolysis of water.

In case you missed it, there’s a group buy for Flir’s Lepton thermal imaging module. Here’s the breakout board.

Need to solder something away from an outlet, and all you have is a disposable lighter? There’s a fix for that.

A Raspberry Pi case designed to be compatible with Lego. Now we need a hat/shield for NXT connectors.

Need another channel in your RC remote? Here’s this. It uses the gyro gain channel on a receiver. If someone wants to figure out how this works, wee do have a rather cool project hosting site.

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Here’s something impossibly cool: The Macintosh PowerBop. It’s a Powerbook 170 with the floppy drive replaced with the radio in a cordless phone. It was part of France’s BiBop network, and you could buy private base stations for use at home. It is technically possible to use the radio as a wireless link to a modem, but [Pierre] couldn’t get PPP or a sufficiently ancient browser working. Plus ten points for taking it to an Apple store, and another twenty for trying to connect to our retro edition.

Chicken Lips. [Fran] and our very own [Bil Herd] are hanging out a bunch and recalling [Bil]’s time at Commodore. For this little featurette, [Bil] brought out his very own Commodore LCD. There are three of those in the world. Also included: tales of vertical integration, flipping bits with photons, and 80s era ERC.

Astronaut Or Astronot: Totally Giving Away A Power Supply

Hey! It’s time for another round of Astronaut or Astronot, where we try to give away a jumbo power supply to someone on hackaday.io if they have voted in the most recent community voting round.

Before I get around to telling you who won, we need to go over the criticism of the current voting scheme. There’s a lot of valid criticism out there about how the algorithm that presents projects to the voting page is broken. Yes, it weights projects so some are seen more often than others. And yes, it can be frustrating. However, the results of the voting have no bearing on The Hackaday Prize (the space thing), and the purpose of the entire community voting is to get people looking at the projects, give away t-shirts to the project creators and 3D printers, o-scopes, and power supplies to random people who have voted. We listened to your suggestions and we’re tweaking the algorithm that presents projects for the next round of voting. That starts Monday, we’re doing the drawing on Wednesday, and votes don’t carry over from round to round.

With that out of the way, it’s time to do the whole ‘pick a random person on hackaday.io and see if they voted’ thing. For this week’s lottery, I chose five random people on the site, hoping I wouldn’t go through all of them before giving away a nice bench power supply. The first person, [in3rtial], didn’t vote. You just lost out on a really cool prize there, man.

The second person randomly selected was [tyler]. He voted a total of six times this round. I voted fifty times, but we’re not picky. That means he wins a nice power supply. Everyone go congratulate him for living somewhere that’s cheap to ship a power supply to.

That’s it for this round of Astronaut or Astronot. We’ll have a new round of voting up on Monday. For a change of pace (and because we’re going to be at DEFCON at this time next week), we’re going to do the drawing on Wednesday nevermind, we’re totally doing the drawing from DEFCON. Oh, and if you haven’t, you might want to submit a project to The Hackaday Prize. There’s still time, and your odds of winning something are really, really good.

Overkill Phone Charger, Because, Well, Why Not?

ATX Phone Charger

There are times in a tinkerer’s existence where it is convenient to have the ability to plug in and power a lot of USB devices. Sure, you could use a USB hub but this may not be satisfactory if your devices require a lot of current. A computer may work but is not really a stand alone solution.

[Jeff] and the crew over at Make Lehigh Valley ran into this predicament. They were putting on an Adafruit Trinket class and needed a USB power supply to power all of the Trinkets that were going to be used. As any makerspace would do, they built their own USB Power Station, and the final product is certainly overkill for what they needed (that’s not a bad thing).

An old ATX computer power supply is a logical component to use for this type of project. These power supplies are usually available in abundance and will provide all the amperage any reasonable amount of 5v USB devices can ask for. The 5v output from the ATX power supply was wired to 8 USB jacks. Keeping up with the project’s resourcefulness, those USB jacks were scavenged from a couple of old PCI-slot USB hub panels. Not satisfied with only USB outputs, the guys also wired up some banana jacks so that 3.3, 5 and 12 volts were available for whatever project was being worked on. A 3D printed enclosure keeps everything neat and tidy.

This project used a bunch of recycled parts and solved a problem faced by the group. If you’re interested in using an ATX power supply to make a more bench-top style power supply then check out this build.

An AT-ATX: A Different Kind of Power Supply

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[Jedii72] needed a power supply. A quick search online revealed many instructions for building one out of an old ATX power supply, but — he didn’t want just any kind of power supply — he wanted to build an AT-ATX.

He started with a vintage AT-AT toy from the 80’s, and then began cutting it into pieces. Hold for gasps of disbelief. Don’t worry though — it was in poor condition to start with, so it was never really considered a collectible. After cleaning over 30 years of grime and dirt off the toy, he gave it a fresh coat of jet black paint — not exactly canon, but it does look pretty awesome. You know, it would make a pretty awesome Sci-Fi contest entry, don’t you agree? Continue reading “An AT-ATX: A Different Kind of Power Supply”

Bench Power Supply Constant Current EZ-SET

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Here is a nice hack you may find very useful if you have a cheaper bench power supply that supports constant current limit protection (CC mode) and the only way to set or check your max current limit is to disconnect your circuit, short the power supply outputs and then check or set your limit. Yes, what a pain! [Ian Johnson] was enduring this pain with a couple of Circuit Specialist bench power supplies and decided to do something about it. After finding a download of the circuit diagram for his CSI3003X-5 supply he was able to reverse engineer a hack that lets you press a new button and dial-in the max current setting. Your first guess is that he simply added a momentary button to short the power supply outputs, but you would be wrong. [Ian’s] solution does not require you to remove the load, plus the load can continue running while you set your current limit. He does this by switching the current display readout from using 0–3 volts off an output shunt resistor to using the 0-3 volts output from a digital potentiometer which is normally used to set the power supplies’ constant current limit anyway. So simple it’s baffling why the designers didn’t include this feature.

Granted this is a simple modification anybody can implement, however [Ian] still wasn’t happy. A comment by [Gerry Sweeney] set him on the path to eliminate the tedious multi-button pressing by implementing a 555 momentary signal to switch the circuit from current load readout to current set readout. This 2nd mod means you just start pressing your up-down CC set buttons and it momentarily switches over the display to read your chosen max current and a few moments later the display switches back to reading actual load current. Brilliant! Just like the expensive big boy toys.

[Ian] doesn’t stop with a simple one-off hack job either. He designed up a proper PCB with cabling and connectors, making an easy to install kit that’s almost a plug-in conversion kit for Circuit Specialist bench power supplies (CSI3003X-5, CSI3005X5, CSI3003X3, CSI3005XIII). It is not a 100% plug-in kit because you do have to solder 3 wires to existing circuit points for signal and ground, but the video covering that task seemed trivial.

This hack could very well work with many other power supplies on the market being Circuit Specialist is just rebadging these units. For now, only the models listed after the break are known to work with this hack. If you find others please list in the comments.

After the break we will link to all three progressive mod videos incase you want to learn how to mod your own power supply or you could just order a prebuilt kit from [Ian].

Continue reading “Bench Power Supply Constant Current EZ-SET”

Troubleshooting a Broken Power Supply

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How many power bricks have died on you? Have you ever tried to fix them? Sometimes it’s easier to grab another one (they grow on trees right?), but wouldn’t it be nice to save the broken ones from filling up landfills? Depending on the cause of death, it could be a super simple fix!

[Chaim-Leib] recently purchased a powered USB hub that came with a beefy 5v, 4A power supply — it worked great — until 6 months later, when it didn’t. The company sent him a new one, and let him keep the faulty one. Looking for a challenge, [Chaim-Leib] decided to crack it open and see if he could fix it himself.

No burnt caps, no fried diodes, no burn marks anywhere in fact! Luckily he spotted the culprit: One lonely resistor had lifted up from its pad. Having never jostled or dropped the power brick, this failure likely came from some kind of stress formed during original assembly — throw in a bunch of hot and cold thermal changes, and pop goes the solder pad!

It was a simple fix with some solder, and he emailed the company photos of his operation — they’ve promised to send them on to the engineering team to further evaluate the problem.

That was easy.