[Julian] needed to weld a bit of nickel to some steel and decided to use a spot welding technique. Of course he didn’t have a spot welder sitting around. Since these are fairly simple machines so [Julian] set out to build a spot welder using a charged supercapacitor. The fundamentals all seem to be there — the supercap is a 100 Farad unit and with a charge of 2.6V, that works out to over 300 joules — yet it simply doesn’t work.
The problem is in how the discharge energy is being directed. Just using the capacitor would cause the charge to flow out as a spark when you got near the point to discharge. To combat this, [Julian] put a microswitch between the capacitor and the copper point he expected to use as the welding tip. The microswitch, of course, is probably not the best for carrying a large surge of current, so we suspect that may be part of why he didn’t get great results.
The other thing we noticed is that he used a single point and used the workpiece as a ground return. Most spot welders use two points near each other or on each side of the workpiece. The current from the capacitor is probably just absorbed by the relatively large piece of metal.
The second video below from [American Tech] shows a 500F capacitor doing spot welding with little more than two wires and it seems to work. Hackaday’s own [Sean Boyce] even made one out of some whopping 3000F caps. It did work, although he’s been pursuing improvements.
Continue reading “Fail Of The Week: Supercapacitor Spot Welder”
[Mike Harrison] is known for incredibly tiny soldering. Now he’s claiming a “world’s smallest” in the form of a stand-alone LED blinker, and we think he’s got the record.
He brought it along with him to Friday’s Beagleboard Bring-a-Hack, and we got a close look at the diminutive assembly. The project was dreamed up when [Mike] saw an announcement from Seiko about a new supercapacitor in a tiny package (likely the CPH3225A giving the blinky a footprint of 3.2 x 2.5 mm). With that in hand he added a PIC 10f322 microcontroller in a SOT23 package, an 0603 smoothing capacitor, and an SMD LED.
Blinky net to a metric ruler
US Quarter for scale (ruler is metric)
Charging jig doubles as a carrying case
With such a tiny package, the trickiest part is figuring out how to charge that supercap. [Mike] used a drill and hand files to make a square hole in a CR2032 battery holder to serve as a jig. The bottom of the supercap rests against the battery as a pogo pin makes the second connection to a terminal on the side of his assembly. It charges quickly and will happily blink away for about six minutes after charging.
Mike set out to make two of these, but dropped the second supercap when at his workbench to be forever lost in the detritus common to every electronics workshop. When he first pulled it out at the meetup we were on a rooftop terrace and we were more than a bit concerned that this would just blow away. How do you begin to fabricate such a tiny assembly? He used UV cured epoxy to glue them together first, then somehow completed the soldering by hand!
Continue reading “World’s Smallest LED Blinky”
If there’s one thing that brings hackers together, it’s the ability to build something for less money than it takes to buy it. It’s an exercise [Great Scott Gadgets] put to the test because he was playing around with some 18650 lithium cells, and had a huge need to put some tabs on batteries. This can be done by soldering, but to do it right you should really use a spot welder. Here’s the rub: you can buy a spot welder for about $250, and you can build one for a little less. So, the question: should [Great Scott] build or buy a spot welder? This wouldn’t be worth reading if he started off with an eBay order.
[Great Scott] designed this spot welder around a half-dozen supercaps, all securely held together with Kapton tape. This goes through a set of MOSFETs, and everything is controlled through an Arduino, a rotary encoder, and a dirt-cheap OLED display. It’s a simple enough circuit but a bit too much for perfboard, so [Great Scott] laid out a PCB and got a few boards for under $40. A bit of solder and some debugging later, and theoretically a spot welder was created.
After all that work, how did the spot welder work? Well, it didn’t. A slight misstep in the schematic meant this board didn’t have reference ground on the MOSFETs, so all this work was for naught. Of course, the only thing required to fix this board was a second board spin, as [Great Scott] probably bought more parts than necessary because that’s what smart people do. Still, he decided to cut his losses and shelve the project.
Continue reading “The Un-Economy Of Building Your Own Spot Welder”
[Mile]’s PTPM Energy Scavenger takes the scavenging idea seriously and is designed to gather not only solar power but also energy from temperature differentials, vibrations, and magnetic induction. The idea is to make wireless sensor nodes that can be self-powered and require minimal maintenance. There’s more to the idea than simply doing away with batteries; if the devices are rugged and don’t need maintenance, they can be installed in locations that would otherwise be impractical or awkward. [Mile] says that goal is to reduce the most costly part of any supply chain: human labor.
The prototype is working well with solar energy and supercapacitors for energy storage, but [Mile] sees potential in harvesting other sources, such as piezoelectric energy by mounting the units to active machinery. With a selectable output voltage, optional battery for longer-term storage, and a reference design complete with enclosure, the PPTM Energy Scavenger aims to provide a robust power solution for wireless sensor platforms.
Consider for a second the Internet of Things. A vast network of connected devices, programmable matter, and wearable electronics can only mean one thing: there’s going to be a ton of batteries. While changing the battery in a smoke detector may seem tolerable, changing the batteries in a thousand sensor nodes is untenable. The solution to this problem is self-contained sensor nodes, and right now the best power source for mobile devices is probably solar.
For his Hackaday Prize entry, [Shantam Raj] is building a self-contained sensor node. It’s a Bluetooth device for the Internet side of this Thing, but the real trick to this device is solar energy harvesting and low power capabilities through optimized firmware.
Basically, this system is a low-power SoC with Bluetooth. The power from this device comes from a small solar cell coupled with a very efficient power supply and some new, interesting supercapacitors from Murata. These supercaps are extremely small, have high storage capacity, low ESR, and fast charging and discharging. The test board (seen in the video below) provides a proof of concept, but this device has a problem: there’s a single ‘sanity check’/power LED on the board that consumes 4 mA. The microcontroller, when running the optimized firmware, only consumes 1 mA. Yes, the LED thrown into the prototype that only serves as an indication the device is on is the biggest power sink in the entire system.
This project is great, and it’s exactly what we’re looking for in The Hackaday Prize. If the Internet of Things ever happens as it was envisioned, we’re going to be buried under a mountain of coin cell lithium batteries. Some sort of energy harvesting scheme is the only way around this, and we’re happy to see someone is working on the problem.
Continue reading “Hackaday Prize Entry: Self Sustained Low Power Nodes”
Pity the lowly lead-acid battery. A century of use as the go-to method for storing enough electrons to spin the starter motor of a car engine has endeared it to few. Will newer technology supplant that heavy, toxic, and corrosive black box under your hood? If this supercapacitor boost box is any indication, then we’d say lead-acid’s days are numbered.
To be fair, we’ll bet that number is still pretty big. It takes a lot to displace a tried and true technology, especially for something as optimized as the lead-acid battery. But [lasersaber]’s build shows just how far capacitive storage has come from the days when supercaps were relegated to keeping your PC’s clock running. With six commercial 400F caps and a custom-built balance board, the bank takes a charge from a cheap 24V hand generator. The output is either to a heavy-duty lighter socket or some automotive-style lugs, and the whole thing is housed in a simple box partially constructed using energy stored in the bank. Can the supercaps start a car? Stay tuned after the break for the answer.
Although we’ve seen supercaps replace a motorcycle battery before, we’re a little disappointed that the caps used here only have a 1500-hour life – lead-acid wins that fight hands down. But this one gives us lots of ideas for future builds, and we’re heartened by the fact that the supercaps for this build ring up to less than $70.
Continue reading “Hand Cranked Generator Charges Supercaps, Starts Car”
Swedish scientists have created something they call power paper by using nanocellulose and a conductive polymer. The paper is highly conductive and has applications in supercapacitor technology and printed electronics.
The paper, technically called NFC-PEDOT paper, combines high conductivity and compatibility with conventional paper handling machines that could lead to less expensive manufacturing. The team used the material to create supercapacitors (up to 2F) as well as FET-like transistors known as OECTs (Organic Electrochemical Transistors).
Admittedly, the supercapacitor prototype didn’t look very practical (as they dunked it in a beaker full of potassium chloride). The black-colored paper is relatively conductive (42,000 S/m at 20 degrees C), at least for a paper. As a point of reference, silicon is about 1,000 S/m and iron conducts at about 10,000,000 S/m.
What can we do with NFC-PEDOT? Time will tell. We couldn’t help but wonder, however, if paper-based 3D printing couldn’t be adapted to use paper as an insulator or dielectric, foil as a conductor, and something like this material to build resistive elements. After all, we’ve seen something similar using foil and paper before.