Arduino Nano Runs Battery Spot Welder

Soldering might look like a tempting and cheap alternative when building or repairing a battery pack, but the heat of the iron could damage the cell, and the resulting connection won’t be as good as a weld. Fortunately, though, a decent spot welder isn’t that tough to build, as [KaeptnBalu] shows us with his Arduino-controlled battery spot welder.

spot_welder_zoomWhen it comes to delivering the high currents necessary for spot welding, the Arduino Nano is not necessarily the first thing that comes to mind. But the need for a precisely controlled welding pulse makes the microcontroller a natural for this build, as long as the current handling is outsourced. In [KaeptnBalu]’s build, he lets an array of beefy MOSFETs on a separate PCB handle the welding current. The high-current wiring is particularly interesting – heavy gauge stranded wire is split in half, formed into a U, tinned, and each leg gets soldered to the MOSFET board. Welding tips are simply solid copper wire, and the whole thing is powered by a car battery, or maybe two if the job needs extra amps. The video below shows the high-quality welds the rig can produce.

Spot welders are a favorite on Hackaday, and we’ve seen both simple and complicated builds. This build hits the sweet spot of complexity and functionality, and having one on hand would open up a lot of battery-hacking possibilities.

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Correcting Color Blindness With DLP Projectors

About five percent of the population is colorblind to one degree or another, and for them seeing the entire spectrum from Roy to Biv is simply impossible. Their eyes simply don’t have the cones to detect certain colors. The brain is the weirdest machine on the planet, though, and with the right tricks of light, even the colorblind can see more colors than they’re accustomed to. That’s the idea behind [PointyOintment]’s entry for the 2016 Hackaday Prize: color blindness correcting goggles.

Any device that claims to correct color blindness comes with a few caveats and a slightly loose interpretation of what ‘color blindness correcting’ actually is. For the same reason you can’t see deep infrared, someone with color blindness cannot distinguish between two colors; the eye simply doesn’t have the sensors to see a specific color of light. This doesn’t mean the ability to distinguish color in color blind individuals can’t be improved, though. The EnChroma glasses use an optical notch filter to block all colors between blue and green, and between green and red. This works, because the human brain is weird enough and can adapt to nearly anything.

[PointyOintmen] isn’t going with an optical notch filter. He’s using spinning color discs from a DLP projector and 3D ‘shutter’ glasses to present the world in different shades of color many times a second. It’s weird, untested, and will take a few hours to get used to, but it is a very interesting idea. Will it allow color blind people to see more colors? That’s a semantic issue, but if you define ‘seeing color’ as being able to differentiate between two different colors, yes, it will.

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Tombstone Brings New Life to Board

Making revisions to existing PCBs with surface mount components often leads to creative solutions, and this insertion of a switch over a tombstoned resistor is no exception. According to [kubatyszko], “this is an FPGA-based Amiga clone. R15 serves as joint-stereo mixing signal between channels to make it easier on headphone users (Amiga has 4 channels, 2 left and 2 right). Removing R15 makes the stereo 100% ‘original’ with fully independent channels. Didn’t want to make it permanent so I decided to put a switch.”

Whether [kubatyszko] intends it or not, this solution is not going to be permanent without some additional work to mechanically secure the switch. We’ve tried this sort of thing before and it sometimes results in the contact area of the resistor being ripped off the substrate and separated from the rest of the resistor, rendering it useless. However, the creative use of the pads to get some additional functionality out of the board deserves some kudos.

We love creative fixes for board problems but it’s been a really long time since we’ve seen several of them collected in one place. We’d love to hear your favorite tricks so let us know in the comments below.

Tiny Tea Timer for Your Perfect Cuppa

If you’re serious about your tea, you know that the line between a perfect brew and over-steeped dreck is a fine one. Seconds can make a difference, and for the tinkering tea drinker, this might lead you to build a tiny timer with just the features it needs to achieve tea perfection.

The circuit that tea-loving [acidbourbon] came up with for his timer is simplicity itself. It’s just an ATtiny25, an  LED, two pushbutton switches and a piezo buzzer on one side of the PCB, with a coin battery on the flip side. The battery holder is an interesting design – a couple of rows of pin headers and a bit of springy metal. The user interface is as simple as the circuit – the buttons increment the time either one or ten minutes. The timer starts right away, the LED heartbeat counts down the seconds, and a distinctly British tune announces when it’s time for tea.

One possible improvement might be to have the LED flash the number of minutes remaining rather than just a single pulse heartbeat. That would be good feedback that you entered the right time in the first place. Other than that, it’s small enough to be handy, does just one job, and does it well – sounds like good design to us. Of course, if you want to complicate it a bit, you could always automate the tea steeping process.

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What Happens When You Fold Paper a 7th Time?

Ever heard that myth(?) about not being able to fold a sheet of paper more than 7 times? Well if you’ve ever tried it you know it’s impossible to even fold it a sixth time with your bare hands… but what if you have an industrial hydraulic press to help you out?

News to us, a YouTube channel exists called the Hydraulic Press Channel, dedicated to — you guessed it — crushing absolutely anything and everything with the help of a hydraulic press. Narrated by a lovely old chap whose accent (and colorful language) we can’t quite place, the channel is filled with amusing videos of guaranteed destruction — including paper.

But the result is not what you would expect at all — you’ll have to watch the video to see. With a bang and a tremble the seventh fold seems to change the material properties of paper. Can anyone explain what’s going on here?

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Machine Shop Soaps Are Good, Clean Learning Fun

At first glance, it’s easy to dismiss the creation of custom bath soaps as far outside the usual Hackaday subject matter, and we fully expect a torrent of “not a hack” derision in the comments. But to be able to build something from nothing, a hacker needs to be able to learn something from nothing, and there is plenty to learn from this hack.

On the face of it, [Gord] is just making kitschy custom bath soaps for branding and promotion. Cool soaps, to be sure, and the drop or two of motor oil and cutting fluid added to each batch give them a little machine shop flair. [Gord] experimented with different dyes and additives over multiple batches to come up with a soap that looked like machined aluminum; it turns out, though, that adding actual aluminum to a mixture containing lye is not a good idea. Inadvertent chemical reactions excepted, [Gord]’s soaps and custom wrappers came out great.

So where’s the hack? In stepping way outside his comfort zone of machining and metalwork, [Gord] exposed himself to new materials, new techniques, and new failure modes. He taught himself the basics of mold making and casting, how to deal with ultra-soft materials, the chemistry of the soap-making process, working out packaging and labeling issues, and how to deal with the problems that come from scaling up from prototype to production. It may have been “just soap”, but hacks favor the prepared mind.

Telegram Your Devices

[Erhan] has been playing around with the Telegram instant messaging service. Initially, he worked out how to turn on and off LEDs from his cell phone: he sent commands from the phone through the Telegram bot API, to a computer that’s connected over serial to an MSP430 board that actually controlled the LEDs.

But that’s a little bit complicated. Better to cut out the middleman (err…microcontroller) and implement the Telegram reception and LED blinking on a Raspberry Pi. For a project that’s already using a Pi, using the instant messaging service’s resources is a very simple way to interface to a cellphone.

The code for both the standalone RPi project and the MSP430-based microcontroller application are available at [Erhan]’s GitHub. You’re going to be installing Node.js for their telegram-bot-api and jumping through the usual OAuth hoops to get your bot registered with Telegram. But once you’ve done that all on the Raspberry Pi (or target computer of your choice) it’s all just a few lines of fairly high-level code.

We’ve only seen one other Telegram application on and we’re wondering why. It looks pretty slick, and with the bot’s ability to send a custom “keyboard” to the phone along with the message, it could make cell-phone-based control interfaces a cinch. Anyone else using Telegram for bots?