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Robert Dunn holds a button in his hand for controlling a spot welder

Raise you’re hand if you’ve ever soldered directly to a battery even though you know better. We’ve all been there. Sometimes we get away with it when we have a small pack and don’t care about longevity. But when [Robert Dunn] needed to build a battery pack out of about 120 Lithium Ion cells, he knew that he had to do it The Right Way and use a battery spot welder. Of course, buying one is too simple for a hacker like [Robert]. And so it was that he decided to Build a Spot Welder from an old Microwave Oven and way too much mahogany, which you can view below the break.

A Battery Cell with a spot welding tab attached
Spot Welding leaves two familiar divots in the attached tab, which can be soldered or welded as need.

For the unfamiliar, a battery spot welder is the magical device that attaches tabs to rechargeable batteries. You’ll notice that all battery packs with cylindrical cells have a tab with two small dimples. These dimples are where high amperage electricity quickly heats the battery terminal and the tab until they’re red hot, welding them together. The operation is done and over in less than a second, well before any heat damage can be done. The tab can then be soldered to or spot welded to another cell.

One of the most critical parts of spot welding batteries is timing. While [Robert Dunn] admits that a 555 timer or even just a manual switch and relay could have done the job, he opted for an Arduino Uno with a 4 character 7 segment LED display that shows the welding time in milliseconds. A 3d printed trigger and welder handle wrap up the hardware nicely.

The build is topped off by a custom mahogany enclosure that is quite a bit overdone. But if one has the wood, the time, the tools and skills (and a YouTube channel perhaps?) there’s no reason not to put in the extra effort! [Robert]’s resulting build is almost too nice, but it’ll certainly get the job done.

Of course, spot welders are almost standard fare here at Hackaday, and we’ve covered The Good, The Bad, and The Solar. Do you have a battery welder project that deserves a spot in Hackaday’s rotation? By all means, send it over to the Tip Line!

[Bob’s] Pac-Man clock is sure to appeal to the retro geek inside of us all. With a tiny display for the time, it’s clear that this project is more about the art piece than it is about keeping the time. Pac-Man periodically opens and closes his mouth at random intervals. The EL wire adds a nice glowing touch as well.

The project runs off of a Teensy 2.0. It’s a small and inexpensive microcontroller that’s compatible with Arduino. The Teensy uses an external real-time clock module to keep accurate time. It also connects to a seven segment display board via Serial. This kept the wiring simple and made the display easy to mount. The last major component is the servo. It’s just a standard servo, mounted to a customized 3D printed mounting bracket. When the servo rotates in one direction the mouth opens, and visa versa. The frame is also outlined with blue EL wire, giving that classic Pac-Man look a little something extra.

The physical clock itself is made almost entirely from wood. [Bob] is clearly a skilled wood worker as evidenced in the build video below. The Pac-Man and ghosts are all cut on a scroll saw, although [Bob] mentions that he would have 3D printed them if his printer was large enough. Many of the components are hot glued together. The electronics are also hot glued in place. This is often a convenient mounting solution because it’s relatively strong but only semi-permanent.

[Bob] mentions that he can’t have the EL wire and the servo running at the same time. If he tries this, the Teensy ends up “running haywire” after a few minutes. He’s looking for suggestions, so if you have one be sure to leave a comment.


Filed under: Arduino Hacks, clock hacks
Nov
21

Beautiful Touch-Sensitive Furniture

arduino hacks, capsense, Furniture, nightstand, wood working Commenti disabilitati su Beautiful Touch-Sensitive Furniture 

lamp

It’s taken over a year, but [tinkering techie] has finally completed his touch sensitive nightstand. At first glance, it looks like any normal piece of furniture. With the addition of an Arduino, some copper clad board, and a few LEDs, he’s turned it into a very elegant, electronic home furnishing.

The nightstand is built out of a few very nice pieces of mahogany. Underneath the top of the nightstand, three Kapton-covered copper clad boards are inset along the front and side edges. These capacitive sensing boards are connected to an Arduino Fio that reads the capacitance of these sensors and turns on a small LED under the drawer or the mains powered lamp.

The electronics are powered by a small USB charger with a battery backup all hidden underneath the top of the nightstand. Inside the drawer, a magnetic reed switch turns on an RGB LED whenever the drawer is opened.

While the nightstand itself is a wonderful piece of woodworking, we need to tip our hat for a remarkably seamless integration of fine furniture and electronics. The electronic furniture modifications we usually see are Ikea cruft, but this wonderful homemade nightstand should last decades or centuries.

Video of [techie] going over his build below


Filed under: Arduino Hacks


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