A capacitive discharge welder/cutter for all your lightweight needs


[Radu Motisan] wrote in to share a cool project he has been working on lately, a pulsed microspot welder/cutter.

The device is capable of spot welding thin metals such as foils and battery tabs by sending a pair of high current pulses between the two electrodes whenever [Radu] presses the trigger button. The cutting portion of his device uses the same general mechanism, though it requires a far greater number of pulses to get the work done.

The welding/cutting process is controlled by an ATMega16, which is also tasked with taking input from the user and displaying information on the LCD panel. The microcontroller creates quick (in the ten to several hundred microsecond range) pulses for both welding and cutting, with the latter obviously requiring a long series of pulses.

[Radu] started out using a relatively small capacitor array to power the device, but has recently upgraded to a 1.6 Farad car audio capacitor, which works (and looks) much better than before. His blog seems to update every few days with more pictures and details about his welding station, so be sure to check back often for updates.

Be sure to stick around to see a short video of [Radu] adding metal tabs to batteries and tearing down an aluminum can with his cutter.

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Improving your welder without a microcontroller

We’re always impressed when a piece of hardware is torn apart, rebuilt and ends up exceeding the capabilities of the original device. [Dave] and [Will]’s home-built TIG welder is no exception to that rule.

When [Dave] and [Will] started working on converting a simple AC stick welder to a welder with every function imaginable, they decided to keep it simple. After looking at some high-price commercial welders they came up with a list of features they wanted to have and decided to implement this in TTL and CMOS logic. The guys didn’t want to go with a microcontroller solution because not everyone can code, and discrete chips are very easy to troubleshoot given minimal tools.

For the high voltage part of the build, the original flyback transformer was replaced with a neon sign transformer and homebrew spark gap and capacitor. The plans for a homebrew spark gap and cap didn’t quite work out so they were replaced with commercial units. The guys included schematics and a PCB layout (PDF warning) of their build. It’s always great to see an amazing logic chip build, and improving an existing tool never hurts.

Thanks to [Franci] for sending this one in.

1000W search light – now build a bat signal

Forget flashlights, and leave those burning lasers at home, [Ben Krasnow] built a search light using a 1000W xenon arc lamp. That box you see on the side of the trash-can housing countains a starting circuit that shoots 30 kilovolts through the xenon lamp to get it started but it is separate from the power supply. [Ben] started experimenting with the lamp back in April but recently finished the project by using the inverter from an arc welder to get the 50 amps at 20 volts needed when the lamp is on.

The insert on the left of the image above is an outdoor picture of the beam. You can make out a tree at the bottom. Take a look at the video after the break for a full walk-through of the circuitry and some test footage of the finished product.

Continue reading “1000W search light – now build a bat signal”

LED goggles make you trip out?

Who knows if this works and should you really want to try to induce hallucinations by flashing colors in front of your eyes? But we do love the zaniness of the project. [Everett’s] homemade hallucination goggles come in two flavors, the small swimming-goggle-type model and the heavy-duty trip visor made from welder’s goggles. Each brings together the same components; a half ping-pong ball for each eye to diffuse the light from an RGB LED. The system is controlled by an Arduino with some buttons and 7-segment displays for a user interface. Put this together with some homemade EL wire and you’re ready for Burning Man.
[Thanks Evan]

Flux-cored to MIG welder conversion

[Rob] sent us some information on how he converted his flux-cored welder to a metal inert gas welder. He used a piece of DOM tubing as a collet with a side inlet tube that he uses to inject carbon dioxide. The gas is sourced from a 12 ounce paint ball CO2 tank and it looks like there’s a valve right at the junction with the collet. We wonder how long it would take to tear through one of those tanks, but if you’re not doing a lot of MIG welding this saves on the upfront cost of buying a separate setup.

DIY Lincoln welder conversion

[Fritz] built this 600 joule capacitive discharge spot welder in a case scavenged from a Lincoln plasma cutter. All of the circuitry was designed by [Fritz] and the schematics are available on his website. He has a few other welding related project also documented on his site that are worth checking out. While this isn’t the first homemade spot welder we have seen, it is definitely the first one with a case mod. If you are not up to the challenge of building one quite as complex as [Fritz]’s example, a microwave can be used as the donor appliance in simpler designs.

Capacitive discharge spot welder update


It seems one of our commenters took great umbrage with [PodeCoet] not documenting his capacitive discharge cutting properly. [PodeCoet] had been waiting till he got the full spot welder working before publishing, but he’s expedited the work after all our whining. Check out his full writeup of the device in its current state. It uses a 1Farad audio cap for storage. A dsPIC monitors all of the voltage sources and regulates charging. A nice touch is the tactile switch on the electrode.