How-to: Build Your Own Spot Welder

Spot welders are used in the fabrication of automobiles, PC cases, power supplies, microwave ovens, electrical junction boxes, Faraday cages, and various electronics. A spot welder is used because it produces a highly defined point of contact weld. The materials are welded without excessive heating, so working pieces are handled easily. The weld is also highly controlled and repeatable. In this how-to we cover the basics of a spot welder, and then show you how to build one from a microwave oven transformer.

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Induction Furnace

induction furnace

[Tim Williams] made his own induction furnace. A copper tubing coil forms the primary winding, as the material to be heated becomes the short circuited secondary. The load material is subject to high power magnetic fields operating at radio frequency. The rapidly changing field induces current flow within the material, creating a great deal of heat. The brute power required a cooling system to match. In the video below, the induction furnace can be seen melting common table salt.

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Adafruit Introduces The Sensor Pack 900

adafruit

Our friends over [adafruit] recently released the Sensor Pack 900, a collection of parts for anyone who is interested in using analog sensors with their projects. The pack includes 9 sensors. They range from simple thermistors and hall effect sensors to sharp distance sensors. Also included in the pack are 3 unidentified components that can be used to interface with the analog sensors in the pack. At only $30, the Sensor Pack 900 seems to offer a great set of introductory components for anyone prototyping a new device.

Repair A Malfunctioning LCD

When most people encounter dead pixels on an LCD text display, they figure that the display is dead and they decide to scrap it. However when the LCD display on one of [Joe]’s cordless phones started to show dead rows and columns of pixels, [Joe] decided that he could fix it. With only a pencil eraser, a hot air gun, and a screwdriver (for disassembly), [Joe] was able to fix his phone’s screen in just under 10 minutes. His process involves heating the glue holding the LCD’s ribbon cable to the phones PCB with a hot air gun and using a pencil eraser to reattach segments of the ribbon cable to the PCB. If anyone here has a problem similar to [Joe]’s, be sure to check out his detailed how-to complete with step-by-step pictures.

Bolt-action Coil Gun

bolt_action_coil_gun

TechEBlog has posted a few pictures of a student constructed coil gun. It’s bolt-action and includes a six round magazine. The gun only has a single stage to accelerate the projectile. While not as impressive as the portable coil pistol, it’s still more fun than most shop projects we’ve seen. You can find a video of the device below.

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Meat Thermometer Using Predictive Filtering

meatthermoafteradjustment

The guys over at NerdKits put together a really informative video on a meat thermometer using predictive filtering which is viewable below. The video, supplemental text, and code is available on their website. The thermometer is constructed of a LM34 temperature sensor attached to a piece of 12 gauge solid copper wire. The thermometer signal is processed on an ATmega168 microcontroller and visualized using the pygame library for python. The real gem in this project is their excellent explanation of predictive filtering, which could easily be utilized for a large number of projects.

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