Automatic capacitor charger lets you have fun with sparks

[GranTotem] is delighted by the sparks put out when a capacitor is rapidly discharged. But he’s not impressed at the relatively slow process of connecting them to a power supply for a recharge. So he built this auto-charging station for his capacitors that provides a shockingly good time almost continuously. Check out the video to see what we mean.

We always like to see the guts of the project, and that’s why we chose this image for the feature. But when everything is properly seated in the project box [GranTotem] has managed to achieve a really clean look. There are two barrel jack connectors on the end, one for 16V and the other for 20V inputs. The lid of the enclosure hosts an on/off switch, adjustment knob, and two banana connector terminals. Once switched on, a relay connects and disconnects the capacitor from the power supply at regular intervals which are adjusted by the knob. Just connect a couple of probes to those banana terminals and let the sparks reign down.

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Adjustable Tesla coil build

This coil has no trouble shooting sparks across four meters of empty air. [Finn Hammer] has been putting in some long hours on this labor of love, and we put in some time reading through his progress thread. He started down this path about a year ago and every step of the way he produces beautiful work. We enjoy seeing his prototyping techniques, moving from concept to hand drawing to CAD diagram before starting the physical build. Check out the demo video after the break and as you read through his thread look for the green arrows that lead to other videos and resources.

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Turn your old hard drive into a sander/grinder

[Jipa] over at MetkuMods put up an original re-use for old hard drives: make em into power tools. The tiny servo motor that drives the spindle doesn’t generate much torque, but once the drive is spinning fast enough, the inertial force of the platter is enough to make it usable for small grinding/sanding projects. The platters are re-stacked directly on top of each other to increase strength – we’d suggest a few dabs of epoxy to make em even stronger. Once stacked, a piece of sand paper is cut to size and held on by the center platter washer. [Via hacknmod]