A Pedal Powered Cinema

When the apocalypse hits and your power goes out, how are you going to keep yourself entertained? If you are lucky enough to be friends with [stopsendingmejunk], you can just hop on his pedal powered cinema and watch whatever movies you have stored on digital media.

This unit is built around an ordinary bicycle. A friction drive is used to generate the electricity via pedal power. In order to accomplish this, a custom steel stand was fabricated together in order to lift the rear wheel off the ground. A 24V 200W motor is used as the generator. [stopsendingmejunk] manufactured a custom spindle for the motor shaft. The spindle is made from a skateboard wheel. The motor is mounted in such a way that it can be lowered to rub the skateboard wheel against the bicycle wheel. This way when the rear bicycle wheel spins, it also rotates the motor. The motor can be lifted out of the way when cruising around if desired.

The power generated from the motor first runs through a regulator. This takes the variable voltage from the generator and smooths it out to a nice even power signal. This regulated power then charges two Goal Zero Sherpa 100 lithium batteries. The batteries allow for a buffer to allow the movie to continue playing while changing riders. The batteries then power the Optomo 750 projector as well as a set of speakers.

Movie night at the lake cabin

[Andrew’s] family has a rustic lake cabin. There is a lot to do during the day, but since there’s no electricity your options are limited when the sun goes down. Sure there’s the traditional campfire, but lately they’ve been spicing things up with an outdoor movie viewing.

To get this up and running they needed to build a projection screen. He’s going for a 2.35:1 aspect ration, but the technique will work for any aspect if you do your own math. They had a couple of extruded aluminum channels from an old chalk board which work perfectly as the top and bottom rails of the frame. With the width set at fourteen feet he just needed to mount the cross pieces on uprights at 5.95 feet apart. This provides a 183″ viewing surface.

White bed sheets serve as the screen material. After it’s stretched into place they line the rails with binder clips to hold it in place. The projector is powered from two 12V batteries via an 800W inverter. During the day the batteries get topped off by a solar panel system.

One minute review of your wasted time

It’s easy to throw around the accusation that you waste time throughout the day. Now you can prove it by reviewing everything you did on your computer, all in just one minute. [Dan Paluska] ground out some code to take screenshots and assemble them into a video.

His script ties together the open source tools FFmpeg, ImageMagick, and scrot. It takes a snap every 15 seconds in a 10 hour period for a total of 2400 frames. He even outlines the process to automatically upload these clips to YouTube. Just remember, if you’re doing something naughty, there’ll be a record of it.

Canon 40D hacked to record movies

Both Canon and Nikon recently released DSLR cameras that now include a feature that most consumer level digital cameras have had for sometime: the ability to record movies. What makes movie recording especially appealing on a DSLR is the wide selection of lenses available to get the look you’re after. If you’re an owner of Canon’s 40D you may want to follow [DataGhost]’s progress on the CHDK forum as he is currently working on bringing this function to the 40D.

While [DataGhost] has a working proof of concept he notes that there are still some issues pertaining to the camera powering down while recording a video, autofocusing, and writing to the memory card. Aside from this, [DataGhost] has made considerable progress and is considering adding custom user settings via the mode dial to really give some creative control. We’re excited about this hack and can’t wait for its release to the general public.

[via CHDK forum]

Magnetic Movie

Magnetic field lines may be invisible to the naked eye, but they behave in ways that would amaze us if only we could see them. [Ruth Jarman] and [Joe Gerhardt] from Semiconductor wanted to make them visible for everyone, so they produced Magnetic Movie, a film that combines animations, theoretical models, and actual VLF recordings of the entire Earth’s magetic forces to create a film that shows magnetic fields moving and jumping through the air in living color.

The film is part art project and part scientific experiment, but we can enjoy it on both levels, as watching the path and motion of magnetic field lines is both beautiful and informative. Get a glimpse for yourself after the break.

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