Dirty Video Mixing With The Raspberry Pi Zero

Don’t get too excited now, we aren’t talking about that kind of dirty video. There’s plenty of other places on the Internet you can go to find that sort of thing. No, this video mixer is “dirty” because it combines two composite video streams into one garbled up mess that’s best viewed on an old CRT TV. Why, you may ask? Because rock and roll, that’s why.

Created by [Luke Blackford] as a visual for his band’s performances, the “Dirty Pi” is an exceptionally simple way to create some wild imagery with two Raspberry Pi Zeros. It might not be the most practical of devices, but if you want so throw some creepy looking video up on screens all over the house (say for an upcoming Halloween party), this is a fantastic way to do it on the cheap.

The idea is simple: connect the oft-forgotten composite video outputs of two Pi Zeros to a potentiometer, which then leads to the display. Play different videos on the Pis with the media player of your choice, and twiddle the potentiometer to create ghosting and interference. If you want to get that true 1980’s retro feel, put the whole thing into an old VHS cassette like [Luke] did, and you’re ready to rock.

Those who’ve been around the block a few times might recognize this trick as a variation of the [Karl Klomp] Dirty Video Mixer, and [Luke] tells us he likes this project because he was able to pull it off without writing any code or even doing any complex wiring, though he does imagine a future version where he adds some remote control functionality.

If you like your video mixers with more smarts and less dirt, we’ve covered a very slick build using the LM1881 in the past.

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Automated Doors For Theatre Effect

Door Actuator

For a theatre production, [Jason] needed a way to automatically open and close doors as a special effect. His solution, hosted on Github, lets him remotely control the doors, and put them into a ‘freak out’ mode for one scene in the play.

Two Victor 884 motor controllers are attached to an Arduino that controls the system. A custom controller lets [Jason] actuate the doors remotely, and LEDs are used to display the state of the system.

On the mechanical side, two wind shield wiper motors are used. These are connected to custom arms that were printed using a Lulzbot AO-100. The arms allow for the door to be automatically actuated, but also allow for actors to open the door manually.

The result is a neat special effect, and the 3D models that are included in the repository could be useful for other people looking to build automated doors. In the video after the break, [Jason] walks us through the system’s design and demonstrates it in action.

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Animatronics Reference

Anyone who is familiar with animatronics or even most robotics knows that almost every build is a hack if you don’t plan on reproducing it.  This gallery is to show off the work of [John Nolan]. However, instead of just posting the final product, he has posted several galleries that show, in detail, the internal structures. Curious how to rig a jaw or an eyebrow?  Wanna see the internals of an animatronic baby? How about building giant monster hands that are rugged and have full digit control? It’s all in the gallery.