GOBO LED Projector Arduino RF Project
A little history. For a previous event we made a banner that was to be visible on the back wall of the stage. It had to light up and fade out according to the performers input on the tambourine with no latency, and stay on somewhat to remain visible when not activated. Aesthetically, I wanted the sign to disappear when it was off. We managed to do all this with the banner we made, but it was not perfect.
The sign was only good for this event, it was not scalable, it required hanging equipment, it wasn’t bright enough, it was time intensive to make and required a lot of raw materials. It was very portable for it’s size, but still bigger than I’d like to carry. The flexible materials to make it portable can also get damaged and distorted over time.
So, I sought out a different solution to the same issue. A GOBO projector! GOBO is an acronym that people aren’t sure exactly what it stands for, but “GOes Before Optics” is generally accepted. It’s basically a spotlight that lets you put a stencil in front of it. This specific one uses a very powerful SMD RGBA (red, green, blue, amber) LED. There is a spot for a tiny slide that can be easily replaced with any stencil like image. The projector is about the size of a 1 liter soda bottle and projects large, crisp, and bright images anywhere. It’s still vivid in a well lit room.
This device solves the issue of portability, versatility to show different images and cost effective to change images. It’s also very easy to install. It can clip to drop ceilings and it’s small enough to be mounted anywhere.
While the projector comes with an IR remote, it doesn’t give us the latency free response we want and also has range issues. Our goal is to get the device to work with the rest of our RF integrated devices.
To make the GOBO projector do exactly what I want it to do I need to create and add a system that will give me RF control over the projector. To get a better idea of how it works, I just started disassembling the projector.
I was very impressed with the build quality of the projector along with the fact that it had many connectors and harnesses inside. This meant I could add a harness with all my components instead of having to cut up all the wires on the projector. Due to projector’s nice modular design, I realized I could just make a plug-n-play kit that would allow me to revert the projector back to stock whenever I wanted to.
Proof of Concept (Breadboard prototype)
Before going straight to making the final product, I wanted to make sure my idea and the parts that I have would work. I setup everything loosely on a breadboard and made some connectors to clip into the projector. The RGBA SMD LED in the projector has a positive and negative cable for each color of the LED. I placed a TIP120 transistor for each LED color and coded an Arduino Pro Mini to cycle each color of the LED on and off using the transistors. That worked! Then I coded the Arduino to take signals from a ping pong paddles that would change the color of the projector according to the strength of the hit. Also a success!
Prototyping a Plug-n-Play Arduino RF controller for the GOBO projector
Now that I have a working proof of concept, I want to make a plug n play version that can be easily installed in the projector with out any soldering or rewiring of the projector itself which would allow you to reverse the projector back to the stock easily. The housing for the projector is small, but with some careful placement it can all find space within to maintain a clean, stock appearance.
Here’s the harness that shows the sections with the TIP12@ transistors and a section that feeds power to the Arduino from the projectors battery.
Now we carefully install it all and close it up while making sure not to snag on any wires or lenses.
Now to test it with our ping pong paddles.
It works!
Now we attempt to make our own quick slide with the 3D printer, (lasercutter is being serviced) . Not ideal but it works! it looks kind of cool and stylized.
This works too!
This is all for now, but here’s the next few steps I’m looking to improve on. I want to make better gobo slides on the laser cutter (not limited to stencil style designs). I want to make the harness fit into the projector easier. Since its still at the prototyping stage i would like the serial port on the arduino to be accessible so I may extend that to come to the outside of the housing. In addition it would be nice to make an interface to change base brightness and colors with a few buttons or knobs on the side of the projector. Maybe an invert option as well.
