Monday, 8 December 2014

A sorely overdue update on The Window

So after I posted about my future plans of mounting a paintball gun to The Window, and making a refrence to the pan/tilt turret I had mounted on it, I realized that I never actually got around to posting that update. All of this was done way back near April sometime, but I never did anything with the pictures. Anyway, to the good stuff.

Before I get into the nitty gritties, here are a few shots of the whole thing from different angles:
As you can see, I added some landing gear to get it up off the ground in order to mount the gimbal below. The landing gear is made from some more 1/2" PVC and 4 1/2" to 3/4" tees that had half of the the T part cut away so they could be screwed to the edges. It was straightforward with two things to note, the dimond shape is due to sloppy work on my part not getting the landing gear tees all mounted at the same angle and thus needing different legnths of pipe to make it sit on all four legs, and the string running around the landing gear is due to the frame flexing a little without the support. When there was no string running around the perimiter, due to the angle, the legs would flex out, causing the 4 center arms to flex and be under stress when it was sitting on the ground and potentially breaking them on a hard landing. My solution was to run a string around all of the legs and so keep them from being able to bend outwards. The string itself is one strand from a DCCB 1800 YG Dacron rope used to Aero tow gliders. There was some short ends left over from making glider tow ropes and I snagged some, one strand from the rope is more than strong enough and has absolutely no stretch at all making it perfect for this.

Using my usual ultra high quality manufacturing methods of zip ties, hot glue, and this time a little aluminum, I cobbled this sucker together:
I originally thought that my ATC mini would output video as it recorded, but it turned out that the video out jack was just to be used for watching the footage afterwards, useless for what I wanted. So after struggling around for a little while and burning out at least one board-level camera I ended up with the ugly-as-all-get-out (whats new eh? It fits with the rest of the build) camera/solder/hot glue job you see there. I think the camera came out of one of those "Spy Gear" kid's toy remote controlled cars with a camera mounted on it that my friend disassembled. I soldered a piece of coax from an old RCA cable to the video out and ground and just used a single strand of hook up wire twisted around the outside for power. It is mounted to a piece of aluminum which also mounts the ATC mini and is connected to the tilt servo, bent so that the two cameras are both looking in the same direction. As for the servos, as you can see they are zip tied to each other and attached to a tee with half cut off of it and the center high point filed away for mounting on the octocopter. The tee is simply hose clamped to the frame for easy removal. In these pictures you can also see the video antenna which is the large PCB with a copper square on it. This brings me to this picture:
You can see in the upper middle of the picture a small proto circuit board, and mounted on it is the module from a 2.4GHz video sender. I purchased the video sender kit a long time ago and used it in various robots and such, and a little while ago I removed the module from it. Basically inside of video senders are small little boxes with pins sticking out that are the actual transmitter and are much much smaller than the whole unit. Mine was about an inch squared and like a quarter of an inch thick. The only snag is that it required a regulated 3.3v supply which I did not have on hand. So I ordered a tiny little module that had everything included and simply in and out leads. I soldered everything onto the proto board and added a few jacks for connections. That explains why the antenna is that plate directonal antenna, it was the stock one from the video sender. You can also see in the picture the RX for the pan/tilt gimbal, just a fairly standard 3 channel 27Mhz hobby set of which this is the TX:
That is about all there is to say about the octocopter itself, but I have one other acessory that I would like to talk about before I go. The idea was for me to fly the octo while someone else has the gimbal controller and a screen showing the video. Well in the intrest of portibility, I decided to make a DIY headset for the cameraperson:
Go ahead and laugh, I admit it looks totally stupid, but hey it works :) its reasonably straightforward, viewfinder hacked out of one of those huge old camcorders, hooked up to a circuit board to regulate the voltage to it and have some nice video connectors, 2 cell LIPO battery and the video reciever all strapped to a baseball cap. Yeah it looks totally stupid, but it was fun to build and it does indeed work. The trickiest part of the whole build was getting the viewfinder positioned correctly in front of the person's eye. I wanted a handsfree solution and this was the best I could come up with with what I had. I think that actually a cowboy hat would be ideal but this is all I had. I played around for a long time trying to get something that would mount on the cap, be reasonably comfortable, and have the viewfinder positioned reasonably well, and that is what ended up working best. Its just a piece of scrap aluminum screwed to the brim in such a way that the bottom is about in line with the top of ones eye, so the viewfinder is in line. There isn't much else to say about that I think.

All ready to fly:
Thats the last picture I promise :) Thats what it looked like with everything needed for a filming outing. The only problem was that the 2.4Ghz signal from my octocopter TX caused huge interference in the video signal back to the base station, making it almost impossible to see what you were filming. But the proof of concept worked decently, it just needed better equiptment. Anyway since then I have disasembled the video part of this thing, and I am working on my paintball gun mount as mentioned in the last window post.

So thats all for tonight, Happy Hacking!

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