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More Changes to Video Hardware

Posted by Tom Benedict on 02/02/2013

I recently returned to working on another non-KAP photography project that requires using a DSLR with a wireless video link. And though there are a number of differences between this and my KAP rig, there are some similarities as well. One idea that dropped out of the process was that there’s no reason I shouldn’t be able to use any of my cameras with my KAP video hardware. After all, the video hardware for this other project came with a bunch of cables that’ll plug into a range of cameras. Why not do the same for my KAP rig?

To date I have three cameras I’m actively using for KAP: my venerable Canon Powershot A650IS running CHDK, my Canon EOS T2i, and my new Gopro Hero3 Silver. As of last night, only the T2i had a video cable built for it. And as of last night there was no provision for making new ones. The T2i cable wired directly into the video transmitter.

A quick search on video cables for these cameras brought up some cool options. The Hero3 has a firm following among the RC airplane and helicopter FPV crowd. Since weight and space is a premium on board an RC aircraft, the cables available for the Hero3 are some of the lightest around. This one from FPV Hobby is one of the nicest I’ve seen. It’s a right-angle USB connector with a short length of three-conductor cable, terminating in two (two?) servo-style connectors. Hey! I’ve got plenty of servo connectors! What a great idea!

I used the same color code convention as the Hero3 cable from FPV Hobby: Black = Ground; Red = Audio; White = Video. Unlike the FPV Hobby cable, though, I put all mine on a single connector. In short order I’d cut my T2i cable, crimped in a pair of connectors to plug it back together, and then made a second cable for my A650IS. Voila! Interchangeable video cables!

Video Cables

While I was doing the work on the cables, I decided it was time to permanently mount the video transmitter on my rig. There are lots of options for packaging electronics on a KAP rig: real enclosures, Altoids tins, or just attaching the thing to the rig with Velcro. I went with another option on the video transmitter. It was already wrapped in clear heat shrink, and had an RP-SMA antenna connector on one end. SMA connectors require a 1/4″ hole for panel mount connections. Adding the appropriate hole to the Brooxes hardware on my KAP rig was a simple matter of marking and drilling the hole. Once the transmitter was in place, a lock washer and SMA retaining nut finished the job.

Video Transmitter Mounted

In an earlier post I mentioned I’d gutted my video power system in favor of dedicated LiPo batteries. This also appears to have worked out pretty well. The transmitter and receiver are both powered by a pair of 500mAh 3S batteries. I have no idea what the run time will be in the field. There’s a fair bit of testing to be done before I have a good figure for that. Meanwhile I’m using a pair of battery monitors similar to the ones I use on my plane to make sure I don’t drain them too far.

This has made the video receiver a nice neat little package on my RC transmitter. The monitor bolts onto a monitor arm that in turn is bolted onto the transmitter. The battery and video receiver are both attached to the back of the monitor. I got tired of the heavy wiring that came with the monitor and video receiver, so I wound up hard-wiring everything with a minimum use of connectors.

Video Receiver and Monitor

I’m almost 100% happy with where this KAP rig is now. There’s only one thing left to do: I’d either like to replace the 4xAAA battery pack that powers my rig with a second 2S LiPo, or I’d like to get rid of it altogether by using a UBEC to draw power from the video battery and supply the rig with 5V power. Using a second LiPo has a lot of appeal since it would let me continue to use the rig even after the video battery was drained. But the shutter cables I use can’t be powered with more than 6V or they blow. I’d have to wire a voltage regulator in line with the shutter cables or risk (no… guarantee!) frying them. For obvious reasons I’m leaning toward the UBEC.

It’s funny to look back and see how many iterations I’ve gone through with this KAP rig. It’s the same one I started with in 2007 with a Nikon Coolpix and a 72MHz radio. Since then I’ve changed cameras more than once, added and removed a third axis for plan rotation, added and removed video hardware more than once, and replaced more leg brackets than I can count. I even crashed it once. Hard. But it bent right back into shape. You just can’t beat it.

– Tom

4 Responses to “More Changes to Video Hardware”

  1. Ramon said

    I’m reading this stuff with an almost permanent big grin on my face. Why? This is all so reckognizable. But I am too lazy to blog it all like you do, Tom. Keep them stories and ‘braindumps’ coming.

    Pal PE1OUW

    P.S. How long would it take Tristan from Kiwi land to get his callsign…?

    • Tom Benedict said

      Hahahaha! Glad it’s fun to read, even if it is old hat.

      Ooooh… I bet if we worked on him, he could do it in a month of lunch hour study sessions. That’s about how long it took me to plow through the first book. (I actually made it through the second, and probably should have tested right then and there. But now I need to go through it again before I can talk on HF. Bleah!)


  2. Ramon said

    Plans are still vivid to have a kite lofting a camera AND a longwire antenna at the same time. Intention is to cross the North Sea and have a chat with Bill Blake and his KAP assistant/kite flyer/HAM Clive. Not sure I we can ever cross the oceans to have an NL-Hawaii link thru the airwaves. But wouldn’t that be nice…. If only….

    • Tom Benedict said

      It may be a while, for me. I’d still like to get my general license, but it’ll be a while before I can afford an HF rig.

      Ah! Either that or I need to learn Morse and get a much less expensive QRP radio!

      But in either case I’m not sure I’d be able to do KAP at the same time you are while talking over the airwaves. The talking part is fine, but if it’s day there it’s night here. Hmmmm… Ok, I need to make that stabilized rig first so I can do night KAP while talking on the airwaves! (See? Motivation!)

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