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RC Servo Signal Decoder, Part 2

It works! I’ve continued poking away at this circuit to decode an RC airplane servo signal and trigger a camera shutter during flight, and I’m happy to report success!Once I switched to using the CD4013 flip-flop with a positive logic clear input instead of negative logic, it was a piece of cake. I have to say, living just a mile from one of the USA’s largest electronics dealers (Jameco) is pretty sweet. I can hit their web site and place an order for practically any obscure electronic component I can think of, then cruise down to their offices and pick it up from the will-call desk an hour later. Nice!I rebuilt the decoder circuit that I discussed last time, soldering everything together “dead bug” style. This was necessary in order to keep everything as small as possible, so I could fit it inside the camera body.  I forgot to take a photo before I closed everything up, but it looks very similar to this example from laureanno.com:When I first connected the servo, decoder, and camera, it didn’t work. Nothing happened when I toggled the switch on my RC transmitter. Setting up the oscilloscope again, I was able to see that the reference pulse width generated by the RC circuit I’d built was about twice as long as it should have been. I’m not sure how that happened, even with 20% tolerance components, but I was able to quickly swap in a different value resistor, and get it working perfectly. Then with a bit of creative packing, I managed to cram it all back inside the camera body.Today during my lunch hour, I was able to try it out for the first time. The shutter trigger worked fabulously! I wish I could say the same for the quality of the pictures, but unfortunately the focus wasn’t set quite right, and the photos are a little blurry. They’re still pretty fun to look at though. I was flying next to the headquarters of Oracle Corporation in Redwood City, California. Those are the clustered cylinder-shaped mirrored buildings you see in the photos. The plane looks like it was a little higher than the tallest building, which I think is 20 stories tall. See if you can find me in some of the photos!Click any of the thumbnails below to see the full-sized version.             February 27 Edit: I corrected the focus problem, and tried again. Unfortunately I got the propeller in some of the shots, and this new set wasn’t from as high an altitude. But I did get some great shots of the bay, an aerial self-portrait, and a flock of Canada geese.        

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2 Comments so far

  1. Jeff Hopkins February 26th, 2010 3:28 pm

    I assume you’re the guy standing in the parking lot next to the park… The photo quality is not really that bad, once you get them in focus it’ll be real nice.

    Glad to hear that it worked out!

  2. Steve February 27th, 2010 8:38 pm

    I posted a couple of new photos with the camera focus corrected. Better!

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