Need help with audio trigger for camera....how do I generate a beep/click 300m away?

Hey guys,

I have a DSLR Canon 550D camera with Magic Lantern modified firmware installed on it. This firmware allows the camera to be triggered by sound, utilizing the cameras onboard mic. The level of sound required to trigger the camera can be adjusted.
What I would like to do is have the ability to trigger the camera from quite a distance with some sort of audio trigger. If I have this trigger close enough to the mic and adjust the levels it would only need to make a decent click. To get decent range I am assuming I will need to use a radio device? Can anyone think of anything cheap and compact that could work as a trigger? Using walkie talkies is the obvious thing that comes to mind but these are rather bulky....ideally the trigger would be small enough to clip/tape to the camera. In terms of range, 200-300m would likely be the upper limit.

Any thoughts would be appreciated :)

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tig5 (author) 4 years ago
Ok so I have all the bits you suggested, thought i'd check a couple of things before i blow anything up.

The receiver board has 8 different terminals for connecting wires, split into 2 groups. Group 1 is a pair of terminals marked +12v and GND. I'm assuming this is my 12v battery input, am I correct in also assuming that +12v is where I connect my + battery lead and GND is where I connect my - battery lead?
Group 2 consists of 6 terminals marked C, N, O, C, N, O. I'm assuming these are the terminals that control stuff but I'm not too sure what to do with them.
I have my stripped wires connected to my 1/8 stereo plug, do you think I plug one of these wires in C, one in N and see what happens?

My main goal is to be able to trigger my video with this unit, but out of curiosity would it also be possible to activate or trigger a photo to be taken while the film is running? I notice the "sender" has an A and B button which suggests I could use my receiver for 2 tasks but I guess that depends on how many tasks my camera can do via a stereo plug input. Anyway that's not vitally important but I just figured if there were other useful features I could utilize or activate from a distance now would probably be the right time to investigate them! Appreciate your thoughts.
aelias36 tig54 years ago
You're right with the battery connections. I'm pretty sure that N is common, O is normally open, and C is normally closed. Check this with a multimeter if you have one. When you press the button on the remote, N and O should have continuity.

If I was right about that, you'll need to connect the common wire of the cable to N, and the focus wire to O. If you press the button, the camera should act as if it's shutter button was focused.

If you want to also used the second relay for taking a photo, bridge the two N together with a small wire, and connect the shutter release wire (the remaining one) to the other O.
tig5 (author)  aelias364 years ago
I've managed to achieve what I originally wanted! I discovered that the stereo cable actually consists of 4 wires (i'm quite new to this), 2 inside each line. One line had an insulated white wire (1) with an uninsulated copper wire (2) wrapped around it and the second line had a red insulated wire (4) with another uninsulated copper wire (3) wrapped around it. I discovered that I could get the camera to focus by connecting 1 and 3, and i could get the camera to focus and take a photo by connecting 2 and 4, or by connecting 1 and 2. The only thing stopping me from having full control over recording and photographing is that if I use the trigger to take a photo I have to turn the camera on and off again before I can use it to trigger the record start/stop. I can record as much as I like but as soon as I trigger it to take a photo I lose the ability to trigger rec, the camera focuses but then nothing happens. I'm guessing this might be more a magic lantern bug than a hardware prob. I'm very happy with what I've acheived, thanks heaps for the help!
aelias36 tig54 years ago
Wow! That's great, and good for you! Glad I could help! There's a remote control Instructable contest by the way. Just saying. ;-)
aelias365 years ago
I have the T2i and magic lantern as well. :)

You can attach another microphone to the mic port on the camera. What exactly are you trying to do?
tig5 (author)  aelias364 years ago
Oops, posted instead of replying ^^^^
tig5 (author)  aelias364 years ago
Cool camera eh? A friend and I are going to ride scooters from Prudhoe Bay, Alaska to Tierra del Fuego. We plan on filming our trip without a cameraman. We would like the ability to do some "ridebys" where we set up the camera, trigger it to record remotely (hopefully with a small switch on the scoot's "dashboard") and ride past. There is also a product called SOLOSHOT we are looking at which will pan your camera to point and follow a moving object carrying a sensor. This product has a range of 500m. If we could trigger the camera from a similar distance we will have our "cameraman" issues sorted. I've thought of the cellphone idea, it's just a bit bulkier than I would like and it relies on having network coverage. A walkie would be ideal.......but still quite big
aelias36 tig54 years ago
Wow, this has been a while, huh? What about using this remote-controlled relay:


And connecting it to a shutter release?


This way, when you press the button, the shutter button will be pressed half way, and it will start recording. It has a range of 800m, which I'm sure is far enough.

It's not too hard to set up, either, especially if you have past knowledge in electronics. Cut the shutter release cable in half, and strip each of the 3 wires inside. When you connect two of them, the camera should start recording. Take those two wires and connect them to the terminal on the receiver board both marked "1." Just connect a small 12 volt battery to the terminals marked "-" and "+," and you're done! What do you think?
tig5 (author)  aelias364 years ago
That actually sounds great. So I could trigger photos and videos depending on my shooting mode?

Question: If I cut the shutter release cable in half.....strip 3 wires, connect 2 to the reciever board........do I leave the 3rd wire uncut? If I cut all 3 have I not just severed all connections with the camera? The shutter release cable looks like it has a 3.5mm mono plug which I assume feeds into the cam, I would want to leave that attached in some way.....
I can solder and have a basic knowledge of electronics. Thanks for your reply, instructables stopped notifying me of posts so it has been a while!
aelias36 tig54 years ago
I just realized you don't even need to buy a shutter release; you just need a 1/8" cable. It's stereo, by the way. The three wires are common, focus, and shutter release. You don't need the shutter release wire, because you only need to press the shutter button down half way to start recording.

Still buy the remote-controlled relay, but buy a 1/8" stereo cable to connect it to the camera.
tig5 (author)  aelias364 years ago
Ahhhh ok I see. I can also tell magic lantern to take a photo when i press the shuter halfway can't I? I've just ordered the relay so I'll let you know how I get along. Thanks again for the help.
aelias36 tig54 years ago
Bingo. It's under the "Movie" menu, labeled "Movie REC Key." You'll need to set it to "HalfShutter."
canucksgirl5 years ago
Could you use a spare cellphone at the camera and just call it when you need to trigger the sound? A cellphone's ring tone should be enough for this purpose and obviously has good range in most areas.