Dual Camera System?

[TravisKy]

Has anyone ever tried mounting two cameras on an aircraft? I am wanting one to point forward and one to point down. I think I would have a problem with interference from the transmitters. Any thoughts?

[poynting]

Switch between the cameras with an analog multiplexer, don't go to the trouble, extra weight, extra power, and likelihood of interference of using two separate transmitters. You'll need an analog mux that'll handle the bandwidth of the video signal, but that shouldn't be too hard. Of course, you'd also need a way to switch the video mux, but that'll probably just be driving a line low or high.

[TravisKy]

Can you recommend a video mux?

[Itzik Ronen]

Hi,
I did so with 2 systems (http://www.rcgroups.com/forums/member.php?u=51644 ). But you can do it with only one system. The idea is simple. I connect the nose camera and the main camera with RC switch that drives a relay. You have to connect all common wires together (it is better for noise reduction any way) and only switch the analog video wires. The nose camera is connected to the normally close leg of the relay, so in case of failure it will switch to the nose camera automatically.
Itzik

[sectrix]

Hey thats a great idea. I was going for a multiplexer myself. That idea is much simpler. The relay's coil doesn't make any EMI?

[kbosak]

Relay is good and I know it will work superb, confirmed, no interference, clean signal.
I bet 4xxx series MUX: maybe (guessing) 4053
Triple 2-channel analog mux/demux would be fit?

Some poor LCD tv from casio sometimes hang in split screen when you switch in the middle of screen sweep but this is unavoidable.
90% receivers and cameras have no problems.

[Itzik Ronen]

Hey thats a great idea. I was going for a multiplexer myself. That idea is much simpler. The relay's coil doesn't make any EMI?
No there is no any interference. But you have to fallow these 2 simple rules: Always when working with coils (inside the relay there is one) you have to connect a diode and capacitor in parallel to the coil. The diode is because of Lenz's law (pay attention to the polarity). The capacitor is to filter out any electric spikes. You will have a smooth switching. As I mention before, because there is no “grounding” in the airplane, connect all the negative points in the plane together, even or especially if you have several batteries. In my plane all the equipment is connected to the same “grounding” point and all the voltages point are related to that (ESC 14V; camera, VTx, OSD all 12V; BES, Rx 5V). Sorry for my English, did I clear myself? Helps?
Last tip: be sure that at “fail safe mode” the Rx switched to the nose camera.

[mlbco]

Years ago (1997) I flew remotely piloted aircraft with dual cameras (forward and down) and I would switch between them in-flight using a servo and a micro-switch from Radio Shack. If you keep the video input leads short there will be negligible noise on the line. The entire system weighs only a little more than the lightest servo you choose and is simple to build and operate, the servo pushes the switch lever to change cameras. You shouldn't need any more than this!

Steve

[Magician]

Years ago (1997) I flew remotely piloted aircraft with dual cameras (forward and down) and I would switch between them in-flight using a servo and a micro-switch from Radio Shack. If you keep the video input leads short there will be negligible noise on the line. The entire system weighs only a little more than the lightest servo you choose and is simple to build and operate, the servo pushes the switch lever to change cameras. You shouldn't need any more than this!

Steve

Steve,

Were you switching the video signal line or the power to the cameras? I assume this was the set up you used at the first MAV contests. Those were fun flights to watch.

Chris

[mlbco]

Chris,

I was switching the video feed only. I always kept both cameras powered up so the video was uninterrupted when switching.

Steve

[mlbco]

Here are 2 pictures of my ancient dual camera switch set-up. The servo has the micro switch mounted to it to switch the video feed going into the VTX, both cameras remain powered all the time. Check out the size of those 1997 B&W cameras! They cost over $100 (each) back then and are huge by today's standards. One has a wide and the other a narrow angle lens.

Steve

[sectrix]

you have to connect a diode and capacitor in parallel to the coil

Right, I understand. The magnetic field around the coil collapses when the relay is switched off and induces a reverse voltage across the coil. I almost fried a car stereo's driver unit trying to use a relay. :o

[TravisKy]

Itzik,

Do you have a parts list for building the switch?

[TravisKy]

Also, what if I wanted to be able to watch both video feeds at the same time. Say I am flying through the nose came and have someone else looking at the bottom camera