Two cameras wired through relays??

[darrenervine]

I am still in the design stage of my first ROV and I am addressing the video portion of the build.

I would like to have two cameras, one facing front and one facing backwards.
I plan on using 6" domes to house each ccd camera.
The front camera will be movable on two planes via servos and the rear will be fixed.

I would like to toggle between the two views, but do not need to see them both at the same time.

My limited electronic wiring knowledge leaves me stumped on the best way to achieve my goal.

I was going to use a relay to turn the signal on and off between the two cameras.
Instinct is telling me to use the relays to turn off the power to the camera that is not being viewed so I save on power.
But do I turn off the video feed too or just cut the power?

or...

Do I just use the relays to toggle the feed on and off and leave both powered?

or cut power and feed via same relay?

I see baluns are the way to go too...
Any thoughts, suggestions or basic wiring diagrams are greatly appreciated...

Thanks
DOE

[electronicscrazy]

I would suggest a circuit like this, which is what i'm going to use.

sorry for the bad wiring (first time using it).

[darrenervine]

Thanks.
My limited knowledge makes it hard for me to follow the breadboard layout but i can take it into someone i guess..
Does this circuit, cut the power, cut the video feed or cut both?

Thanks
Darren

[KR2_Diving]

Hello DOE,
From the data I have seen, the power it takes to run a camera is negligible at best, so it is likely not necessary to cut power. (In fact, it may actually be a bad idea to cut power depending on the boot sequence of the camera. The delay it takes to re-establish power, then focus, may not be worth the hassle of disconnecting the power.) However, cutting power to your lights might be worth it!

That being said, now you need to determine you video feeds/ tether capacity.

Personally, I am hoping to have 3 cameras on my system, all sending feeds to the surface via Baluns.
I'm hoping to use this part: http://www.pimfg.com/Product-Detail/NVA-603-WH One of these mounted in the ROV and one on the surface. This part is suppose to be for video and audio connections, but I hoping all 4 ports will be suitable for video.

This will require me to have 2 wires for each camera in my tether, as I plan on selecting the feed on the surface using a contraption such as this video switch: http://www.maplin.co.uk/audio-video-sou ... ctor-33143

This will allow me to manually switch between the video feeds. (I have even considered plunging all the feeds into a home cctv security system to record all the feeds at once... but, that involves more money!)

If you don't have the spare wires in your tether, then I don't see why a relay wouldn't work. You may sacrifice the video quality when running the feed through the relay... but that would be easy enough to test once you had a few basic components.

Hope this info is useful!

Ryan "KR2_Diving"

[electronicscrazy]

it is designed to switch power or video but it depends on how you wire it really, i'm hoping to switch the video feed with it

[darrenervine]

I was most likely going to use the Sony PS2 controller for movement. One of the buttons would control the selection of camera.

Essentially the right side joystick would be for thruster control and direction and the left thumb joystick to control the servo's that move the camera.
The "shoulder" button, as it is referred to on the controller would be the toggle on/off for camera seletion.

Your points are excellent about the power shut off, hadn't thought of that and frankly is exactly why these forums are great.

Since I am still in desgin stage, I have not yet determined the parameters of the tether.

I am in Toronto, Ontario, Canada and we have some awesome stores here for electronics/surplus.
One has an excellent inventory of Sealed Lead Acid (SLA) batteries that would work really well for on-board power/ballast.

I am trying to determine what I want on the ROV first and then move up the design process for other decisions.

Really like to have two 6v on-board SLA's (dedicated to thrusters, LED lights and actuator arm) split across two ABS/PVC pipes....for balance.
Need to do more research on the "explosion" scenario that I keep reading about with SLA that are contained without airflow.

Add a small lithium battery to power the cameras to avoid thruster signal interference.

This way I can have a minimal tether, thinking CAT5, to the surface...

Thoughts??

Darren

[thegadgetguy]

A single CAT5 is great for mobility. It really depends on how you control scheme works. A relay control system will need more wires than one CAT5 cable can provide. If you go with a serial interface like RS-232 or RS-485, you still will have enough wires left over for both camera feeds to run up the tether.

[darrenervine]

For the RS-232 are you just referring to how it connects, ie the plug?
25 wires would be good that is for sure, but is the cable flexible enough and what is the gauge of each wire?

Darren

[thegadgetguy]

I was actually referring to using the wires in the CAT5 for transmitting an RS-232 signal. You only actually need three wires for an RS-232 connection with, say, an Arduino. A parallel port on a computer that connects to a printer does use the RS-232 protocol, but many of those extra pins are for specialty applications. In the end, the only ones that really matter for sending data are RX,TX, and of course Ground. It's the same deal for RS-485 - only three wires are required (though it works a little differently than RS-232).

[darrenervine]

although very interested in the Arduino as an option....it is way beyond me right now....

Thinking a bit more on the mechanical route....relays etc...
I guess finding a tether with enough wires and correct gauge will be the trick...