Video Switcher

[ormo]

I am creating a device that will allow me to switch between several RCA composite video inputs into one output of the same type. With each input there is the signal and the ground. Can I just connect the grounds of the signals together and run that one to the output along with the signal from the switch (fig. 1) or do I need separate switches for the ground and the signal?

Figure 1

 INPUTS
┌-G S--o
|
├-G S--o__      OUTPUT
|         \--o-----S
├-G S--o          ┌G
|                 |
├-G S--o          |
└-----------------┘

Each 'G S' pair is an input signal (ground and signal)
The array of o's are the switch contacts

Please excuse the crude diagram, I do not have access to any circuit graphic producing software at the moment.

 

[ormo]

Does anyone know if it's ok to combine the grounds on several composite video inputs and just switch between the signals?

 

[blueroomelectronics]

Common ground is fine for your video switch. Cost you less to buy a 4 way SVHS switcher and the quality would be better than composite.

 

[ericgibbs]

Does anyone know if it's ok to combine the grounds on several composite video inputs and just switch between the signals?

The problem to be aware of, are ground loops which could cause picture ripple or image cross talk.

The only sure way is to try it.

Are the remote video sources powered by their own psu's.?

 

[ormo]

Thanks for the advice, this is just a little device to switch between the inputs of a couple of games consoles with composite video output

 

[Nigel Goodwin]

Thanks for the advice, this is just a little device to switch between the inputs of a couple of games consoles with composite video output

Your diagram looks perfectly fine - no need to switch the ground, and it's probably a bad idea to do so as most items will be double-insulated.