I have 2 Composite video outputs ( DVD & Set Top Box ) but the TV has only one Comp. Video IN. Can I combine them in any way ? I dont wish to use a switch if I can get away with it .....to complicated for other members of household - flicking a switch is fairly high tech !!!
Only one device would be in use at any one time, but power would still be applied to both units. Can it be done by just combining the leads ? Can I expect any problems or even damage ? Can I knock up a small combiner with minimal components ?
Assuming you mean only one unit is operating at a time, it'll almost work, except each video output is designed for 75 ohm load, if you hook up 2 outputs together, as well as the TV, then each output will see 2 x 75 ohm loads in parallel, or 37.5 ohms, which will overload the output and result in a poor picture, although the TV may be able to compensate somewhat.
To alleviate this you could use a 33R resistor in series with each of the 2 signals. Note that if you disconnect one of the devices, the picture will also go bad.
In this case, the answer is most almost certainly NO. If the STB and DVD are powered up then they will be both be generating a signal be it a blank screen, menu screen, screen saver etc
You *might* be able to get away with combining the outputs if you only have one device powered on at a time. But that would require you to use the power switches accordinly, and that is more complicated than a simple source switch. If they switch both on at once then you'll most likely get a grabled display, and then if they'll probably freak out that they have broken something given that a simple switch is too high tech for them.
problems or
Damage, most likely not.
Get a switch box, it's the best solution. Put big DVD & TV labels on, they'll soon get the hang of it. If they can't figure it out they go without :->
Even if you got a new TV with multiple inputs, you'd still have to push a button to select different inputs, so there is no real advantage there either.
I'd suggest that if flicking a switch is too high tech for them then turning on the TV in the first place will be well beyond their ability and hence you have no problem!
Otherwise, I fail to see any solution other than a switch box, unless the OP wants to ensure that only one device is ever switched on at a time, even the 'blank' screen will interfere with the picture from the other device......
Another solution - Run the DVD via the VCR AV in to the RF input of the TV and then the STB to the AV inputs - problem solved!
you CANNOT do this - the signals wouldnt be syncd and as a result you would end up with a total mess.
The switchbox is about the only practical means that I can see to solve this problem, short of changing over the TV for a newer one with multiple inputs.
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