Keyboard RCA video out... TV damage?

[Gleix]

I'm putting together some keyboards with video out jacks (RCA) that plug straight into TVs, projectors, etc...

I'm wondering if anybody here knows if it is at all possible for these to damage televisions? I've tested the outputs on the living room TV for hours (memorizing!) and haven't found any problems.  I'm just making sure in case anybody knows, though.  The output is similar to the one's you see on some SK-1 videos on youtube. 

When the video is plugged in TVs won't register it as an actual "source" so the little "Video 1", "AuX", "Line 1", etc...will remain visible.

[kitsophrenik]

im confused!

what do ya see ont he screen when plugged in? is it a similar effect to a wobblevision project?

[Gordonjcp]

it's unlikely to do any damage, but I suppose it's possible.  Since it's not generating a stable sync pulse, the scan oscillators in the TV won't lock on and this could end up doing weird things to the line output stage.

You could build a sync generator circuit and use its blanking output to gate the "video" signal to the TV, which would give you a much more stable and controllable display.

Here's a simple circuit you could try:
http://www.intio.or.jp/jf10zl/tvosc.htm