ramesh@amdcad.UUCP (N.Ramesh) (11/22/85)
I had recently requested advice on adding a direct video input to a standard TV set. As a newcomer to the net I was quite surprised by the number of responses I received and would like to thank all of you. I will post the summary in a separate posting. The principal difficulty as pointed out by many of the contributors seems to be the fact that most of the new breed of TVs do not have an isolation transformer between the mains and the TV chassis, making it a potential hazard to attach any other piece of grounded equipment to it. The solution generaly proposed is to add an external isolation transformer. I checked around and found that a suitable isolation transformer with about 110VA capacity costs around $50. My questions are: 1. Is anyone aware of a method to connect a video signal (RS 170 ?) between two pieces of equipment with different ground potentials (galvanicaly isolated connection)? The obvious choices that come to mind are to use a transformer (what about DC restoration and bandwidth ?) or an opto-isolator (libearity?, bandwidth?). 2. How do TV studios which use a large number of video/audio equipment ensure a common signal ground for all of them wthout causing ground-loops etc? Do they float all the equipment? Interested in your responses.. N. Ramesh Advanced Micro Devices, Sunnyvale, CA PH: 408 749 4726