As you're no doubt aware, a lot of pre-recorded video software is now "copy protected", to stop people from making their own pirate copies. In principle, that’s fair enough; having spent millions of dollars making a movie, the producers are entitled to get a fair return on their investment.

What complicates the situation is that the system used to prevent copying involves adding extra pulses to the normal video signal, some of them varying in amplitude or "dancing". Unfortunately, this prevents quite a few TV sets and projectors from displaying a steady picture during legitimate viewing.

In particular, the extra pulses can cause problems with large-screen TVs that display the picture at 100 fields per second (100Hz) to reduce flicker, and also with projectors that perform line and pixel doubling to improve picture clarity. They can cause problems with older TV sets, too.

If you have one of these sets or projectors, the only way to get a steady picture is to somehow remove these extra pulses. The idea is to "clean up" the video and let the set’s sync circuitry do its normal job without interference. And that’s exactly what the original Dr Video project described in the April 2001 issue of SILICON CHIP was designed to do.

This improved version of Dr Video removes more of the copy protection pulses than the original design, for even more stable viewing. It also handles higher quality S-video signals, in addition to the normal composite video handled by the original stabiliser. Finally, it also provides a wider video signal bandwidth, so your pictures won’t suffer any degradation.

Dr Video Mk2 is housed in the same compact low-profile instrument box as its predecessor and runs from a 9V AC plugpack supply. As before, you should also be able to build it for considerably less than commercial stabilisers.