Ok, I'm new in this group, but I can help with this one: 1. Most modern video and chroma delay lines do not use glass SAW filters, they use CCD delay lines built into chips. 2. The delay line for color detection is indeed 1H (64 usec for PAL) long, but the one for video is only about 330 nsec and depends on the set. Its primary role is to compensate for the delay induced by the increased complexity on the color channel. 3. A CCD delay line passes video with a bandwidth of up to 4 MHz (125 nsec per bucket), especially if it is made for S-VHS use. 4. Usually these have a built-in multiplier and PLL and synchronize to an external clolor carrier frequency signal. This automatically implies that you can pull the frequency by pulling the external frequency. I think that a VCO would do that quite well at 4 MHz. 5. The same S-VHS sets also use a 1/2H delay line (32 usec PAL) to satisfy the requirements of S-VHS signal transmission (the mysterious 4-pin connector on S-VHS sets). 6. The best source for a few 'samples' of these, is a local VCR spare parts dealer, after you will smartly sneak a look at the schematics of a popular VCR not more than 3 years old. 7. All delay lines of this type require *serious* filtering at the output to remove the clock bleed in. The manufacturer's data sheets give data for this, but with a part obtained as under #6, be sure to 'eye' the output filter and order the coil with the chip... This is for learning purposes, OK ? 8. A solution for #7 is switched capacitor filtering, if you can afford it. On Sun, 14 Dec 1997, Nigel Goodwin wrote: > In message , XYGAX writes > >Have you thaught of those delay lines they use in TV sets they are analouge > >but I dont know if the delay is a fixed time period but it might be worth a > >look. > > The chroma delay line (PAL not NTSC!) delays one line period, that's > 64uS for PAL 625 line transmissions. It's designed to delay a 4.433MHz > signal, so doubt it could be used for anything else - basically it feeds > the signal into one edge of a piece of glass/plastic and then picks up > the vibrations at the other end. > > The luma delay line is FAR! shorter, I don't know how short but think it > must be around 1uS or less. These seem to work by just feeding the > signal through a long piece of wire coiled around a former, the delay is > the length of time it takes to travel down the wire. Some of the very > old TV's used a piece of coaxial cable (coiled up) as the delay line. > > >Distant memory havent fixed TV's for years and then it was only the power > >supplies and line stagesnothing else ever goes wrong with them.... > > Don't you beleive it! :-). > > >Bet my telly pops now > > I wouldn't be suprised :-). > > -- > > Nigel. > > /--------------------------------------------------------------\ > | Nigel Goodwin | Internet : nigelg@lpilsley.demon.co.uk | > | Lower Pilsley | Web Page : http://www.lpilsley.demon.co.uk | > | Chesterfield | | > | England | | > \--------------------------------------------------------------/ > Peter Lorand Peres ------------------ plp@actcom.co.il 100310.2360 on CIS (please use Internet address for mail) http://ourworld.compuserve.com/homepages/plp "The creed of Inland Revenue is simple: 'If we can bring one little smile to one little face today - then somebody's screwed up somewhere' - David Frost (Note: The above stands valid in all countries until proven wrong)