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| i wonder.. https://forum.lddb.com/viewtopic.php?f=16&t=58 |
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| Author: | yazorin [ 03 Oct 2011, 04:07 ] |
| Post subject: | i wonder.. |
since they now have record players that read the record with a laser would it possible to for someone to rig up a laser to read a CED |
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| Author: | publius [ 03 Oct 2011, 07:12 ] |
| Post subject: | Re: i wonder.. |
More than possible. There was such a thing at the RCA pressing plant, for checking the quality of the master discs without a risk of damaging them. |
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| Author: | rixrex [ 04 Oct 2011, 04:56 ] |
| Post subject: | Re: i wonder.. |
It would be an interesting effort. Possibly it could be done with an adaptation of the CED stylus arm and stylus cartridge redesigned to hold a laser device. The laser would not need more than a focusing motor, as the motors to move the arm exist separate from the arm in CED players and operate via signal from the stylus. So that would all have to be worked out. The other thing to overcome would be to design a laser that would read the disc's grooves, which are variable peaks and valleys situated between level crests that the diamond stylus tip rides on. The stylus itself doesn't do the work of transcription, but a titanium electrode within the stylus does, per this description I'm quoting entirely from the CEDmagic website (thanks go to Tom Howe): CED stands for Capacitance Electronic Disc, which refers to the method used to encode the video and audio information on the disc surface. Capacitance can be defined as the ability of two adjacent conductors to store electric charge, and in the CED system these adjacent conductors are the carbon-loaded disc and the thin titanium electrode deposited on the diamond stylus. The mathematical formula for capacitance contains several variables, but with the CED system these variables are all nearly constant except one -- the distance between the electrode and the surface of the disc immediately under it. Within the grooves on the disc surface are microscopic peaks and valleys, several times smaller than the diamond stylus, which rides smoothly on the crests of several adjacent peaks. But the electrode is much smaller than the stylus, so the distance between the electrode and disc surface is constantly changing as peaks and valleys pass underneath. This varying distance produces a varying capacitance, from which the audio/video signals are eventually decoded by the player's signal processing circuitry. You see, the discs itself is a carbon impregnated disc charged with electrical current that the stylus tip senses. So a laser would not do that, but instead would have to reflect a beam off the groove probably at an angle to be picked up by a laser reading "eye". I'm certain that such a device it would fit within the area currently taken up by the stylus cartridge of the stylus arm device, as these cartridges are significanlt larger than any phonograph stylus cartridge. But then the question is: Why do this? Since the current design works well, and the stylus cartridges can be rebuilt to original specs, the only benefit I can see is that the discs would not wear. In actual practice, the dics will still last a long time if kept properly and not abused. I doubt very much that any one collector would play a disc so many times as to wear it out. The RCA estimate was 500 good plays for a disc. That's why you don't want to buy ones that were rentals, except maybe if they were from small town or rural rental places where very few had CED players (which is where I've found still good discs). Of course, the other reason to do a laser adaptation on a CED player is simply for the scientific exercise and experience of doing it, which often is enough reason by itself. |
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| Author: | beetlescott [ 28 Oct 2011, 05:57 ] |
| Post subject: | Re: i wonder.. |
Yes, I guess it would, but if you think about it, the concept of 17 years of research, they were able to get a great picture and really good (for the time) stereo sound. I mean think about it, I have bought these movies, many that have NEVER been opened and played, popped them into a player that hasn't played for years, and I'm watching a movie off a vinyl record! Yeah some of the discs have placed in them that jump or skip, but if you are careful in your collecting, you can have a really quality collection of movies. The occaisional skip can, most of the time, be played on the SJT400 and play it back a few times and many times, the skip is gone. Just a thought. |
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| Author: | vinylcollector [ 28 Oct 2011, 22:51 ] |
| Post subject: | Re: i wonder.. |
When I first heard about the Laser record players, I thought it was quite the thing, until I found out they only play black vinyls. Picture disc records, and coloured vinyl won't work in them (the laser won't recognize them) which are things I collect. CED shouldn't be a problem though as the discs are black. |
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| Author: | rixrex [ 29 Oct 2011, 06:02 ] |
| Post subject: | Re: i wonder.. |
I'm sure it's very possible with modern technology, but then who'd do it? The CED market is really limited, unlike the LP market, which is almost every single one of the baby boomers on up through the 1980s. It's millions of people, not a few hundred. |
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| Author: | cessnaace [ 06 Nov 2011, 06:49 ] |
| Post subject: | Re: i wonder.. |
yazorin wrote: since they now have record players that read the record with a laser would it possible to for someone to rig up a laser to read a CED The only player that I've seen that used lasers to read the grooves of a vinyl record used a series of 5 lasers and cost $10,000!!! Too rich for my blood. lol. STAY AWESOME! 
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