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 Playing DVDs with copy protection on old TVs without lines or buzz
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 Return to top of page · Post #: 1 · Written at 3:42:27 PM on 21 December 2017.
Ian Robertson's Gravatar
 Location: Belrose, NSW
 Member since 31 December 2015
 Member #: 1844
 Postcount: 1291

I know I have visited this subject before, but this time I've done something about it!

I have designed, built and tested a combined video signal processor and AV modulator, optimised for early TVs. This box allows you to enjoy any content on your vintage TV at best possible resolution, without buzzes and flashing white diagonal lines.

It strips out all the junk in the vertical blanking interval - stuff that was originally put there to stop you copying it...
It also clamps the signal aggressively and clips peak white excursions to 20% carrier to avoid punching holes in the signal and creating buzz in the sound. The sound carrier is set to the old standard of 25% of the peak vision carrier - the level that your old TVs were designed for. It's designed to tune to CH2 because this allocation is now empty and so my Ekco can pick it up! But it's not hard to change it.

Although it's designed for CCIR 625 line video (PAL) it will work just as well with EIA 525 and, in the US, the modulator can be tuned to 4.5MHz and VHF Ch 4


So far, I have laid down a PCB (SMD) and built 5 prototypes.

Anyone else interested? I've emailed Brad with the PDF.

Legacy AV Modulator


 
 Return to top of page · Post #: 2 · Written at 9:57:54 PM on 22 December 2017.
Vintage Pete's avatar
 Location: Cromer, NSW
 Member since 1 May 2016
 Member #: 1919
 Postcount: 1050

I would love one of these Ian.
Not sure if it will be something I can build though, But I would be wanting one for sure.
Pete


 
 Return to top of page · Post #: 3 · Written at 7:41:20 AM on 23 December 2017.
Brad's avatar
 Administrator
 Location: Greenwich, NSW
 Member since 15 November 2005
 Member #: 1
 Postcount: 5511

Document uploaded.


‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾
A valve a day keeps the transistor away...

 
 Return to top of page · Post #: 4 · Written at 8:15:10 PM on 23 December 2017.
Ian Robertson's Gravatar
 Location: Belrose, NSW
 Member since 31 December 2015
 Member #: 1844
 Postcount: 1291

One of the prototypes has your name on it Pete!


 
 Return to top of page · Post #: 5 · Written at 9:41:23 PM on 23 December 2017.
BringBackTheValve's Gravatar
 Location: Linton, VIC
 Member since 30 December 2016
 Member #: 2028
 Postcount: 210

Ian,

You are a gentleman.


 
 Return to top of page · Post #: 6 · Written at 9:29:26 AM on 24 December 2017.
Vintage Pete's avatar
 Location: Cromer, NSW
 Member since 1 May 2016
 Member #: 1919
 Postcount: 1050

Thank you Ian.
I look forward to seeing this device you have built and seeing images displayed as they should be on my vintage sets.
All the best and merry Christmas,
Pete


 
 Return to top of page · Post #: 7 · Written at 7:53:21 PM on 24 December 2017.
Morren's Gravatar
 Location: Glenning Valley, NSW
 Member since 19 March 2012
 Member #: 1112
 Postcount: 18

Thanks for contacting me on email Ian! The E1 will love it!!


 
 Return to top of page · Post #: 8 · Written at 12:56:54 AM on 26 December 2017.
Robbbert's avatar
 Location: Sydney, NSW
 Member since 18 September 2015
 Member #: 1801
 Postcount: 1074

Surprisingly complex, isn't it...

Excellent idea, although since I don't work on vintage TVs I don't need one.

May I make a suggestion? I notice the audio input is mono, even though every DVD player will be outputting stereo. Is it possible to have a simple resistive mixer with that first op-amp? Or should users make up something of their own?


 
 Return to top of page · Post #: 9 · Written at 11:45:37 AM on 27 December 2017.
Ian Robertson's Gravatar
 Location: Belrose, NSW
 Member since 31 December 2015
 Member #: 1844
 Postcount: 1291

Yes Rob, well if it was easy someone would have done it years ago! I challenge anyone to do it with fewer parts and still have it work on all signals....

The mono input was partly a rear panel real estate issue. I assume you would use a Y cable with it, from the DVD player. That's what I do. However, it's likely that the vintage material you'd be likely to be playing would have mono sound and hence you could simply use the L or R output.

If there is interest though I could add Zweiton stereo to the modulator..... But this box is intended for 50's and 60's TVs (the other reason for mono input) so I would need a really good reason to put in the effort.

For anyone who's interested I still have a few prototype PCBs left. They need a few patches because on the 1st iteration I mis-read the LM1880 datasheet and got the signal polarities wrong.


 
 Return to top of page · Post #: 10 · Written at 1:14:19 PM on 27 December 2017.
Vintage Pete's avatar
 Location: Cromer, NSW
 Member since 1 May 2016
 Member #: 1919
 Postcount: 1050

Lost here???
Vintage tvs are all mono!
So why would you want stereo going into a mono unit?
Later tvs that are stereo and colour dont need a module to adjust the picture or sound?
Its only some 50s and 60s Tvs that do and their all mono!
I have never seen a 50s 60s stereo tv in oz?
Only the radiogram side of things and thats completely separate from the Tv .

Pete


 
 Return to top of page · Post #: 11 · Written at 1:58:56 PM on 27 December 2017.
BringBackTheValve's Gravatar
 Location: Linton, VIC
 Member since 30 December 2016
 Member #: 2028
 Postcount: 210

Hi Pete,

Mixing stereo channels together isn't a bad idea, because often one channel may contain audio content not present in the other.

One example is when listening to people talking on TV and the guy on the left can be heard from the left speaker, while the guy on the right can be heard louder on the right speaker. This gives the viewer some form of spatial effect.

By mixing both channels you ensure the full audio context is reproduced.


 
 Return to top of page · Post #: 12 · Written at 2:17:36 PM on 27 December 2017.
Vintage Pete's avatar
 Location: Cromer, NSW
 Member since 1 May 2016
 Member #: 1919
 Postcount: 1050

But most vintage tvs have one speaker? And the ones that I have seen with 2 are still mono.
When I say vintage tv , I mean 50s 60s , the tvs from the 70s 80s 90s are not what I call vintage, I have another name for the later ones ,but I cant write it on here😆


 
 Return to top of page · Post #: 13 · Written at 2:44:11 PM on 27 December 2017.
BringBackTheValve's Gravatar
 Location: Linton, VIC
 Member since 30 December 2016
 Member #: 2028
 Postcount: 210

Yes, but modern audio is transmitted over two channels, and the full content may be lost if you only input one channel from your DVD, STB etc.

By "blending" the two audio channels into the AV Modulator, you will be assured of receiving both channels through your mono TV speaker.


 
 Return to top of page · Post #: 14 · Written at 2:47:50 PM on 27 December 2017.
BringBackTheValve's Gravatar
 Location: Linton, VIC
 Member since 30 December 2016
 Member #: 2028
 Postcount: 210

Pete,

As suggested by Ian, a Y cable will do the job.


 
 Return to top of page · Post #: 15 · Written at 10:29:23 PM on 27 December 2017.
Vintage Pete's avatar
 Location: Cromer, NSW
 Member since 1 May 2016
 Member #: 1919
 Postcount: 1050

Oh, all my tvs are 50s or 60s .
Im happy with the sound .
I dont need stereo, mono is fine.
The thing I love about Ian's device is the picture quality.
No lines etc etc, which you do get on some vintage tvs when playing new content.


 
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