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Vintage Television and Video Vintage television and video equipment, programmes, VCRs etc. |
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12th Jan 2019, 12:21 am | #21 | |
Dekatron
Join Date: Jul 2008
Location: Kington, Herefordshire, UK.
Posts: 3,670
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Re: External Teletext Decoder. Is there such a thing?
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12th Jan 2019, 12:37 am | #22 |
Octode
Join Date: Mar 2011
Location: Sheffield, South Yorkshire, UK.
Posts: 1,453
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Re: External Teletext Decoder. Is there such a thing?
There are a couple of such devices toward the bottom of this page: https://www.radios-tv.co.uk/radios-t...on/#more-36170
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12th Jan 2019, 6:21 am | #23 |
Dekatron
Join Date: Jun 2015
Location: Biggin Hill, London, UK.
Posts: 5,208
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Re: External Teletext Decoder. Is there such a thing?
As others have said, external 'set top box' teletext decoders certainly existed. I have a couple.
A neighbour where I used to live built the Wireless World one when it was published and gave it to me many years later. It uses the old Philips chipset (SAA5020/5030/5040/5050). I think it has ultrasonic (not IR) remote control. I found the Radofin one at a radio rally some years back. I've never got round to tinkering with it, but I think again it uses the Philips chips Although I don't (yet) have them, there were of course teletext decoders for the BBC microcomputer. The Acorn one used some of the Philips chips and connected to the computer 1MHz bus. There were third-party one using the later Philps chips (SAA5243, etc) with an I2C interface (bit-banged over a couple of lines of the user port). Using a teletext PCB from some TV model connected to a computer that bit-banged an I2C bus was not uncommon at one point. I did it and probably still have the unit I made somewhere. |
12th Jan 2019, 3:17 pm | #24 |
Hexode
Join Date: Aug 2016
Location: Edinburgh, Scotland, UK.
Posts: 262
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Re: External Teletext Decoder. Is there such a thing?
There is of course the fantastic vhs-teletext software, which can try and recover as much of the original teletext pages from VHS tapes using a WinTV capture card and some clever software on a modern computer.
It takes a bit of time to process the signal, but the resulting files can be played back in an emulator that acts just like the original teletext. (Note: I'm not in any way involved with the software, except that I have used it in the past and was mightily impressed by it). |
12th Jan 2019, 3:36 pm | #25 |
Dekatron
Join Date: Apr 2012
Location: Wiltshire, UK.
Posts: 13,998
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Re: External Teletext Decoder. Is there such a thing?
There were certainly external Teletext-decoders available - I remember travel-agents having them! Forget the manufacturer, but they were a slim aluminium box that was designed to have the telly sat on top: suppose in modern parlance it would be a "Set-bottom box". Some also had a built in dial-up modem and keyboard-socket for connecting to central booking/reservation systems.
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12th Jan 2019, 3:39 pm | #26 |
Nonode
Join Date: May 2007
Location: Redruth, Cornwall, UK.
Posts: 2,573
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Re: External Teletext Decoder. Is there such a thing?
Thanks for the link andrewferguson. It looks very interesting. I have quite a few old VHS cassettes from the 1990s and possibly a few from the late 1980s with many TV programmes recorded off air, so it would be great to see if there's any recoverable teletext info.
Regards Symon. |
12th Jan 2019, 3:45 pm | #27 |
Nonode
Join Date: May 2007
Location: Redruth, Cornwall, UK.
Posts: 2,573
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Re: External Teletext Decoder. Is there such a thing?
Hi.
Yes, I actually picked up one for £1 from the local car boot sale a few months ago. It is made by Ayr and has a built in front end (tuner and IF). I think the decoder itself has the Mullard/Philips chipset. I haven't actually opened it as yet but will try to find it this week and post a few pics. Regards, Symon. |
12th Jan 2019, 4:04 pm | #28 |
Pentode
Join Date: Jan 2010
Location: Rotherham, South Yorkshire, UK.
Posts: 201
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Re: External Teletext Decoder. Is there such a thing?
thanks I would be interested to see one
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12th Jan 2019, 4:40 pm | #29 | |
Dekatron
Join Date: May 2010
Location: Greater Manchester, UK.
Posts: 18,713
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Re: External Teletext Decoder. Is there such a thing?
Quote:
Teletext and Viewdata looked similar, using the same display spec. Often using the SAA5050 graphics chip.
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12th Jan 2019, 4:51 pm | #30 |
Dekatron
Join Date: Apr 2012
Location: Wiltshire, UK.
Posts: 13,998
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Re: External Teletext Decoder. Is there such a thing?
No the ones I recall definitely had Teletext decoders and an antenna connection as well as the dialup thing. You could watch ordinary TV on the things! I don't think the dialup was for Prestel, from memory it went to the travel-agent's mainframe, from which you could then _also_ connect to a few airlines' reservation-systems.
(I remember being impressed by this when it was used to book flights to the US for my father in the late-1970s. Two different airlines used in each direction, with a layover in New York included - all booked as one transaction. What diabolical sorcery was this?) |
12th Jan 2019, 4:51 pm | #31 |
Dekatron
Join Date: Feb 2005
Location: West Cumbria (CA13), UK
Posts: 6,127
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Re: External Teletext Decoder. Is there such a thing?
As did Mode 7 graphics on the BBC Micro, which was exploited by the Teletext adaptor designed for it.
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12th Jan 2019, 5:42 pm | #32 |
Heptode
Join Date: Oct 2015
Location: Gloucestershire, UK.
Posts: 719
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Re: External Teletext Decoder. Is there such a thing?
Travel agents used Prestel but had access to a closed group for their use.
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12th Jan 2019, 5:59 pm | #33 |
Dekatron
Join Date: Aug 2011
Location: Newcastle, Tyne and Wear, UK.
Posts: 11,556
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Re: External Teletext Decoder. Is there such a thing?
I made the accidental discovery many years ago that my Panasonic NV-F70 VCR could at least partly replay teletext data from recordings - not seamlessly / reliably like the original off air recordings, but what I was mainly interested in was using it to recover / identify the time / date at/on which the original recording had been made. That normally worked quite well. It's interesting to try to browse through the teletext news pages of the day as well.
Afterthought: Does this work with DVD recordings made from analogue off-air transmissions? I have never tried that. I think by the time I had an HDD/DVD recorder it already had a DVB tuner, so all my DVD recordings are from DVB. |
12th Jan 2019, 7:39 pm | #34 |
Pentode
Join Date: Jan 2010
Location: Rotherham, South Yorkshire, UK.
Posts: 201
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Re: External Teletext Decoder. Is there such a thing?
any one have information on this its a decoder that's on ebay but not sure its what I am looking for https://www.ebay.co.uk/itm/Colby-Vid...gAAOSwbiFZOu8d
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12th Jan 2019, 7:54 pm | #35 |
Nonode
Join Date: Oct 2008
Location: Warsaw, Poland and Cambridge, UK
Posts: 2,677
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Re: External Teletext Decoder. Is there such a thing?
If you're wanting to decode teletext data from VHS recordings, that's fiendishly difficult and has only become feasible recently thanks to modern digital signal processing techniques working on captured video data. Any external decoder from 'back in the day', such as those mentioned here, has next to no chance of working on VHS, a small chance of working on S-VHS, and would probably work quite well on laserdisc.
Chris
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12th Jan 2019, 7:59 pm | #36 |
Pentode
Join Date: Jan 2010
Location: Rotherham, South Yorkshire, UK.
Posts: 201
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Re: External Teletext Decoder. Is there such a thing?
I want to get pages off laserdisc, its a fine clear signal works fine on my tv so a old external decoder should have no problem
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12th Jan 2019, 9:07 pm | #37 | |
Dekatron
Join Date: Dec 2007
Location: Haarlem, Netherlands
Posts: 4,199
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Re: External Teletext Decoder. Is there such a thing?
Quote:
Travel agencies over here, used standard CTX colour sets with a Viewdata system built in by a third party. |
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13th Jan 2019, 3:16 am | #38 |
Hexode
Join Date: Mar 2014
Location: Peacehaven, East Sussex, UK.
Posts: 278
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Re: External Teletext Decoder. Is there such a thing?
I had the complete teletext/ view data set of boards that were fitted to the Thorn 9600 chassis I think, the memory is hazy now but I should still have the manual somewhere.
It consisted of the Philips made ( I assume, it wasn't Thorns) teletext board which was about 15cm square glass fibe and double sided.with the 1st gen of chips and several connectors. It interfaced to the viewdata board which was sandwiched on one side of the teletext board and another board was the phone line interface. As I was only interested in the text board I binned the other parts but did make 2 decoders for my friend and I. As we were Thorn group we called Gosport and they sent us TX10 remote handsets and the receiver part and trim from the set. I still have mine in the loft. |
13th Jan 2019, 12:56 pm | #39 |
Octode
Join Date: Apr 2007
Location: Hampshire, UK.
Posts: 1,577
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Re: External Teletext Decoder. Is there such a thing?
Many of B&O's TV sets of the Teletext era made the output of the Teletext decoder available at the SCART socket, the idea being that it was then possible to record TV programmes complete with Teletext subtitles. That's one idea, but the results may well be in monochrome.
More usefully, the Thomson / Ferguson ICC5 chassis encoded the output of its Teletext decoder as PAL, it wasn't presented as RGB to the screen. As well as this making the text display washed out, fuzzy and subject to the whims of the user colour control, it means that the fully decoded teletext page images are present in the receiver as CVBS and in colour. It may even be present at the SCART socket like this, who knows? Finding an ICC5 that still works, there's the challenge... |
13th Jan 2019, 1:33 pm | #40 | |
Dekatron
Join Date: Jun 2015
Location: Biggin Hill, London, UK.
Posts: 5,208
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Re: External Teletext Decoder. Is there such a thing?
Quote:
I have a NordMende-badged ICC5 TV here with various faults. I am thinking of stripping it for useful parts fairly soon (like the teletext ICs) but if there is any interest at all in it I would offer it complete here. |
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