Join Date: Oct 2001
Location: Newcastle, NSW, Australia
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Yes folks, it is possible, no transcoding neccesary. At 576P and 480P it looks a lot nicer than SVideo or Composite. Also beats spending silly amounts of money on a line doubler (wish I knew this trick when I had my first 1252!).
I couldn't get hold of a IFB-12 or IFB12A to get progressive scan into my 1252 here in Australia, so I decided to make my own based on instructions for getting an IFB12 to work, and the service manuals.
Its actually very basic. You could run unbuffered video directly from your DVD player, but I preferred to buffer the video with a MAX497 which is one of the few video grade opamps still available in DIP package (for ease of soldering/board design) but it uses a dual rail power supply, so you need to generate a negative supply rail. It is a bit thirsty at 30ma, but doable with a squarewave osciallator + caps + diodes on the 12V rail.
Sync is separated by an LM1881 (a GS4881 would be nicer, and is pin-for-pin compatible, but I had a LOT of trouble sourcing one - it does Tri level sync, but the 1881 only does BI level sync - keep this in mind).
Power is a single +12V rail, which is regulated to +5V for the LM1881 and positive rail of the MAX497, and is switched by the projector as the card is selected (0V is on, +5V is off), which also turns the isolation relays on and off as well.
An odd part of the design is the inclusion of a Medium logic level, which in the projector is generated by a 2.7V zener, but as these are hard to come by, a 3.3V zener fills this role adequately.
If anyone is interested, I can post up the schematic and PCB design, in case you would like to make your own.