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405 line PIC generator

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mfd70
(@mfd70)
Posts: 281
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A while ago I programmed a PIC to make the 405 line generator from the old forum;  http://www.forum.radios-tv.co.uk/viewtopic.php?f=109&t=12412

That was about 18 months ago and I'd almost forgot about it, but

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I gathered up all the components I needed, all were to hand except a 6Mhz crystal, but a pack of five cost about £3 off ebay and this morning made up the generator on veroboard. I could see it produced an output but I don't have a modulator to see it on a TV.

However with a bit of experimentation with my Fluke PM5420 I found that setting it to SECAM system L (+ve vision modulation) with an external video input produced a good picture on my old HMV 1400. The Fluke covers all VHF and UHF bands and all colour systems sound spacing etc.

Of course the TV needs attention but I was pleased to see pictures on 405 lines again, for the first time since 1985 in fact.

 
Posted : 02/06/2018 3:17 pm
Nuvistor, Red_to_Black, Nuvistor and 3 people reacted
Nuvistor
(@nuvistor)
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There is not much on that PCB for the job it’s doing, impressive.

Now for the dumb question, I am good at those, why the double staircase image on the Scope is just the scope not triggering or something I am completely missing?

Frank

 
Posted : 02/06/2018 6:14 pm
mfd70
(@mfd70)
Posts: 281
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The double staircase is from another pattern provided in the PIC program (not the one on the TV screen) a crossed grayscale. The 'scope is showing all lines.

 
Posted : 02/06/2018 9:16 pm
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