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Old 25th Aug 2019, 7:58 pm   #1
Karen O
Rest in Peace
Join Date: Jul 2011
Location: Bridgnorth, Shropshire, UK.
Posts: 787
Default Orton PIC video clock

This PIC project displays an analogue clock on a monochrome 625 monitor.

Points to note:

The video output delivers 1V p-p video into a 75R load. Many consumer appliances (e.g. Chinese mini televisions) present a much higher load than this so need an additional resistor across the video output. Try 82R or maybe 100R.

The video signal is non-standard (non-interlaced, no equalisation pulses, no chroma, non-standard frame sync). It'll almost certainly work with older CRT monitors but more modern monitors may turn their collective nose up at it.

If you want to trim the crystal, the location of the trimmer is shown on the circuit. I lack the means to measure the crystal frequency accurately so didn't bother with this.

The text file contains the hex for the program. Just change the extension to .HEX and it should be digestible by PIC programming software.
Attached Thumbnails
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Name:	anaclock.jpg
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ID:	188905   Click image for larger version

Name:	Circuit.jpg
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ID:	188906  
Attached Files
File Type: txt anaclock.txt (9.8 KB, 139 views)
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