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Date Posted: 03:44:46 02/09/02 Sat
Author: Dave
Subject: Re: scope/tools recomended for studying video signal?
In reply to: Johnny 's message, "scope/tools recomended for studying video signal?" on 19:54:29 02/08/02 Fri

>I'd like some advice on the equipment (scope, ADC
>cards,
>etc) needed to study the composite video signals (and
>of
>course the encodings on them), and to calibrate the 3c.

40Mhz, dual trace scope with time delay as a minimum.

A multimeter can also come in handy to do a DC anaysis of the circuit to make sure all the components are OK and transistors correctly biased.

If your scope doesn't have time delay I had a circuit here for a time delay add on to the scope for video signals. Basically had an LM1881 to detect the vertical sync pulses, and then a timer that could be adjusted to produce a trigger pulse to the scope just before the start of the next vertical sync pulse. The pulse could then be adjusted anywhere along the video signal to allow the video signal to be viewed with a large degree of magnifaction.

This of course depends if the LM1881 can sense the sync pulses in the video signal. My scope has time delay but I've seen it in use with another and works quite well.

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