Video Line Sync Trigger Generator Here is
a circuit that will allow you to trigger your oscilloscope on
specific lines in a video signal. This is a feature found in
either very specialized or very expensive scopes and is a must for
anyone who is developing or working with NTSC or RS170 video
systems.
The circuit is based around the National LM1881 and is an
enhanced version of a schematic found in the back of the data
sheet. The LM1881 separates the sync signals from the raw video
and generates TTL level signals. A switch is used to select the
Odd or Even field and the line select logic allows use of the
Digital Knobs circuit. Not shown but implied is the +5 and ground
signals going to the power leads of all devices.
Use judicious layout with the video signals and keep the leads
short.
![VideoSync.gif (21040 bytes)](VideoSync_small.gif)
Click the above thumbnail to view the schematic
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