|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
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
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