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Ntsc sync seperator kit for stable oscilloscope trigger


What is for sale: Ntsc sync seperator kit for stable oscilloscope trigger
NTSC Sync Seperator Kit for Stable Oscilloscope Triggering
Have you been frustrated by video waveforms which are difficult to display on your oscilloscope? Do you have to readjust the trigger level every time the scene changes? If so, the solution to your difficulty is at hand.
This kit provides a simple circuit that will allow a triggered sweep oscilloscope to provide the most important capability of a video waveform monitor, a stable display of the video waveform. The video waveform is the most complex waveform we are likely to experience. Because of its constantly changing level and its many different short duration components it is difficult to obtain a stable display using conventional AC, DC, high pass or low pass trigger coupling. A stable display makes analysis and adjustment of video processing and transmitting equipment much easier.
Many of the oscilloscopes that are sold for use in servicing video equipment have trigger positions for viewing waveforms at a horizontal or vertical rate. Even if you have this type of scope, you may want to build this circuit because it offers more display options and also allows the synchronization (gen-lock) of a video device with an external sync input to another video source.
Many high quality scopes intended for uses other than video servicing and many excellent scopes available on the surplus market do not have provisions for stable triggering on video signals. With the addition of this simple circuit, stable displays are possible on any triggered sweep scope.
The device will allow a triggered sweep oscilloscope to display a stable video waveform which is triggered on each field, each odd field, each even field, or each line. With an oscilloscope that includes delayed sweep, a stable display of several lines, one line, or just a portion of an individual line is possible. This is particularly useful for examination of vertical interval test signals.
The circuit uses an LM1881 video sync separator integrated circuit. This IC strips timing information from NTSC, PAL or SECAM video signals, and provides composite sync, vertical sync, odd/even field, and burst/back porch outputs. The device operates on 5 to 12 volts DC and accepts a video input signal between .5 and 2 volts p-p. The 10k input impedance will not load the video line when it is connected. The device draws less than 10 ma making it suitable for operation from a simple voltage divider, internal source or even a 9 volt battery. The device is available in an 8 pin plastic DIP as part number LM1881N.
This should take about 1/2 hour to lay out and build for anyone familiar with electronic construction. I have included a photograph of the IC installed in a Tektronix Type L vertical plugin.
Another use for this circuit is to strip sync information off a composite video signal to provide composite sync to a video device that provides for an external sync signal input. This will allow you to gen-lock two video sources together for mixing, switching, or character insertion.The LM1881 packs a lot of capability into a very small device and could also be used as the foundation for other equipment such as a video signal processor, transmitter sync stretcher, and character insertion.
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Ntsc sync seperator kit for stable oscilloscope trigger