ok than how can i use this signal for switchingGenerally speaking, you cannot detect and observe logic signals using a digital multi-meter (DMM).
You need an oscilloscope of appropriate bandwidth in order to properly characterize the signal.
please search for eye writer 2 on the forumWhat are you trying to switch? Signal detection for a switch could be done with a comparator such as LM339 or NE555 timer.
Lm339 will convert this signal to square signal but vsync signal changed rapidly with fps. Does it do any effect on input frequency?The LM339 should easily amplify and square off the desired signal.
Lm339 will convert this signal to square signal but vsync signal changed rapidly with fps. Does it do any effect on input frequencyThe LM339 should easily amplify and square off the desired signal.
I want to use it for switchingIf you are just wanting to determine the absence or presence of such a signal,you can use a tone detector IC like a Lm567.
Another way is to use an integrating network with a long time contant,so it charges up the C to a threshold voltage to trigger a bistable circuit.
If you want each pulse to switch something which then returns to it off state between pulse,thats another thing altogether.