I have a small signal coming from the camera called vertical sync signal. This signal is so small that my dmm dose not give any value. I have tried to use this signal for switching using npn transistor but failed. Any help ??

 

Generally 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.

 

Ok

Generally 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.

ok than how can i use this signal for switching

 

Well first we have to find out the minimum and maximum voltage of the signal, or the amplitude and baseline.

 

What are you trying to switch? Signal detection for a switch could be done with a comparator such as LM339 or NE555 timer.

 

Here is the v sync signal.

 

Please s

What are you trying to switch? Signal detection for a switch could be done with a comparator such as LM339 or NE555 timer.

please search for eye writer 2 on the forum

 

The LM339 should easily amplify and square off the desired signal.

 

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 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 frequency

 

What is the voltage/div on the scope?
Where is 0V on the scale?

BTW, the frequency compensation on your scope probe needs adjusting.

 

If 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.

 

If 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.

I want to use it for switching