Hey guys,
I was analyzing a wireless video board that has an analog (composite) video input and output. While doing so, I found that the video feed line has an inline diode. Cathode toward the Video Input side and Anode toward the Video Output side.

The video input goes to both the diode and the wireless board. If the Diode wasn't there, then the video input and output would be a straight through connection.

I am very confused why its there. Can anyone explain this to me?

Thanks in advance.

 

Inserting an image so you can see whats going on and hopefully explain why its there.

EDIT: The connector on top is VIDEO OUTPUT!!!. Not video input. my bad

 

Hey guys,
I was analyzing a wireless video board that has an analog (composite) video input and output. While doing so, I found that the video feed line has an inline diode. Cathode toward the Video Input side and Anode toward the Video Output side.

The video input goes to both the diode and the wireless board. If the Diode wasn't there, then the video input and output would be a straight through connection.

I am very confused why its there. Can anyone explain this to me?

Thanks in advance.

It is probably being used as a switch. A DC forward bias turns it on, and 0 or reverse DC bias turns it off. I just happened to have made this video tonight to describe how to use a diode as a switch.
http://www.youtube.com/watch?v=YBNIq_d56sA

 

Are you sure it is a diode ? Test it with the resistance range of a multimeter. It could be an inductor.

Timescope

 

Looking at the picture, it looks to be a tantalum capacitor, not a diode. Nevermind on the diode switch video...

 

Yep, it's a 100uF 6v tantalum cap in SMD size D.

Sigh, does knowing that make me a nerd?

It's common to use a cap in series with an analogue input.

 

Thank you guys!! That makes total sense.
I appreciate all of your help.