Power / data cable filter?

[Peter_wadley]

http://www.htcustomcables.com/images/vga_krystal.jpg

If you look at the picture above, you see a basic cable...

Im just wondering what the function of the black .. ahh bulge .. is

It is after the actual connector..

 

[kchriste]

It is a ferrite core to help reduce RFI. (Radio Frequency Interference)

 

[Peter_wadley]

I see

Can you please provide a brief explaination of how it works to that?


a web link possibly?

Thanks

 

[Nigel Goodwin]

I see

Can you please provide a brief explaination of how it works to that?

I've always been fairly sceptical they do anything!, but the idea is they form a lowpass filter on the cable, preventing very high frequencies travelling up the cable (it's just a ferrite core).

 

[Bob Scott]

I've always been fairly sceptical they do anything!, but the idea is they form a lowpass filter on the cable, preventing very high frequencies travelling up the cable (it's just a ferrite core).

It is a one turn coil. Every pass through the core counts as one turn.

 

[Papabravo]

It presents an impedance to an AC signal. The impedance is a function of frequency and satisfies the following

Xl = 2 * π * f * L
where Xl is the Inductive Reactance
f is the frquency
and L is the inductance of the wire going through the core, one time only

As you can see whatever the inductance is it attenuates high frequencies better than low frequencies. As monitors use more and more pixels the vertical amplifiers need to cover a wider bandwidth. Do a back of the envelope calculation for your screen resolution times 30 frames per second to get some idea of the bitrate that may be present on the cable. As Nigel said however, I've never seen any actual data on what those slugs do for you. It's probably the Chicken Soup theory. Can't possibly hurt, and it might help.

 

[Peter_wadley]

So the data cables are actually wound around a the core in there?

Or is the core just around the data cables?

 

[hackableFM]

The core is around the data cables, I only know for sure after it had me wondering and I took a sharp craft knife to one to find out!

lol..

hackableFM.

 

[Papabravo]

In case you missed Bob Scott's succinct description, I take the liberty of repeating it again in hopes that repetition will make it through the thicker skulls.

It is a one turn coil. Every pass through the core counts as one turn.