what does fb denote on a circuit board?

[lifelessregrets]

so i remember reading the name on the schematic my company has but a 13 hr day killed my memory and the awe of another 12 hr saturday is killing my soul. my real question tho is what is fb (something bead i remember that) and what does it do in the circuit, im in school to be an ee and like to know what im dealing with when im assembling circuits weather or not my boss wants me to know. idc if i brake contracts i must know lol.

just dont tell them

[skwonripken]

It may be ferrite bead.

[unhinged]

Aww I'm so sorry that you have to work so much. I agree that too much work actually hinders creative thinking!

Okay so on to your question. You sound like you want a short version, so here is what it basically is.

What you are referring to is "FB" or ferrite bead. Like an inductor, it is a passive low-pass filter. It is usually used to provide decoupling. It can filter out high-frequency signals (specified in its spec sheet) so it has its uses as a low-pass filter or noise control. Basically, it has high resistance when there is high frequency and very low resistance when there is low frequency.

In fact, when used with a bypass capacitor in a circuit, it provides excellent decoupling to a circuit. In the spec sheets of a specific type of FB device, you can find the frequencies at which the FB would have the highest resistance.

The circuit equivalent of an FB is a resistor in series with an inductor.

Other names for FB: Ferrite beads are also called ferrite blocks, ferrite cores, ferrite rings, ferrite EMI filters, ferrite chokes.

The FB or ferrite bead is like a muffler. Suppose you are trying to have a conversation with your friend at a party, but because other people are also talking/interacting with each other noisily, you are having difficulty communicating - but if you filter out the high frequencies, you can hear your friend better. There are many uses for ferrites. The high frequencies from your cell phone that you can hear sometimes right before it rings can be choked with ferrite beads. Airplane radios uses these to block off the signals from other transmitters when it is trying to communicate with the tower.

If you want to use ferrite beads for your circuit, you are going to need to figure out what frequencies you want to block and what is a high enough resistance to block these off for your circuit. The manufacturers of ferrite beads put these informations in their data sheets.

[Roger]

fb is ferrite bead. These attenuate high frequencies to prevent unintended oscillations in a circuit.