Theory and practical app of ferrite bead on 12VDC

Discussion in 'General Electronics Chat' started by poopscoop, Mar 31, 2013.

  1. poopscoop

    Thread Starter Member

    Dec 12, 2012
    From my limited understanding, a ferrite bead over a power cable is used to reduce the tendency of the cable to become an antenna, and broadcast any fluctuations in current (voltage?) as RF interference. This is especially important when connected to a SMPS, and may be required by FCC regulations.

    Correct? If not, where am I wrong?

    I have no real understanding of how the bead reduces fluctuations. If someone can shed some light on that, I would appreciate.

    Now for the practical application: I have a "Fish finder" that includes a large, annoying ferrite bead on the power cable. It's powered by 12VDC, and I imagine the actual unit has a 12v-5v SMPS on board. In this instance, is the ferrite bead simply to reduce harmful interference FROM the unit, or does it isolate and reduce any outside fluctuations before they reach the power supply? IE, if I omit the bead, will it negatively impact the system?