New to ferrite beads

The bead is intended to intensify the flux surrounding any current passing through the hole. This is a simple way to add inductance to a conductor. If you wrap the conductor around the outside and pass it through a second time, you get almost 4 times the inductance of a single pass (up to the frequency where the permeability rolls off). There is some total number of amperes (usually around 3) passing through the hole, that will saturate the bead and greatly reduce the effective inductance.

And, be aware that beads are for "choking off" rather high frequency signals ... they do nothing in the Hz to kHz range.

Hi, Ant. I thought you were using SMT for this. I would guess you're using the beads recommended by Bel in their appnote. Glad you asked them -- they didn't specify a P/N.

So if you're going mixed, and they didn't specify number of winds, place two lands for a jumper wire about 0.3" or 0.4" apart on your board like a small axial resistor, then during assembly, thread a 22AWG jumper wire through the donut, and insert the two ends of the jumper into the pad holes. Cinch dowm the two ends, and solder. You're done

-- you've got your beads. If they did recommend number of winds, then use the gauge they specified and do that number of turns through the bead, and then solder in place as above. The beads will cut the edge off the higher frequency stuff (above the dreaded "PowerPacket" band of

Of course, if you're going SMT, it would have been better to use an SMT ferrite bead. It mounts just like a small SMT inductor.

Good luck Chris

Thanks all of you for your replies.

They did not specify the number of turns so i'll simply just thread the jumper through the bead and solder the ends =)