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New to ferrite beads

A

Ant_Magma

Jan 1, 1970
0
I'm using ferrite beads to produce a clean voltage supply. The ferrite
bead i ordered looks like a hollow cylinder.

How do i connect this? Do i just use wires run a couple of turns
through the core and solder the wires onto the PCB?
 
J

John Popelish

Jan 1, 1970
0
Ant_Magma said:
I'm using ferrite beads to produce a clean voltage supply. The ferrite
bead i ordered looks like a hollow cylinder.

How do i connect this? Do i just use wires run a couple of turns
through the core and solder the wires onto the PCB?
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.
 
C

Charles Schuler

Jan 1, 1970
0
John Popelish said:
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.
 
C

Chris

Jan 1, 1970
0
Ant_Magma said:
I'm using ferrite beads to produce a clean voltage supply. The ferrite
bead i ordered looks like a hollow cylinder.

How do i connect this? Do i just use wires run a couple of turns
through the core and solder the wires onto the PCB?

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
4 to 21 MHz).

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
 
A

Ant_Magma

Jan 1, 1970
0
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 =)
 
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