Need Inductor used in D&S Driver Kit

On: Tue, Mar 26, 02 02:20:01 PM

David Asp wrote:

Can anyone identify the inductor that is used in the D&S kit. My kit did't include one and I don't want to build my kit and have it fail right away. The symbol is for an inductor and the parts description is: L1= ferrite bead - property units = ui 850, u max 3000, Bs gauss @10 oer, Curie T in deg C 130, Vol. res. in ohm-cm 1x10^5, Hc in oer 0.3. but what does this mean? I have tried to use this info to look up an inductor with no luck. Please help me find this information so I can finish building my kit.


Dooley - Wed, Mar 27, 02 12:49:31 PM

My didn't have one either so I did not include it and it is working fine. Hope it wasn't important.

Frank - Thu, Mar 28, 02 07:51:08 PM

It was determined that the ferrite bead was not necessary. A few of the older parts lists that I include with the kit still contain the listing for it. Usually I will put a line through it and hand-mark that it is not required -- my apologies for not catching that on yours David. Frank

Colin Kaminski - Mon, Apr 01, 02 09:32:27 PM

In doing a little research I realized that this description does not include the value for inductance. Does anyone know the inductance?

Tom B. - Thu, Apr 11, 02 03:16:16 AM

A ferrite bead is typically a hollow cylindrical bead of grayish magnetic ferrite material. When the bead is slipped over a wire, it partially suppresses high-frequency noise that would otherwise pass through the wire. At high frequencies, the bead/wire combination acts more like a resistor than an inductor, which is why ferrite beads are usually categorized by their operating frequency range and impedance curves rather than by inductance (which is relatively insignificant at high frequency). In principle, you can calculate the impedance curve from the magnetic properties and shape of the bead, but it's way easier just to look up the manufacturer's data, and even easier to just try a few different types to see what works best. Some application notes with ferrite theory here: Sources: sells JW Miller ferrites (

Colin - Thu, Apr 11, 02 03:42:30 AM

So this is used as a RF filter to clean up the signal?

Tom B. - Fri, Apr 12, 02 02:56:36 AM

Yes, most likely to reduce stray RF pickup from connecting wires, which can act like antennas. Proper shielding and grounding are also helpful here.

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