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Many of the schematics I've seen in reference schematics use an the symbol of an inductor as the symbol for a ferrite bead (makes sense).

But I've also seen other variants of it as well. I don't have the IEEE 315 document, but I know that there are somethings that we do in North America that isn't exactly IEEE standards.

enter image description here

Bonus question: Is there a document or source that lists North American standard symbols ?

Nick Alexeev
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efox29
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    The great thing about standards is that there are so many to choose from. \[[mandatory xkcd](http://imgs.xkcd.com/comics/standards.png)] – The Photon Jun 03 '15 at 02:47
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    To make things more confusing, quite a few people draw a ferrite core inductor for a ferrite bead in schematics. – Nick Alexeev Jun 03 '15 at 03:21
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    @Nick Alexeev: Which is perfectly reasonable because a ferrite bead with a wire going through its hole **is** nothing else but a toroidal ferrite core inductor with one turn. – Curd Jun 27 '16 at 07:47
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    @Curd It's partially reasonable to draw a ferrite bead as a inductor, but *not perfectly* reasonable. At low frequencies, a ferrite bead operates as an inductor. At high frequencies, however, a ferrite bead operates as a frequency-dependent resistor because its ferrite core is lossy - intentionally. Here's a good article on the subject: [Ferrite beads demystified](http://www.analog.com/library/analogdialogue/archives/50-02/ferrite-beads.html). – Nick Alexeev Jun 27 '16 at 13:39
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    @Nick Alexeev: ...and the same is true (more or less) for any real inductor. I understand, tough, what you are saying: in a ferrite bead it is intentionally, in other inductors it is not. – Curd Jun 27 '16 at 14:28
  • @NickAlexeev - totally agree with you. I got a schematic today with a 1KH inductor on it! Of course it's supposed to be a ferrite bead with a 1K resistance - but it even had the designator 'L' not FB as recommended by IET guidelines – N.G. near Nov 04 '22 at 14:59

3 Answers3

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The IEEE is a US-founded organization that has brought "North American standards" to much of the rest of the world. Any non-IEEE symbols being used in North America merely demonstrate our inability to fully standardize those symbols on the continent. A copy of IEEE 315 if anyone is looking.

The alternative to IEEE is the Europe-based IEC, and I could not find any information on their preferred standard for a ferrite bead.

The person who assembled those images had no final answer either; simply put, the IEEE's is the only ferrite bead standard I was able to confirm.

MBer
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Not sure about standards, but here's another option I ran across recently on an Atmel schematic. From the first-angle projection symbol on the schematic and other hints I would guess it to be non-North American in origin, most likely Asian.

enter image description here

This is another one (European, I think) that I have used:

enter image description here

IEEE Std 315-1975 has these (both shown in the pirated pdf linked in another answer):

enter image description here

Spehro Pefhany
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The IEC 60617 symbol for a ferrite bead is shown in IEEE 315A, Clause 6.2.11 as follows:

symbol for ferrite bead

The class letter to use in a ref des is E.

SamGibson
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Lawrence Joy
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