7
\$\begingroup\$

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 ?

\$\endgroup\$
  • 8
    \$\begingroup\$ The great thing about standards is that there are so many to choose from. [mandatory xkcd] \$\endgroup\$ – The Photon Jun 3 '15 at 2:47
  • 1
    \$\begingroup\$ To make things more confusing, quite a few people draw a ferrite core inductor for a ferrite bead in schematics. \$\endgroup\$ – Nick Alexeev Jun 3 '15 at 3:21
  • 1
    \$\begingroup\$ @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. \$\endgroup\$ – Curd Jun 27 '16 at 7:47
  • 2
    \$\begingroup\$ @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. \$\endgroup\$ – Nick Alexeev Jun 27 '16 at 13:39
  • 1
    \$\begingroup\$ @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. \$\endgroup\$ – Curd Jun 27 '16 at 14:28
10
\$\begingroup\$

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.

\$\endgroup\$
4
\$\begingroup\$

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

\$\endgroup\$
1
\$\begingroup\$

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.

\$\endgroup\$

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.