I was taught, solid lines mean laminated iron core, dashed means powdered or ferrite.
Occasionally you'll see a single line, which might imply a smaller core (or a lazy drafter).
A single line with an arrowhead means a variable reluctance coil (e.g., slug tuned).
Three lines might simply reinforce the concept of a laminated iron core (proactive drafter?), or provide a symmetrical way to connect a grounding wire to the core (common in sensitive applications, audio amps, test equipment..).
Sensitive applications may also have shields, usually indicated as dashed lines between a given winding, or set of windings, and the core.
There's also the uncommon tradition of a diagonal slash at each end: . / . /--------------/ . /--------------/ . / to indicate a square loop (magnetic amplifier type) core.
Tim
--
Seven Transistor Labs
Electrical Engineering Consultation
Website: http://seventransistorlabs.com
wrote in message
news:3d5dd5a7-fa79-41e9-b850-2dd753ff4410@googlegroups.com...
> Could some electronics guru please help ? Maybe this is a
> very silly question, so pardon me.
> In a schematic, a transformer is generally shown with 2 -3
> parallel bars in the middle to indicate the core. Often, I
> have seen the parallel bars replaced by a thick, solid bar.
> So, do the parallel bars represent a laminated core
> transformer and the thick single bar represent a ferrite
> core transformer. Any hints, suggestions would be of help.
> Thanks in advance.