Ideas how to distinguish between real transformers and coupled inductors? - Page 1
Forum section: electronics / general

author: RedLion
author_rank: Regular Contributor
timestamp: September 16, 2024, 09:36:37 am
content: So this is the first time I have a design in which there is both a transformer and a coupled inductor.This had me wondering, the symbols for "real" transformers and coupled inductors, flyback transformers, and the sorts, all usually look alike, despite the function being quite drastically different.Do you distinguish between the two in your schematics? Or just use the same symbol for both?Like many a hobbyist designer I create my own libraries as I go; I use mostly the european/german style of symbols but with some creative freedom to the symbols, so I don't mind "colouring outside the line" a little.

author: forrestc
author_rank: Unknown
timestamp: September 16, 2024, 10:06:53 am
content: Quote from: RedLion on September 16, 2024, 09:36:37 amLast I checked, a transformer is just a coupled inductor which is optimized for power transfer... or you could say that a coupled inductor is a special type of transformer. It's only when you start drilling down into the specific construction details and parameters that you notice any difference.It's kinda like the reason why a small signal fet and a giant mosfet have the same symbol. The schematic isn't intended to convey all of the parameters of every component - it's more to provide a visual illustration of how things are hooked together. And, modern schematics are starting to become not even really usable for that either due to the way many people draw modern schematics as more of a visual netlist than a real schematic.

author: Roehrenonkel
author_rank: Frequent Contributor
timestamp: September 16, 2024, 10:38:22 am
content: Hi,https://www.electronics-tutorials.ws/resources/transformer-symbols.html...first hit in my websearch.

author: RedLion
author_rank: Regular Contributor
timestamp: September 16, 2024, 03:23:02 pm
content: Quote from: forrestc on September 16, 2024, 10:06:53 amThat's my reasoning for the question too, I try to make my schematics such that you'd understand them at a first glance ideally, given a reasonable understanding of electronics.I can't stand those white blocks with net names all over, that you have to ctrl+F your way through to see what's happening.Quote from: Roehrenonkel on September 16, 2024, 10:38:22 amInteresting, not seen those before. I guess I will adapt the interrupted core for a coupled inductor to the german "black box" style symbol.Quote from: Roehrenonkel on September 16, 2024, 10:38:22 amMind you, everyone's Google results are different.

author: jonpaul
author_rank: Super Contributor
timestamp: September 16, 2024, 04:42:03 pm
content: If you are really motivated to learn about transformers and coupled inductors (actually the same thing)Suggest you buy and read:Static Electromagnetic Devices, Hunt and Stein 1963https://www.amazon.com/Static-electromagnetic-devices-William-Thomas/dp/B0007DRTW2Magnetic Components: Design and Applicationsby Steve Smith 1984https://www.amazon.com/Magnetic-Components-Applications-Steve-Smith/dp/0442203977EnjoyJon

author: RedLion
author_rank: Regular Contributor
timestamp: September 16, 2024, 06:22:40 pm
content: I'm quite familiar with the parts themselves, I was just wondering if anyone uses distinct schematic symbols for them.In my book they are sufficiently distinct that they would warrant having a different symbol.Probably I'm going to represent it with a gap in the core in the schematic symbol, that would make it different enough to see when reading a schematic, or (almost more importantly for me) when browsing the library.

author: jonpaul
author_rank: Super Contributor
timestamp: September 16, 2024, 07:39:52 pm
content: a gapped core is common in many transformers and inductors....Flyback SMPS, buck, boostno relation gappe dcore /coupled inductor...one does not imply or exclude the other.A transformer has FLUX NULL as current x turns of P = currtne x turs of S.Cuttent of tr=rsf flows in PRI and SEC simultaneously.A coupled inductor is a 2 wdg indr where current flows in only ONE wdg at a time eg flyback converters.BUT the symbos are the SAME!No schematic symbol shows a gap or lack of gap.Enjoy,Jon

author: shabaz
author_rank: Frequent Contributor
timestamp: September 16, 2024, 09:18:58 pm
content: Sometimes it's easily recognized from context, and especially when the winding start dot is on opposite ends (i.e. like top and bottom in the attachment), although that's not exactly a convention of course.I saw on a coilcraft page that they did an interesting thing where they linked two inductors at different locations on the schematic, with a dashed line.