Proper terminology/classifications for inductors? - Page 1
Forum section: electronics / beginners

author: hirada
author_rank: Regular Contributor
timestamp: March 08, 2022, 08:43:08 pm
content: Not really technical, more of a bit of a language thing here, as I am finally trying to catalogize my parts in a hierarchical manner. For transistors or capacitors it is easy. You have the genre at top, f.e. transistor, then you have pnp, nJFET, Darlington, UJT.. you name it. Same for capacitors. Below those that we have caramic, foil, electrolytic.. and those may further be broken down as well.Now for the magnetic stuff, trying to avoid the same label for different levels of the hierachy to make subsequent searches easier.Would that be coil -> inductor/choke.. or rather inductor at top level followed by coil or choke one level below? Or maybe no coil at all, but rather inductor -> choke, fixed...Any other terms I may not have thought of? What would be the proper top designator/identifier for this class of parts? Browsing mouser did not really help here, as they use multiple terms as well, contrary to f.e. resistors or capacitors.Thanks for sharing your way of (possibly) doing it

author: TimFox
author_rank: Super Contributor
timestamp: March 08, 2022, 08:48:17 pm
content: Well, as an electronic basic object, an "inductor" is a component whose main attribute is its inductance.A "coil" is the usual way to make an inductor, but there are other possible geometries such as a "hairpin". Normally, one does not use the term "coil" to order an inductor, but the term is common usage. I believe that "coil" is usually used to denote an inductor in a resonant circuit, such as an RF tuning circuit.A "choke" is a specific application of an inductor, usually one where there is a substantial DC or low-frequency current along with the high-frequency current. This is commonly used to reduce the AC current, as in a power-supply filter or an EMI filter.

author: Benta
author_rank: Super Contributor
timestamp: March 08, 2022, 09:05:14 pm
content: I'd say top level is "inductor", like "capacitor".But the next level is almost impossible, given the multitude of types and also the fact that perhaps 2/3 of inductors are custom made for their purpose.

author: hirada
author_rank: Regular Contributor
timestamp: March 09, 2022, 06:46:41 am
content: Interesting, that some wound (or hairpinned) wire seems to be so much more complicated than the other stuff. So I guess I'll have to make something up, then. Thanks very much for your help

author: T3sl4co1l
author_rank: Super Contributor
timestamp: March 09, 2022, 03:21:35 pm
content: I'd put them all under class "magnetics", types "inductor", "coupled inductor", "ferrite bead", "transformer", etc.Note that several parts overlap by contextual use:- A common-mode choke is a transformer being used sideways. Like a choke, its purpose is to "choke" off AC current, but unlike a 2-terminal part that may have to handle DC current, the CMC balances bias between the two windings, greatly shrinking its size.- A transformer is a multi-winding component which presents minimal loading to applied (AC) voltage, thus transforming the ratio of voltage/current between its windings (and isolating them at DC).- A coupled inductor, is a transformer which does load the applied voltage notably, for purposes of energy storage. Put otherwise: an inductor (likewise: a choke meant for energy storage) with multiple windings.- A ferrite bead is a choke, usually of fairly small value (few uH?), having significant losses (max Q might be <10, with Q <= 1 over a range of RF frequencies), and a modest peak impedance (some kohms in the 10-100s MHz range). They typically saturate easily with DC bias, so are mainly suitable for filtering and damping signal lines, and filtering only modest power supplies/loads (10-100s mA DC).Not all of these are in common/consistent use; for example, a "flyback transformer" has significant energy storage, making it a coupled inductor. So we should distinguish between common names (like this) and technical descriptors (like the above). More broadly, in colloquial use, a "transformer" is anything with multiple windings.There are further types or subtypes, like swinging choke, saturable reactor, magamp, etc., which aren't seen very often these days. If you just need a category for these, "Other" or "Specialty" would be fine.Also if you do much with radios, "IF Transformer" might be useful. (These are actually coupled inductors, where the coupling factor also is a tuning parameter, and they typically come equipped with tuning capacitors. They can be perhaps better described in terms of center frequency, winding impedances, bandwidth, and tapping ratios if applicable.)Tim

author: tszaboo
author_rank: Super Contributor
timestamp: March 09, 2022, 10:11:11 pm
content: Top level is definitely "magnetics".If you are interested about the classification and use cases of the parts, there is a good book, Trilogy of Magnetics from Würth. Its half explanation, half reference guide for their parts, but the info in it is great.

author: Benta
author_rank: Super Contributor
timestamp: March 09, 2022, 10:28:20 pm
content: So Neodymium magnets are now electronic components?

author: T3sl4co1l
author_rank: Super Contributor
timestamp: March 09, 2022, 11:11:26 pm
content: Quote from: Benta on March 09, 2022, 10:28:20 pmSure, why not?If you want to have additional categories for hardware, mechanical, etc., you're welcome to. You may have to abandon a strict hierarchical tree, though. Perhaps an open table of tagged items. Is a solder-in or press-fit nut mechanical or electrical? Clearly the answer must be "yes".Tim