What is this inductor symbol? - Page 1
Forum section: electronics / beginners

author: duque
author_rank: Newbie
timestamp: August 29, 2022, 01:46:15 pm
content: I am trying to figure out what type of inductor this is from the schematic and I am not finding anything that matches it online! Can someone help me?Thanks,Mike D

author: TimFox
author_rank: Super Contributor
timestamp: August 29, 2022, 01:54:02 pm
content: It is a center-tapped inductor, where each half of the inductor by itself would be 600 mH.Closing the switch changes the inductance from end to end.It is not just merely two inductances, since they appear to be tightly coupled through the ferromagnetic core.

author: golden_labels
author_rank: Super Contributor
timestamp: August 29, 2022, 02:22:46 pm
content: I believe TimFox is right, but to be sure: check if there is no second symbol like that somewhere in the same circuit. They may be sharing a single core.Presence of a phase indicator on this inductor is what makes be cautious.

author: duque
author_rank: Newbie
timestamp: August 29, 2022, 04:58:59 pm
content: Thank you for the reply. It looks like TimFox is right! Now the other weird thing I still haven't been able to find an answer for is the two solid lines with a dotted line in the middle. I can't find anywhere that verifies what type of core that is.

author: TimFox
author_rank: Super Contributor
timestamp: August 29, 2022, 05:05:12 pm
content: Sometimes, the dotted or dashed line indicates an electrostatic shield, but that would have to be connected somewhere.Other times, a dashed line indicates a non-solid core material, such as powdered iron in a binder used in RF inductors, but that also seems irrelevant here.These graphics are not standardized.

author: RoGeorge
author_rank: Super Contributor
timestamp: August 29, 2022, 06:25:57 pm
content: I don't know the English name, but I remember a similar trick used to replace a triac (the circuit was called magnetic amplifier in that old schematic, but Wikipedia shows something slightly different for "magnetic amplifier").The idea in that old article was to use transformers in series with a load, as switches (because triacs/thiristors were rare/expensive back then). The load was 220Vac light bulbs in series with 220Vac transformers, and in order to turn on the light bulb, a low voltage (transistor) was shorting the secondary of the transformer. When a transformer is shorted, the current rises through its primary coil series with the load, too. Same with auto-transformers (as in the OP cropped schematic).A larger schematic, or the destination of that schematic/device might be helpful to guess correctly.Otherwise, that symbol is probably an auto-transformer (which is a dual 600mH inductance coiled on the same magnetic core).My guess is the 2x600 mH is used as a magnetic (amplifier) switch, in a similar manner as explained before. Some load is in series, and when one half of the coil is shorted, the series load will get AC current.

author: KT88
author_rank: Frequent Contributor
timestamp: August 29, 2022, 10:46:18 pm
content: QuoteThat would be a "Transductor".It is an auto-transformer that would be come low impedance or short when one half of it gets shorted. that could make sense as a soft-start circuit...CheersAndreas

author: duque
author_rank: Newbie
timestamp: August 31, 2022, 10:31:01 am
content: This is a 9VDC circuit. I found the contact for the guy that created this schematic. Hopefully I can talk to him today.

author: Benta
author_rank: Super Contributor
timestamp: August 31, 2022, 04:06:22 pm
content: My guess is tha the solid/dashed core symbol means it's a laminated core for AC signals (as opposed to, eg, a DC solenoid).

author: rooppoorali
author_rank: Regular Contributor
timestamp: September 01, 2022, 10:51:11 am
content: I'd like to know too. Looks confusing. I can see some lists of inductors like this and many more:https://www.pinterest.com/pin/566749934336366493/?nic_v3=1a3TBRf2vBut could not find a single symbol which matches your mentioned one.

author: duque
author_rank: Newbie
timestamp: September 01, 2022, 03:26:08 pm
content: Well I thought I had the contact for the guy that created the schematic.. Looks like there was an updated schematic made by the manufacturing factory in China which is what I have. It looks like we have to conclude for now at least that this is just a non standard symbol like TimFox said.Thanks for the help!Mike D

author: MrAl
author_rank: Super Contributor
timestamp: September 01, 2022, 09:25:26 pm
content: Quote from: duque on September 01, 2022, 03:26:08 pmIn order to figure out what it does we have to see the entire schematic.That's the only way now.