Unknow inductor - Page 1
Forum section: electronics / repair

author: hafrse
author_rank: Regular Contributor
timestamp: March 10, 2024, 01:28:40 pm
content: Hello,I have an inductor with of the 2 copper connection poles is broken, I need to find a replacement , please see the picture on how to decode the value of this inductor, many thanks!

author: inse
author_rank: Super Contributor
timestamp: March 10, 2024, 04:48:18 pm
content: Probably (!) this is a custom wound inductor, I can only decode so far: SH is the ferrite core manufacturer, now EPCOS, N22 is the ferrite type- the other numbers I can’t figure out.The most reasonable repair is to unwind the coil, carefully counting the turns, then rewind it with same diameter magnet wire.

author: fzabkar
author_rank: Super Contributor
timestamp: March 10, 2024, 05:07:31 pm
content: The logo belongs to Siemens.Perhaps "W25" reflects the wire size and "160" could mean 160mH?This thread looks interesting:https://www.diyaudio.com/community/threads/what-is-this-siemens-core-transformer.348685/http://bitsavers.informatik.uni-stuttgart.de/components/siemens/1983_Siemens_Ferrite_Cores_and_Hardware.pdf

author: coppercone2
author_rank: Super Contributor
timestamp: March 10, 2024, 05:20:22 pm
content: you can soak it in acetone or something an it should come apart so long you reglue with inductor safe glue (for ferrite)

author: inse
author_rank: Super Contributor
timestamp: March 10, 2024, 05:27:10 pm
content: Cooking it in water should be sufficient

author: hafrse
author_rank: Regular Contributor
timestamp: March 10, 2024, 07:03:30 pm
content: Quote from: inse on March 10, 2024, 05:27:10 pmYes, it was easy . In the picture there is another inductor (working) which I have desoldered, it measures 290mH but not sure if they are identical.

author: coppercone2
author_rank: Super Contributor
timestamp: March 10, 2024, 07:28:16 pm
content: if its just damaged mechanically you can do a splice and seal it up with some Q-dope maybe

author: inse
author_rank: Super Contributor
timestamp: March 10, 2024, 09:01:46 pm
content: As by Murphys law, it’s always the entering wire that breaks…

author: srb1954
author_rank: Super Contributor
timestamp: March 10, 2024, 09:12:34 pm
content: Quote from: hafrse on March 10, 2024, 01:28:40 pmPot cores come in standard sizes so it should be possible to narrow down the type knowing the external dimensions and the ferrite type, which might be the N22 code.The 160 code is probably the inductance factor, AL, for the core. The inductance can be calculated (reasonably accurately) as L = n2ALnH so it might be possible to determine the inductance by unwinding the bobbin and counting the turns.Pot cores sometimes also have an air gap in the centre pole to adjust the inductance factor and to allow for fine adjustment with a small core screwed into the centre hole. Does the black plug in the centre have a screwdriver adjustment or similar?

author: coppercone2
author_rank: Super Contributor
timestamp: March 10, 2024, 10:50:47 pm
content: if only the wire is just broken then just measure it

author: hafrse
author_rank: Regular Contributor
timestamp: March 11, 2024, 08:48:12 am
content: Quote from: inse on March 10, 2024, 09:01:46 pmYes, it is

author: hafrse
author_rank: Regular Contributor
timestamp: March 11, 2024, 08:51:03 am
content: Quote from: srb1954 on March 10, 2024, 09:12:34 pmYes, the small black plug is adjustable but screwdriver "part" is broken

author: inse
author_rank: Super Contributor
timestamp: March 11, 2024, 09:52:37 am
content: If you have all the pieces, you can glue them back together with superglue.If you do it right, no additional gap will be created

author: srb1954
author_rank: Super Contributor
timestamp: March 11, 2024, 10:22:24 am
content: Quote from: hafrse on March 11, 2024, 08:51:03 amSince it has an adjustor the inductor was probably required to be tuned to a fairly precise value for the circuit. The adjustors had a fairly small range of adjustment, usually less than +5% i.e. they always increased the inductance as the adjustor core was screwed in.

author: srb1954
author_rank: Super Contributor
timestamp: March 11, 2024, 10:27:36 am
content: Quote from: inse on March 11, 2024, 09:52:37 amDue to its relatively low ALvalue the pot core would have a precisely ground air gap in the centre portion of the core. It would be extremely difficult to accurately maintain this precise air gap if you were gluing a fractured core back together and you would likely get gross errors in the inductance of such a repaired pot core.

author: T3sl4co1l
author_rank: Super Contributor
timestamp: March 11, 2024, 01:42:57 pm
content: 160 could be the A_L in nH. Pot cores are popular (or, were, when inductors in audio filters etc. were the way to be) for reasonably-high-Q, moderately adjustable, custom/precision values. The hole in the center can be used for mounting, or as I think in this case, a ferrite slug/screw can be placed there to adjust the air gap, which is normally ground in the center (center peg(s) ground down below the outer limbs) and therefore a slug down the middle acts to reduce the air gap, depending on depth of insertion.You'd have to know how to tune/align the surrounding circuit to replace the part.Tim

author: inse
author_rank: Super Contributor
timestamp: March 11, 2024, 02:53:40 pm
content: Whats the application anyway?

author: pope
author_rank: Frequent Contributor
timestamp: March 11, 2024, 03:02:47 pm
content: Is this from an EQ? Ia so, can you not measure the capacitor value and figure out the L of the inductor? As long as you know the frequency point that is...