Re: mounting a pot core

From	john larkin <jl@glen--canyon.com>
Newsgroups	sci.electronics.design
Subject	Re: mounting a pot core
Date	2026-01-26 10:58 -0800
Organization	Highland Technology
Message-ID	<b4efnk1t2b4sq40krvq584kp76ju7tkigc@4ax.com> (permalink)
References	(5 earlier) <qvndnk90ibbc3f4q8b7cg5ucp31ipr2s1l@4ax.com> <9d3fnk9uo3ebfhkmplfq0m2sv2p76vhq51@4ax.com> <10l856l$2kqo2$2@dont-email.me> <bd6fnktm5v3jrofi40qohe9oveaute4s5g@4ax.com> <4d242cc6-ed44-c919-6863-5b711e5703a1@electrooptical.net>

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On Mon, 26 Jan 2026 13:12:21 -0500, Phil Hobbs
<pcdhSpamMeSenseless@electrooptical.net> wrote:

>On 2026-01-26 11:48, john larkin wrote:
>> On Tue, 27 Jan 2026 03:36:36 +1100, Bill Sloman <bill.sloman@ieee.org>
>> wrote:
>> 
>>> On 27/01/2026 2:53 am, john larkin wrote:
>>>> On Sun, 25 Jan 2026 22:44:02 -0500, legg <legg@nospam.magma.ca> wrote:
>>>>
>>>>> On Sun, 25 Jan 2026 08:08:48 -0800, john larkin <jl@glen--canyon.com>
>>>>> wrote:
>>>>>
>>>>>> On Sun, 25 Jan 2026 08:51:24 -0500, legg <legg@nospam.magma.ca> wrote:
>>>>>>
>>>>>>> On Sat, 24 Jan 2026 19:25:35 +0000, liz@poppyrecords.invalid.invalid
>>>>>>> (Liz Tuddenham) wrote:
>>>>>>>
>>>>> <snip>
>>>>>>> In applications where power levels are important, pot core orientation
>>>>>>> will affect 'N' in the flux density concentration, and produce early
>>>>>>> saturation at the location where minimum x-sectional area occurs.
>>>>>>>
>>>>>>> RL
>>>>>>
>>>>>> That should have a small effect on my pulser. Ill try it.
>>>>>>
>>>>>> I got a 2% change in inductance when I rotated the core halves.
>>>>>>
>>>>>>
>>>>>> John Larkin
>>>>>> Highland Tech Glen Canyon Design Center
>>>>>> Lunatic Fringe Electronics
>>>>>
>>>>> 2% FREE x-sectional area, and an indication that the previous
>>>>> misalignment doesn't dominate minimum value.
>>>>>
>>>>> Mind you, you can get a similar change just by forcing out
>>>>> the fluff and detritus present at the contacting surfaces.
>>>>> That might be what you're actually seeing, even if the core
>>>>> is gapped.
>>>>>
>>>>> In pot cores, minimum x-section usually occurs where the centre
>>>>> core meets the top and bottom plates. In parts shapes designed
>>>>> for power applications, this is usually corrected.
>>>>>
>>>>> This core rotation can be used as a tolerance trim, where
>>>>> needed, but anything like that before impregnation is probably
>>>>> just biting fart bubbles.
>>>>
>>>> Impregnation?
>>>
>>> Some people like to lock the windings and the leads in place with a
>>> heavy layer of encapsulant. This works better if you put the part to
>>> encapsulated under vacuum before you pour on the encapsulant.
>>>
>>> I've never seen it done, but I've heard about it. It's apparently very
>>> messy.
>> 
>> Wet stuff is messy, really nasty in production. In the case of a
>> txline transformer made with a few turns of coax, there's no reason to
>> pot it.
>> 
>> We just spin a few turns on a bobbin and clamp it into the pot core.
>> If it got sloppy, a tie-wrap would secure things.
>> 
>> Some people like the idea of potting things. Weird.
>
>Last year we did a TDR that had to survive being pounded into hardpan 
>with a slide hammer (>20k gees).  Potting was the right answer there!
>
>We put in small bits of foam sticky tape to keep the epoxy from trashing 
>the pulse shapes.  If we did it again, we'd probably go to a six-layer 
>board and use stripline to avoid the problem (mostly).
>
>Cheers
>
>Phil Hobbs

Hard-cure epoxy can crush and destroy parts too. And, I've heard,
wreck opamp offsets.

JLC does cheap 6-layers.


John Larkin
Highland Tech Glen Canyon Design Center
Lunatic Fringe Electronics

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Thread

mounting a pot core john larkin <jl@glen--canyon.com> - 2026-01-21 08:45 -0800
  Re: mounting a pot core Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net> - 2026-01-21 12:28 -0500
  Re: mounting a pot core Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net> - 2026-01-21 12:28 -0500
    Re: mounting a pot core john larkin <jl@glen--canyon.com> - 2026-01-21 10:11 -0800
  Re: mounting a pot core Bill Sloman <bill.sloman@ieee.org> - 2026-01-22 04:49 +1100
    Re: mounting a pot core john larkin <jl@glen--canyon.com> - 2026-01-21 10:18 -0800
      Re: mounting a pot core Jeroen Belleman <jeroen@nospam.please> - 2026-01-21 23:47 +0100
        Re: mounting a pot core john larkin <jl@glen--canyon.com> - 2026-01-21 16:34 -0800
          Re: mounting a pot core Joe Gwinn <joegwinn@comcast.net> - 2026-01-21 19:48 -0500
            Re: mounting a pot core john larkin <jl@glen--canyon.com> - 2026-01-21 17:06 -0800
            Re: mounting a pot core Jeroen Belleman <jeroen@nospam.please> - 2026-01-22 13:17 +0100
              Re: mounting a pot core Joe Gwinn <joegwinn@comcast.net> - 2026-01-22 12:47 -0500
                Re: mounting a pot core Joe Gwinn <joegwinn@comcast.net> - 2026-01-22 15:49 -0500
                Re: mounting a pot core Jeroen Belleman <jeroen@nospam.please> - 2026-01-22 23:49 +0100
          Re: mounting a pot core Bill Sloman <bill.sloman@ieee.org> - 2026-01-22 17:57 +1100
            Re: mounting a pot core john larkin <jl@glen--canyon.com> - 2026-01-22 08:31 -0800
              Re: mounting a pot core Bill Sloman <bill.sloman@ieee.org> - 2026-01-23 15:57 +1100
                Re: mounting a pot core john larkin <jl@glen--canyon.com> - 2026-01-23 06:24 -0800
                Re: mounting a pot core Bill Sloman <bill.sloman@ieee.org> - 2026-01-24 03:35 +1100
                Re: mounting a pot core john larkin <jl@glen--canyon.com> - 2026-01-23 08:40 -0800
                Re: mounting a pot core Bill Sloman <bill.sloman@ieee.org> - 2026-01-24 17:01 +1100
          Re: mounting a pot core Jeroen Belleman <jeroen@nospam.please> - 2026-01-22 12:59 +0100
          Re: mounting a pot core legg <legg@nospam.magma.ca> - 2026-01-22 10:58 -0500
            Re: mounting a pot core john larkin <jl@glen--canyon.com> - 2026-01-22 10:57 -0800
              Re: mounting a pot core Bill Sloman <bill.sloman@ieee.org> - 2026-01-23 16:01 +1100
                Re: mounting a pot core john larkin <jl@glen--canyon.com> - 2026-01-23 06:19 -0800
                Re: mounting a pot core Bill Sloman <bill.sloman@ieee.org> - 2026-01-24 03:19 +1100
                Re: mounting a pot core liz@poppyrecords.invalid.invalid (Liz Tuddenham) - 2026-01-24 19:25 +0000
                Re: mounting a pot core Bill Sloman <bill.sloman@ieee.org> - 2026-01-25 14:33 +1100
                Re: mounting a pot core liz@poppyrecords.invalid.invalid (Liz Tuddenham) - 2026-01-25 11:07 +0000
                Re: mounting a pot core Bill Sloman <bill.sloman@ieee.org> - 2026-01-26 02:46 +1100
                Re: mounting a pot core legg <legg@nospam.magma.ca> - 2026-01-25 08:51 -0500
                Re: mounting a pot core john larkin <jl@glen--canyon.com> - 2026-01-25 08:08 -0800
                Re: mounting a pot core legg <legg@nospam.magma.ca> - 2026-01-25 22:44 -0500
                Re: mounting a pot core Bill Sloman <bill.sloman@ieee.org> - 2026-01-26 17:56 +1100
                Re: mounting a pot core legg <legg@nospam.magma.ca> - 2026-01-26 10:50 -0500
                Re: mounting a pot core Bill Sloman <bill.sloman@ieee.org> - 2026-01-27 03:23 +1100
                Re: mounting a pot core john larkin <jl@glen--canyon.com> - 2026-01-26 08:51 -0800
                Re: mounting a pot core john larkin <jl@glen--canyon.com> - 2026-01-26 07:53 -0800
                Re: mounting a pot core Bill Sloman <bill.sloman@ieee.org> - 2026-01-27 03:36 +1100
                Re: mounting a pot core john larkin <jl@glen--canyon.com> - 2026-01-26 08:48 -0800
                Re: mounting a pot core Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net> - 2026-01-26 13:12 -0500
                Re: mounting a pot core john larkin <jl@glen--canyon.com> - 2026-01-26 10:58 -0800
                Re: mounting a pot core Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net> - 2026-01-26 20:36 +0000
                Re: mounting a pot core Bill Sloman <bill.sloman@ieee.org> - 2026-01-27 14:30 +1100
      Re: mounting a pot core Bill Sloman <bill.sloman@ieee.org> - 2026-01-22 17:51 +1100
        Re: mounting a pot core john larkin <jl@glen--canyon.com> - 2026-01-22 11:09 -0800
          Re: mounting a pot core Bill Sloman <bill.sloman@ieee.org> - 2026-01-23 16:16 +1100
            Re: mounting a pot core john larkin <jl@glen--canyon.com> - 2026-01-23 06:13 -0800
              Re: mounting a pot core Jeroen Belleman <jeroen@nospam.please> - 2026-01-23 16:07 +0100
                Re: mounting a pot core john larkin <jl@glen--canyon.com> - 2026-01-23 08:22 -0800
                Re: mounting a pot core Jeroen Belleman <jeroen@nospam.please> - 2026-01-24 12:17 +0100
                Re: mounting a pot core john larkin <jl@glen--canyon.com> - 2026-01-24 07:54 -0800
                Re: mounting a pot core Jeroen Belleman <jeroen@nospam.please> - 2026-01-25 13:04 +0100
                Re: mounting a pot core john larkin <jl@glen--canyon.com> - 2026-01-25 07:33 -0800
                Re: mounting a pot core Jeroen Belleman <jeroen@nospam.please> - 2026-01-25 17:32 +0100
                Re: mounting a pot core john larkin <jl@glen--canyon.com> - 2026-01-25 11:12 -0800
                Re: mounting a pot core JM <sunaecoNoChoppedPork@gmail.com> - 2026-01-25 19:44 +0000
                Re: mounting a pot core john larkin <jl@glen--canyon.com> - 2026-01-25 13:07 -0800
                Re: mounting a pot core JM <sunaecoNoChoppedPork@gmail.com> - 2026-01-25 22:40 +0000
                Re: mounting a pot core john larkin <jl@glen--canyon.com> - 2026-01-25 17:29 -0800
                Re: mounting a pot core JM <sunaecoNoChoppedPork@gmail.com> - 2026-01-25 19:40 +0000
              Re: mounting a pot core Bill Sloman <bill.sloman@ieee.org> - 2026-01-24 03:39 +1100
                Re: mounting a pot core john larkin <jl@glen--canyon.com> - 2026-01-23 10:09 -0800
                Re: mounting a pot core Bill Sloman <bill.sloman@ieee.org> - 2026-01-24 16:49 +1100
  Re: mounting a pot core legg <legg@nospam.magma.ca> - 2026-01-22 10:46 -0500
    Re: mounting a pot core john larkin <jl@glen--canyon.com> - 2026-01-22 11:16 -0800

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