interesting inductor

https://www.digikey.com/products/en?keywords=RN%20242-6-02-1M8

That is technically a commmon-mode choke - which makes it cheap - but
is probably useful for a real-inductor need that we have now.

It's spec'd at 1.8 mH per winding, but my AADE meter says about 2.5. I
should measure it some other ways to be sure.

(K seems to be over 0.99, so it would be a good common-mode filter but
not good for diff mode noise.)

I want an inductive DAC, namely a series of steps of inductance made
from inductors and relays. One of these could get me 2.5 uH, or 10 uH
with the windings in series. Two of the same part gives 0, 2.5, 5, 10,
and 20 mH, plus the oddball 12.5.

With 3 amps DC on both windings in series, it didn't get detectably
warm.

What I need to do, or actually delegate, is to measure L better, and
then L vs current. Need to hack up some rigs to do that.

Nice small PCB footprint. I can envision using this as a real
transformer, in power applications.

 

On Sat, 17 Aug 2019 18:16:30 +0100, Clive Arthur
<cliveta@nowaytoday.co.uk> wrote:

On 17/08/2019 17:31, jlarkin@highlandsniptechnology.com wrote:

https://www.digikey.com/products/en?keywords=RN%20242-6-02-1M8

That is technically a commmon-mode choke - which makes it cheap - but
is probably useful for a real-inductor need that we have now.

It's spec'd at 1.8 mH per winding, but my AADE meter says about 2.5. I
should measure it some other ways to be sure.

(K seems to be over 0.99, so it would be a good common-mode filter but
not good for diff mode noise.)

I want an inductive DAC, namely a series of steps of inductance made
from inductors and relays. One of these could get me 2.5 uH, or 10 uH
with the windings in series. Two of the same part gives 0, 2.5, 5, 10,
and 20 mH, plus the oddball 12.5.

With 3 amps DC on both windings in series, it didn't get detectably
warm.

But it would be saturated, surely?

We'll have to find out. In a common-mode filter, I guess that they
assume that the line currents cancel in the core.


dot
L1------/////////-------> load

L2------/////////-------<
dot

What I need to do, or actually delegate, is to measure L better, and
then L vs current. Need to hack up some rigs to do that.

Nice small PCB footprint. I can envision using this as a real
transformer, in power applications.


Cheers

 

On Sat, 17 Aug 2019 17:08:04 GMT, Jan Panteltje
<pNaOnStPeAlMtje@yahoo.com> wrote:

On a sunny day (Sat, 17 Aug 2019 09:31:05 -0700) it happened
jlarkin@highlandsniptechnology.com wrote in
gf9gledtl3dk47eah278d6ohr2211bpl7q@4ax.com>:


https://www.digikey.com/products/en?keywords=RN%20242-6-02-1M8

That is technically a commmon-mode choke - which makes it cheap - but
is probably useful for a real-inductor need that we have now.

It's spec'd at 1.8 mH per winding, but my AADE meter says about 2.5. I
should measure it some other ways to be sure.

(K seems to be over 0.99, so it would be a good common-mode filter but
not good for diff mode noise.)

I want an inductive DAC, namely a series of steps of inductance made
from inductors and relays. One of these could get me 2.5 uH, or 10 uH
with the windings in series. Two of the same part gives 0, 2.5, 5, 10,
and 20 mH, plus the oddball 12.5.

I did that once for tuning a 30 kHz to 150 kHz or there about inductive loop driver,
Watch your voltages when the relays switch,

I will have a uP controlling everything, so I can kill the source when
the relays switch. Cold switch.

>I wound the coils on potcores myself.

Yuk. I hate to wind coils.

Sometimes I have to.

https://www.dropbox.com/s/o2hz6oi08agzdy8/T850_Inductor.JPG?raw=1

Toroids are worse. I'm thinking that the Schaffner part is a ferrite
toroid.

Schaffner is a very old company, already used their stuff in the sixties.
10 weeks lead time?

Stock at Digikey.

 

[Clive Arthur]

On 17/08/2019 17:31, jlarkin@highlandsniptechnology.com wrote:

https://www.digikey.com/products/en?keywords=RN%20242-6-02-1M8

That is technically a commmon-mode choke - which makes it cheap - but
is probably useful for a real-inductor need that we have now.

It's spec'd at 1.8 mH per winding, but my AADE meter says about 2.5. I
should measure it some other ways to be sure.

(K seems to be over 0.99, so it would be a good common-mode filter but
not good for diff mode noise.)

I want an inductive DAC, namely a series of steps of inductance made
from inductors and relays. One of these could get me 2.5 uH, or 10 uH
with the windings in series. Two of the same part gives 0, 2.5, 5, 10,
and 20 mH, plus the oddball 12.5.

With 3 amps DC on both windings in series, it didn't get detectably
warm.

But it would be saturated, surely?

What I need to do, or actually delegate, is to measure L better, and
then L vs current. Need to hack up some rigs to do that.

Nice small PCB footprint. I can envision using this as a real
transformer, in power applications.

Cheers
--
Clive

 

[Jan Panteltje]

On a sunny day (Sat, 17 Aug 2019 09:31:05 -0700) it happened
jlarkin@highlandsniptechnology.com wrote in
<gf9gledtl3dk47eah278d6ohr2211bpl7q@4ax.com>:

https://www.digikey.com/products/en?keywords=RN%20242-6-02-1M8

That is technically a commmon-mode choke - which makes it cheap - but
is probably useful for a real-inductor need that we have now.

It's spec'd at 1.8 mH per winding, but my AADE meter says about 2.5. I
should measure it some other ways to be sure.

(K seems to be over 0.99, so it would be a good common-mode filter but
not good for diff mode noise.)

I want an inductive DAC, namely a series of steps of inductance made
from inductors and relays. One of these could get me 2.5 uH, or 10 uH
with the windings in series. Two of the same part gives 0, 2.5, 5, 10,
and 20 mH, plus the oddball 12.5.

I did that once for tuning a 30 kHz to 150 kHz or there about inductive loop driver,
Watch your voltages when the relays switch,
I wound the coils on potcores myself.

Schaffner is a very old company, already used their stuff in the sixties.
10 weeks lead time?

 

[Tim Williams]

jlarkin@highlandsniptechnology.com> wrote in message
news:gf9gledtl3dk47eah278d6ohr2211bpl7q@4ax.com...

I want an inductive DAC, namely a series of steps of inductance made
from inductors and relays. One of these could get me 2.5 uH, or 10 uH
with the windings in series. Two of the same part gives 0, 2.5, 5, 10,
and 20 mH, plus the oddball 12.5.

At what saturation current? Q? Tolerance?

With 3 amps DC on both windings in series, it didn't get detectably
warm.

Good luck keeping 2.5mH at that current in anti-series.

The 2.5mH alone varies widely with ACV and manufacture. Buy a dozen from
different distributors and see if they measure the same.

Ungapped ferrite is the Z5U of magnetics.

CMCs typically saturate in the 10s of mA.

I don't have one of these handy to measure. I have looked at the family
before, and they have reasonable cost, and attenuation for EMC purposes,
particularly at higher frequencies.

What I need to do, or actually delegate, is to measure L better, and
then L vs current. Need to hack up some rigs to do that.

Nice small PCB footprint. I can envision using this as a real
transformer, in power applications.

Yes, CMCs are actually transformers, not coupled inductors. Their leakage
may not be great, but the isolation ratings are exemplary, making them
tempting for such purposes as DC-DC converters. It's hard to get more than
a watt or so through them, however.

Tim

--
Seven Transistor Labs, LLC
Electrical Engineering Consultation and Design
Website: https://www.seventransistorlabs.com/

 

On Sat, 17 Aug 2019 12:31:46 -0500, "Tim Williams"
<tiwill@seventransistorlabs.com> wrote:

jlarkin@highlandsniptechnology.com> wrote in message
news:gf9gledtl3dk47eah278d6ohr2211bpl7q@4ax.com...
I want an inductive DAC, namely a series of steps of inductance made
from inductors and relays. One of these could get me 2.5 uH, or 10 uH
with the windings in series. Two of the same part gives 0, 2.5, 5, 10,
and 20 mH, plus the oddball 12.5.

At what saturation current? Q? Tolerance?

I might want to output as much as 3 amps RMS. This will be a 3-phase
AC source, actually a PM alternator simulator with programmable
resistance and inductance. High inductances will be DSP simulated, but
I want some real L to be there for high frequencies. Maybe just one
real inductor would do. It's a messy simulation.

With 3 amps DC on both windings in series, it didn't get detectably
warm.

Good luck keeping 2.5mH at that current in anti-series.

That's the hazard. We'll have to measure it. If this won't work, we'll
have to buy a bunch of klunky single inductors.

The 2.5mH alone varies widely with ACV and manufacture. Buy a dozen from
different distributors and see if they measure the same.

Ungapped ferrite is the Z5U of magnetics.

CMCs typically saturate in the 10s of mA.

It's only about 15 mohms per winding, so there can't be many turns.

I don't have one of these handy to measure. I have looked at the family
before, and they have reasonable cost, and attenuation for EMC purposes,
particularly at higher frequencies.


What I need to do, or actually delegate, is to measure L better, and
then L vs current. Need to hack up some rigs to do that.

Nice small PCB footprint. I can envision using this as a real
transformer, in power applications.

Yes, CMCs are actually transformers, not coupled inductors. Their leakage
may not be great, but the isolation ratings are exemplary, making them
tempting for such purposes as DC-DC converters. It's hard to get more than
a watt or so through them, however.

This one should be good for lots of watts. Leakage L is only 17 uH!

 

[Jan Panteltje]

On a sunny day (Sat, 17 Aug 2019 10:23:30 -0700) it happened
jlarkin@highlandsniptechnology.com wrote in
<lodgle1nsh8ovie0gm7bom5j74tadr3rhd@4ax.com>:

On Sat, 17 Aug 2019 17:08:04 GMT, Jan Panteltje
pNaOnStPeAlMtje@yahoo.com> wrote:

On a sunny day (Sat, 17 Aug 2019 09:31:05 -0700) it happened
jlarkin@highlandsniptechnology.com wrote in
gf9gledtl3dk47eah278d6ohr2211bpl7q@4ax.com>:


https://www.digikey.com/products/en?keywords=RN%20242-6-02-1M8

That is technically a commmon-mode choke - which makes it cheap - but
is probably useful for a real-inductor need that we have now.

It's spec'd at 1.8 mH per winding, but my AADE meter says about 2.5. I
should measure it some other ways to be sure.

(K seems to be over 0.99, so it would be a good common-mode filter but
not good for diff mode noise.)

I want an inductive DAC, namely a series of steps of inductance made
from inductors and relays. One of these could get me 2.5 uH, or 10 uH
with the windings in series. Two of the same part gives 0, 2.5, 5, 10,
and 20 mH, plus the oddball 12.5.

I did that once for tuning a 30 kHz to 150 kHz or there about inductive loop driver,
Watch your voltages when the relays switch,

I will have a uP controlling everything, so I can kill the source when
the relays switch. Cold switch.

OK, nice,

I wound the coils on potcores myself.

Yuk. I hate to wind coils.

No problem here, for fine wire I put it on the dremel, a thousand turns is no problem.
Counting is.

Sometimes I have to.

https://www.dropbox.com/s/o2hz6oi08agzdy8/T850_Inductor.JPG?raw=1

That circuit, I was thinking about that, is basically the same as a TV horizontal output no?
+12V
| ____
||| (_____ defection coill
)|| ------
)|| ( HV coil
||| (____
|-----------
c | |
-- b --- |
e / \ ===
| --- | 'boost' cap
| | |
/// /// ///

----- -------- base drive,
| |
--

That gives a parabolic voltage pulse during flyback,
the HV coil is tuned to IIRC (was a discussion about that here long time ago) the third harmonic.
That pulse is the output you want,
only you have a smaller coil, resulting in a higher frequency,
The energy you store into the coil while the transistor is 'on' increases the longer it is on,
and the higher then the pulse is.
I have wound my own TV transformers both for tubes and transistors.

Never understood what the problem was with your coil.

Toroids are worse. I'm thinking that the Schaffner part is a ferrite
toroid.

I dunno, I used their thyristor driver pulse transformers, also 4 kV isolation tested.
Nice stuff.

Schaffner is a very old company, already used their stuff in the sixties.
10 weeks lead time?

Stock at Digikey.

 

[Tim Williams]

<jlarkin@highlandsniptechnology.com> wrote in message
news:tieglep6bf2ktbrifpk4nm43n3hddmjmkd@4ax.com...

It's hard to get more than
a watt or so through them, however.

This one should be good for lots of watts. Leakage L is only 17 uH!

Yes, that's the point.

Would be alright for some watts as a resonant transformer, but you still
need secondary side regulation for each output channel; no improvement over
a bunch of discrete DC-DC modules.

Tim

--
Seven Transistor Labs, LLC
Electrical Engineering Consultation and Design
Website: https://www.seventransistorlabs.com/

 

On Sat, 17 Aug 2019 19:39:07 GMT, Jan Panteltje
<pNaOnStPeAlMtje@yahoo.com> wrote:

On a sunny day (Sat, 17 Aug 2019 10:23:30 -0700) it happened
jlarkin@highlandsniptechnology.com wrote in
lodgle1nsh8ovie0gm7bom5j74tadr3rhd@4ax.com>:

On Sat, 17 Aug 2019 17:08:04 GMT, Jan Panteltje
pNaOnStPeAlMtje@yahoo.com> wrote:

On a sunny day (Sat, 17 Aug 2019 09:31:05 -0700) it happened
jlarkin@highlandsniptechnology.com wrote in
gf9gledtl3dk47eah278d6ohr2211bpl7q@4ax.com>:


https://www.digikey.com/products/en?keywords=RN%20242-6-02-1M8

That is technically a commmon-mode choke - which makes it cheap - but
is probably useful for a real-inductor need that we have now.

It's spec'd at 1.8 mH per winding, but my AADE meter says about 2.5. I
should measure it some other ways to be sure.

(K seems to be over 0.99, so it would be a good common-mode filter but
not good for diff mode noise.)

I want an inductive DAC, namely a series of steps of inductance made
from inductors and relays. One of these could get me 2.5 uH, or 10 uH
with the windings in series. Two of the same part gives 0, 2.5, 5, 10,
and 20 mH, plus the oddball 12.5.

I did that once for tuning a 30 kHz to 150 kHz or there about inductive loop driver,
Watch your voltages when the relays switch,

I will have a uP controlling everything, so I can kill the source when
the relays switch. Cold switch.

OK, nice,


I wound the coils on potcores myself.

Yuk. I hate to wind coils.

No problem here, for fine wire I put it on the dremel, a thousand turns is no problem.
Counting is.

My Dremel won't wind toroids! There is one trick for hand winding
toroids, where you make an H-shaped wire storage thing out of FR4 and
keep passing it through the hole, doling out wire. That helps a
little.

Sometimes I have to.

https://www.dropbox.com/s/o2hz6oi08agzdy8/T850_Inductor.JPG?raw=1


That circuit, I was thinking about that, is basically the same as a TV horizontal output no?
+12V
| ____
||| (_____ defection coill
)|| ------
)|| ( HV coil
||| (____
|-----------
c | |
-- b --- |
e / \ ===
| --- | 'boost' cap
| | |
/// /// ///

----- -------- base drive,
| |
--

That gives a parabolic voltage pulse during flyback,
the HV coil is tuned to IIRC (was a discussion about that here long time ago) the third harmonic.
That pulse is the output you want,
only you have a smaller coil, resulting in a higher frequency,
The energy you store into the coil while the transistor is 'on' increases the longer it is on,
and the higher then the pulse is.
I have wound my own TV transformers both for tubes and transistors.

No, not the same, more of a non-resonant HV pulse generator.

Never understood what the problem was with your coil.

I kept frying the inductors, two generations of Coilcraft parts. I was
well within the RMS current ratings, but skin effect apparently
dominated and the coils smoked.

The clever horizontal output thing was originally tubes of course,
then bipolar transistors. I discovered that the c-b junction of one
high voltage horizontal-output transistor accidentally had the ideal
doping profile to be a kilovolt Grehkov drift step-recovery diode. Too
bad they don't make it any more.

 

On Saturday, 17 August 2019 18:31:13 UTC+2, jla...@highlandsniptechnology.com wrote:

https://www.digikey.com/products/en?keywords=RN%20242-6-02-1M8

That is technically a commmon-mode choke - which makes it cheap - but
is probably useful for a real-inductor need that we have now.

It's spec'd at 1.8 mH per winding, but my AADE meter says about 2.5. I
should measure it some other ways to be sure.

(K seems to be over 0.99, so it would be a good common-mode filter but
not good for diff mode noise.)

I want an inductive DAC, namely a series of steps of inductance made
from inductors and relays. One of these could get me 2.5 uH, or 10 uH
with the windings in series. Two of the same part gives 0, 2.5, 5, 10,
and 20 mH, plus the oddball 12.5.

With 3 amps DC on both windings in series, it didn't get detectably
warm.

That's because the series connection is the line current, so you only have differential inductance, probably 100 times lower than the common mode inductance of 1.8mH

The common mode inductance of 1.8mH saturates in the mA region

Cheers

Klaus

 

On Sat, 17 Aug 2019 13:57:55 -0700 (PDT), klaus.kragelund@gmail.com
wrote:

On Saturday, 17 August 2019 18:31:13 UTC+2, jla...@highlandsniptechnology.com wrote:
https://www.digikey.com/products/en?keywords=RN%20242-6-02-1M8

That is technically a commmon-mode choke - which makes it cheap - but
is probably useful for a real-inductor need that we have now.

It's spec'd at 1.8 mH per winding, but my AADE meter says about 2.5. I
should measure it some other ways to be sure.

(K seems to be over 0.99, so it would be a good common-mode filter but
not good for diff mode noise.)

I want an inductive DAC, namely a series of steps of inductance made
from inductors and relays. One of these could get me 2.5 uH, or 10 uH
with the windings in series. Two of the same part gives 0, 2.5, 5, 10,
and 20 mH, plus the oddball 12.5.

With 3 amps DC on both windings in series, it didn't get detectably
warm.


That's because the series connection is the line current, so you only have differential inductance, probably 100 times lower than the common mode inductance of 1.8mH

The common mode inductance of 1.8mH saturates in the mA region

Cheers

Klaus

A thing that size should store a few mJ.

 

[Tim Williams]

<jlarkin@highlandsniptechnology.com> wrote in message
newsstgle10i89vaq9ful835u5u68hk71dbto@4ax.com...

A thing that size should store a few mJ.

A few uJ at best.

Look, I get it, you don't work with these things on a daily basis. But you
are still aware that saturation is a thing, right..?

Tim

--
Seven Transistor Labs, LLC
Electrical Engineering Consultation and Design
Website: https://www.seventransistorlabs.com/

 

On Sat, 17 Aug 2019 17:34:15 -0500, "Tim Williams"
<tiwill@seventransistorlabs.com> wrote:

jlarkin@highlandsniptechnology.com> wrote in message
newsstgle10i89vaq9ful835u5u68hk71dbto@4ax.com...
A thing that size should store a few mJ.


A few uJ at best.

Look, I get it, you don't work with these things on a daily basis. But you
are still aware that saturation is a thing, right..?

Tim

This is probably about the same size core as what's inside the CM
choke:

https://www.mouser.com/ProductDetail/JW-Miller/2324-V-RC?qs=sGAEpiMZZMsg%252By3WlYCkU4M2TElYYSkELQ4ZU27m%252Bck%3D

That's 1 mH, rated 2.4 amps, stores about 1.7 mJ at rated current.


You can store a few uJ in a really tiny inductor.

https://www.mouser.com/ProductDetail/KEMET/L1210R1R0MDWIT?qs=sGAEpiMZZMsg%252By3WlYCkUyI47vaDA87SCPoQ72WSmes%3D

 

[Tim Williams]

<jlarkin@highlandsniptechnology.com> wrote in message
news:361hleth37djaaoh8ka2ekj5oth9hv28fd@4ax.com...

This is probably about the same size core as what's inside the CM
choke:

https://www.mouser.com/ProductDetail/JW-Miller/2324-V-RC?qs=sGAEpiMZZMsg%252By3WlYCkU4M2TElYYSkELQ4ZU27m%252Bck%3D

That's 1 mH, rated 2.4 amps, stores about 1.7 mJ at rated current.

So what, you think they put the same core in that CMC?

Tim

--
Seven Transistor Labs, LLC
Electrical Engineering Consultation and Design
Website: https://www.seventransistorlabs.com/

 

[Bill Sloman]

On Sunday, August 18, 2019 at 3:23:38 AM UTC+10, jla...@highlandsniptechnology.com wrote:

On Sat, 17 Aug 2019 17:08:04 GMT, Jan Panteltje
pNaOnStPeAlMtje@yahoo.com> wrote:

On a sunny day (Sat, 17 Aug 2019 09:31:05 -0700) it happened
jlarkin@highlandsniptechnology.com wrote in
gf9gledtl3dk47eah278d6ohr2211bpl7q@4ax.com>:

<snip>

Toroids are worse. I'm thinking that the Schaffner part is a ferrite
toroid.

Toroid winding machines are cute. They depend on a split bobbin (two semicircular halves) which you put together so it goes through the hole in the torpid. You then wind the length of wire you need onto the bobbin, then wind it off again onto the toroid.

Elegant, but a pig to automate.

<snip>

--
Bill Sloman, Sydney

 

On Sat, 17 Aug 2019 20:09:20 -0500, "Tim Williams"
<tiwill@seventransistorlabs.com> wrote:

jlarkin@highlandsniptechnology.com> wrote in message
news:361hleth37djaaoh8ka2ekj5oth9hv28fd@4ax.com...
This is probably about the same size core as what's inside the CM
choke:

https://www.mouser.com/ProductDetail/JW-Miller/2324-V-RC?qs=sGAEpiMZZMsg%252By3WlYCkU4M2TElYYSkELQ4ZU27m%252Bck%3D

That's 1 mH, rated 2.4 amps, stores about 1.7 mJ at rated current.


So what, you think they put the same core in that CMC?

Tim

Ferrites store similar energy by volume.

Millijoules, not microjoules.

You snipped your "few microjoules" claim. We'll just forget you ever
said that.

 

[Tim Williams]

<jlarkin@highlandsniptechnology.com> wrote in message
newsddhlehu5jglvajkkt65p5pg55k1qpkdg7@4ax.com...
> Ferrites store similar energy by volume.

When gapped, yes.

Millijoules, not microjoules.

You snipped your "few microjoules" claim. We'll just forget you ever
said that.

A mu_eff about 1000 times higher than the powdered iron core is both very
likely for the choke, and fully accounts for the 1000 times lower energy
rating.

Capacitors go as epsilon E^2 / 2, but high-k dielectrics have considerably
lower Emax so store about the same energy (give or take how much you want to
saturate them in the process).

Inductors go as B^2 / (2 mu), so a mu=10k core stores fuck-all energy at
saturation.

Tim

--
Seven Transistor Labs, LLC
Electrical Engineering Consultation and Design
Website: https://www.seventransistorlabs.com/

 

On Sat, 17 Aug 2019 22:31:26 -0500, "Tim Williams"
<tiwill@seventransistorlabs.com> wrote:

jlarkin@highlandsniptechnology.com> wrote in message
newsddhlehu5jglvajkkt65p5pg55k1qpkdg7@4ax.com...
Ferrites store similar energy by volume.

When gapped, yes.


Millijoules, not microjoules.

You snipped your "few microjoules" claim. We'll just forget you ever
said that.

A mu_eff about 1000 times higher than the powdered iron core is both very
likely for the choke, and fully accounts for the 1000 times lower energy
rating.

Capacitors go as epsilon E^2 / 2, but high-k dielectrics have considerably
lower Emax so store about the same energy (give or take how much you want to
saturate them in the process).

Inductors go as B^2 / (2 mu), so a mu=10k core stores fuck-all energy at
saturation.

Tim

The estimate of a few mA to saturate this core corresponds to ballpark
10 nJ storage capacity.

 

[Jan Panteltje]

On a sunny day (Sat, 17 Aug 2019 21:17:26 -0700) it happened
jlarkin@highlandsniptechnology.com wrote in
<j7khle9q5rsj7ld0iblliphov3o2a83pj2@4ax.com>:

On Sat, 17 Aug 2019 22:31:26 -0500, "Tim Williams"
tiwill@seventransistorlabs.com> wrote:

jlarkin@highlandsniptechnology.com> wrote in message
newsddhlehu5jglvajkkt65p5pg55k1qpkdg7@4ax.com...
Ferrites store similar energy by volume.

When gapped, yes.


Millijoules, not microjoules.

You snipped your "few microjoules" claim. We'll just forget you ever
said that.

A mu_eff about 1000 times higher than the powdered iron core is both very
likely for the choke, and fully accounts for the 1000 times lower energy
rating.

Capacitors go as epsilon E^2 / 2, but high-k dielectrics have considerably
lower Emax so store about the same energy (give or take how much you want to
saturate them in the process).

Inductors go as B^2 / (2 mu), so a mu=10k core stores fuck-all energy at
saturation.

Tim

The estimate of a few mA to saturate this core corresponds to ballpark
10 nJ storage capacity.

John,
Tim may have a good point,
long ago I dissasembled (bought a load for 1 dollar or so on ebay)
one of those coils,
http://panteltje.com/pub/mains_filter_coils_disssasembled_IMG_0149.JPG
core is very tiny.
Only one half shown here other is missing.