Its probably too much to hope that I can find any actual data, or for that
matter there's any standard for colour coding.

Does anyone have any generic info on typical properties of this type of
core?

TIA.

You mean the ugly yellow and white ones? Powdered iron, I think mix 23 or
27 or somesuch. Amazingly, I think most manufacturers actually follow this
coloring.

Lossy as hell, so put on a lot of turns, keep AC voltage low, and ripple
current even lower. Otherwise, use a fan.

Typical sizes are around 130 nH/T^2, and saturation at maybe 500 At.

Tim

--
Deep Friar: a very philosophical monk.
Website: http://webpages.charter.net/dawill/tmoranwms

"ian field" wrote in message
...
Its probably too much to hope that I can find any actual data, or for that
matter there's any standard for colour coding.

Does anyone have any generic info on typical properties of this type of
core?

TIA.

On Mon, 28 Dec 2009 20:58:35 -0600, "Tim Williams"
wrote:

You mean the ugly yellow and white ones? Powdered iron, I think mix 23 or
27 or somesuch. Amazingly, I think most manufacturers actually follow this
coloring.

Lossy as hell, so put on a lot of turns, keep AC voltage low, and ripple
current even lower. Otherwise, use a fan.

Typical sizes are around 130 nH/T^2, and saturation at maybe 500 At.

Tim

These guys make them for example.

http://www.micrometals.com/

I have used theirs and a compatible range from Asia.

"Tim Williams" wrote in message
...
You mean the ugly yellow and white ones? Powdered iron, I think mix 23 or
27 or somesuch. Amazingly, I think most manufacturers actually follow
this coloring.

Some are yellow, but more often pale blue or duck egg green (as seen on
underside of WW2 fighter planes), I think I may even have seen the
occasional red one.


Lossy as hell, so put on a lot of turns, keep AC voltage low, and ripple
current even lower. Otherwise, use a fan.

All the one's I've found on motherboards have very few turns of pretty thick
wire.


Typical sizes are around 130 nH/T^2, and saturation at maybe 500 At.

Tim

On Tue, 29 Dec 2009 16:34:00 -0000, "ian field"
wrote:


"Tim Williams" wrote in message
...
You mean the ugly yellow and white ones? Powdered iron, I think mix 23 or
27 or somesuch. Amazingly, I think most manufacturers actually follow
this coloring.

Some are yellow, but more often pale blue or duck egg green (as seen on
underside of WW2 fighter planes), I think I may even have seen the
occasional red one.


Lossy as hell, so put on a lot of turns, keep AC voltage low, and ripple
current even lower. Otherwise, use a fan.

All the one's I've found on motherboards have very few turns of pretty thick
wire.


Typical sizes are around 130 nH/T^2, and saturation at maybe 500 At.

Tim


Still sounds like the Micrometals style of marking iron dust cores
where the colours indicate the material. Normally 1 colour on 3 sides
and the second colour on the 4th side.

Yellow/white is a -26
Green/blue is a -52

"Raveninghorde" raveninghorde@invalid wrote in message
...
On Tue, 29 Dec 2009 16:34:00 -0000, "ian field"
wrote:


"Tim Williams" wrote in message
...
You mean the ugly yellow and white ones? Powdered iron, I think mix 23
or
27 or somesuch. Amazingly, I think most manufacturers actually follow
this coloring.

Some are yellow, but more often pale blue or duck egg green (as seen on
underside of WW2 fighter planes), I think I may even have seen the
occasional red one.


Lossy as hell, so put on a lot of turns, keep AC voltage low, and ripple
current even lower. Otherwise, use a fan.

All the one's I've found on motherboards have very few turns of pretty
thick
wire.


Typical sizes are around 130 nH/T^2, and saturation at maybe 500 At.

Tim


Still sounds like the Micrometals style of marking iron dust cores
where the colours indicate the material. Normally 1 colour on 3 sides
and the second colour on the 4th side.

Yellow/white is a -26
Green/blue is a -52

Can't recall having seen any 2-tone cores as yet.

"ian field" wrote in message
...

"Raveninghorde" raveninghorde@invalid wrote in message
...
On Tue, 29 Dec 2009 16:34:00 -0000, "ian field"
wrote:


"Tim Williams" wrote in message
...
You mean the ugly yellow and white ones? Powdered iron, I think mix 23
or
27 or somesuch. Amazingly, I think most manufacturers actually follow
this coloring.

Some are yellow, but more often pale blue or duck egg green (as seen on
underside of WW2 fighter planes), I think I may even have seen the
occasional red one.


Lossy as hell, so put on a lot of turns, keep AC voltage low, and
ripple
current even lower. Otherwise, use a fan.

All the one's I've found on motherboards have very few turns of pretty
thick
wire.


Typical sizes are around 130 nH/T^2, and saturation at maybe 500 At.

Tim


Still sounds like the Micrometals style of marking iron dust cores
where the colours indicate the material. Normally 1 colour on 3 sides
and the second colour on the 4th side.

Yellow/white is a -26
Green/blue is a -52

Can't recall having seen any 2-tone cores as yet.

You'll find the Yellow / white ones inside computer power supplies, they're
fairly popular.

"ian field" wrote in message
...
Some are yellow, but more often pale blue or duck egg green (as seen on
underside of WW2 fighter planes), I think I may even have seen the
occasional red one.

Those may be MPP or other variations. Not quite as lossy, though still
resistive compared to ferrite (big deal, ferrite is practically an
insulator).

Lossy as hell, so put on a lot of turns, keep AC voltage low, and ripple
current even lower. Otherwise, use a fan.

All the one's I've found on motherboards have very few turns of pretty
thick wire.

Yeah. They also run at fairly low voltage (5V input, 1.2ish output?),
probably low ripple (high frequency), and with some air flow (inside a
computer, fans abound). Still, that's easily 2V/turn they're applying.

I never did quite understand powdered iron cores of any type. Try building
a blocking oscillator with one, it'll cook in no time. Must be the ripple
(a BO running continuous is essentially a BCM boost converter, so ripple is
maximal). Every time I think of putting in an inductor with high ripple, I
think, how the **** is this going to not melt, ah hell, I'll get out the
gapped ferrite and be done with it...

I've also seen glossy gray (epoxy coated) cores, often in common mode
chokes. This I believe is high-mu MPP, so it has fair CM inductance, but
because mu isn't as high as ferrite (~500, as opposed to 5k), it also has
some differential (leakage) inductance, which helps filter noise.

Tim

--
Deep Friar: a very philosophical monk.
Website: http://webpages.charter.net/dawill/tmoranwms

"Tim Williams" wrote in message
...
"ian field" wrote in message
...
Some are yellow, but more often pale blue or duck egg green (as seen on
underside of WW2 fighter planes), I think I may even have seen the
occasional red one.

Those may be MPP or other variations. Not quite as lossy, though still
resistive compared to ferrite (big deal, ferrite is practically an
insulator).

Lossy as hell, so put on a lot of turns, keep AC voltage low, and ripple
current even lower. Otherwise, use a fan.

All the one's I've found on motherboards have very few turns of pretty
thick wire.

Yeah. They also run at fairly low voltage (5V input, 1.2ish output?),
probably low ripple (high frequency),

What sort of frequency limit can I expect with these sort of cores?