Guest
On Sun, 18 Aug 2019 07:30:36 GMT, Jan Panteltje
<pNaOnStPeAlMtje@yahoo.com> wrote:
I guess the two small ferrite U pieces form a toroidal loop, which
would give pretty good coupling between the coils. I would prefer less
coupling in a line filter, to block both differential and common-mode
spikes.
Not much ferrite there, and lots of wire. Probably saturates easily
with DC load current.
Regarding saturation and stored energy, when I was thermal testing the
Schaffner I connected it to a bench supply, 2 volts and current
limiting at 3 amps. When I disconnected, I got a nice little spark,
from stored energy in the inductor.
I've never calibrated sparks. How many nanojoules does it take to make
a visible spark? I used to make CD ignitions for motorcycles, and I
recall that 50 mJ was a fat, noisy spark.
<pNaOnStPeAlMtje@yahoo.com> wrote:
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.
I guess the two small ferrite U pieces form a toroidal loop, which
would give pretty good coupling between the coils. I would prefer less
coupling in a line filter, to block both differential and common-mode
spikes.
Not much ferrite there, and lots of wire. Probably saturates easily
with DC load current.
Regarding saturation and stored energy, when I was thermal testing the
Schaffner I connected it to a bench supply, 2 volts and current
limiting at 3 amps. When I disconnected, I got a nice little spark,
from stored energy in the inductor.
I've never calibrated sparks. How many nanojoules does it take to make
a visible spark? I used to make CD ignitions for motorcycles, and I
recall that 50 mJ was a fat, noisy spark.