This will reduce the impedance at the operating frequency, which is just as bad.
Now, you could add an R+L, so it's lossy only at the low frequencies it squeggs at. This still affects the high frequency impedance, increasing distortion, but not by as much. Or an RLC, so it resonantly damps against the circuit (which itself looks like a capacitor), which requires tight tuning, but can achieve even higher out-of-band impedance.
Tim
if you
ipolar
eable
urrent
ctually
iefly
real
he Gummel-
ess.
that
etter -
to do
even
. eI know. I've done it. It doesn't have to take long to be tedious.
Any particular "dual-winding" inductor? It's not a name I'm familiar with. As far as I'm concerned, any inductor carrying two or more separate but magnetically linked windings is either a transformer or a common mode choke.
-- Bill Sloman, Nijmegen
you
bipolar
current
actually
Gummel-
Things like this:
People call these dual-winding inductors, probably because they are characterized to carry a lot of DC current. Of course they work nicely as transformers.
I used their big brothers in a power supply that we discussed here a while back.
ftp://jjlarkin.lmi.net/ESM_power.pdf
John
g
nst
Fairly early on it was appreciated that complicating the feed inductor by adding an extra LC section to block the second harmonic component reduced the harmonic content of the sinusoidal output without much damage the efficiency. It's mentioned on my web-site
According to Tony Williams it was demonstrated in the early 1960s, but tuning the resonant trap to match actual oscillator frequency was too expensive to make it a practical option.
-- Bill Sloman, Nijmegen
ife if you
d bipolar
the
stable
e current
d actually
briefly
In real
t the Gummel-
ddness.
rs that
a better -
le to do
eg even
ged.
aste
hIt's the first time I've heard of it being called a dual-winding inductor. There one in my Peltier thermostat paper
Sloman A.W., Buggs P., Molloy J., and Stewart D. =93A microcontroller- based driver to stabilise the temperature of an optical stage to 1mK in the range 4C to 38C, using a Peltier heat pump and a thermistor sensor=94 Measurement Science and Technology, 7 1653-64 (1996)
I called it a balun on page 1663 and in Figure 8. The - English - supplier called it a common mode choke.
Lots of people do.
T1 and T2?
-- Bill Sloman, Nijmegen
if you
bipolar
stable
current
actually
briefly
real
Gummel-
oddness.
that
better -
to do
even
I used them as transformers so I called them transformers. PADS lets you do that.
The other reason they are called "inductors" is that they have a specified inductance and tolerance. Transformers are seldom specified for inductance, and seldom specified for their DC current capacity.
It really doesn't matter what you call them. What you call them shouldn't constrain what you are willing to use them for. You could use these as baluns, common-mode chokes, inductors, power transformers, signal transformers, flyback transformers, resistors, or RTDs. Nice little parts.
John
"John Larkin" wrote in message news: snipped-for-privacy@4ax.com...
I hi-potted a $1.60 common mode choke at 15kV (peak, AC) between windings. Leakage is big of course, but still usable for a few things.
Planar transformers of course you can use however the hell you want; just make sure you have enough clearance around the routed holes to stand off the voltage you need. Slower to design in, but as cheap, and lower leakage.
Tim
e:
l life if you
and bipolar
for the
o a stable
the current
and actually
ors briefly
). In real
but the Gummel-
r oddness.
eters that
ad a better -
able to do
squeg even
ost
he
uegged.
a waste
p.
ough
er
ne"
les
if
is
a .Unless you want other people to know what you are talking about.
Obviously.
They are a bit bulky for use as resistors and RTDs. The bulk might be useful if you wanted to dissipate a significant amount of power, but it strikes me as an expensive way of getting it.
-- Bill Sloman, Nijmegen
life if you
bipolar
the
stable
current
actually
briefly
In real
the Gummel-
oddness.
parameters that
better -
able to do
squeg even
squegged.
waste
We follow proper conventions for reference designators. A resistor is R1, not RN1 or RV1 or POT1. A transistor is Q, not T or TR or TRN or any of that nonsense. Since thess parts look like a transformer [1] on the schematic and act like a transformer, I called them T on the schematic. When we use these as inductors, we put the windings in series or in parallel and call them L.
[1] except that they have two cores. That's because the part was created as two inductors, and we plopped them alongside one another to make it look like a transformer.If you allow yourself to think, more opportunities are available. Add "gain control device" to the list. Maybe even "delay line."
John
rote:
real life if you
eed and bipolar
el for the
n to a stable
es.
hat the current
-up and actually
istors briefly
les). In real
ly, but the Gummel-
ular oddness.
rameters that
o had a better -
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ly squeg even
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s the
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t up.
0 .enough
ather
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rts if
ers is
ar
or a
9...ely
- aWith two coils you could use one as a "saturable reactor"
I've never seen it done. and would have thought - as the wikipedia article does - that the approach is close to obsolete.
You can build up delay lines out of all sorts of RLC components. I hadn't realised that common mode chokes had anything special to offer as the inductive components in such a synthesis.
does use two-coil inductors, but controls the coupling between the two coils - his example circuit (figure 7) relies on having 50% coupling, which a common mode choke wouldn't offer.
-- Bill Sloman, Nijmegen
life if you
and bipolar
for the
a stable
the current
and actually
transistors briefly
roles). In real
but the Gummel-
oddness.
parameters that
a better -
able to do
squeg even
almost
squegged.
waste
enough
plane"
holes
if
is
Probably not practical with this series of parts. They typically hit a thermal/current limit before magnetic saturation.
It never hurts to understand what parts can do.
Since it's probably bifalar wound, maybe its windings could be used as a twisted-pair transmission line, a delay line all on their own.
John
in real life if you
t feed and bipolar
model for the
down to a stable
ycles.
s that the current
art-up and actually
ansistors briefly
roles). In real
oddly, but the Gummel-
ticular oddness.
parameters that
who had a better -
ell be able to do
ually squeg even
ld almost
was the
nly squegged.
ng of a waste
e it up.
t 30
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I rather
nd plane"
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eer or a
D/19...
are
nicely
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Some are bifilar wound, some not. The length of the winding - and thus the delay - isn't something the manufacturer specifies all that tightly on the data sheet, and might change without notice if they changed core materials.
Probably not the ideal building block.
-- Bill Sloman, Nijmegen
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