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Baxandall class-D oscillator squegging and the VBIC model
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Bill Sloman
Jan 13, 2012, 8:44:04 PM1/13/12
to
The Baxandall parallel class-D oscillator "squegs" in real life if you
build it with a high value inductance in the current feed and bipolar
switches. An LTSpice circuit using the Gummel-Poon model for the
bipolar transistors doesn't show this - it settles down to a stable
sinusoidal oscillation within less than a hundred cycles.
The obvious effect of using a high value inductor is that the current
through the inductor over-shoots dramatically at start-up and actually
reverses polarity as it recovers, so the bipolar transistors briefly
run inverted (emitter and collector diffusions swap roles). In real
life this clearly makes the circuit behave very oddly, but the Gummel-
Poon model equally clearly doesn't capture this particular oddness.
VBIC might do better, but it doesn't with the model parameters that
I bodged out of Gummel-Poon parameters. Somebody who had a better -
some - understanding of the VBIC parameters might well be able to do
better.
Version 4
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TEXT -488 840 Left 2 !.model 2N3906A PNP(ibei=2.22716E-18 xii=3
Ea=1.11 Vef=16.8 \n+ Iben=7.558f Nen=1.536 Ikf=.293583 Xin=1.5
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Itf=4.881m rth=0. cth=0.\n+ Xtf=.7939 Vtf=10 Rbx=10)\n+ Level=9
--
Bill Sloman, Nijmegen
build it with a high value inductance in the current feed and bipolar
switches. An LTSpice circuit using the Gummel-Poon model for the
bipolar transistors doesn't show this - it settles down to a stable
sinusoidal oscillation within less than a hundred cycles.
The obvious effect of using a high value inductor is that the current
through the inductor over-shoots dramatically at start-up and actually
reverses polarity as it recovers, so the bipolar transistors briefly
run inverted (emitter and collector diffusions swap roles). In real
life this clearly makes the circuit behave very oddly, but the Gummel-
Poon model equally clearly doesn't capture this particular oddness.
VBIC might do better, but it doesn't with the model parameters that
I bodged out of Gummel-Poon parameters. Somebody who had a better -
some - understanding of the VBIC parameters might well be able to do
better.
Version 4
SHEET 1 3272 1144
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TEXT -488 840 Left 2 !.model 2N3906A PNP(ibei=2.22716E-18 xii=3
Ea=1.11 Vef=16.8 \n+ Iben=7.558f Nen=1.536 Ikf=.293583 Xin=1.5
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6993 pc=1.006 Fc=.5 \n+ Cje=10.39p Me=.6931 pe=.9937 Tr=10n Tf=181.2p
Itf=4.881m rth=0. cth=0.\n+ Xtf=.7939 Vtf=10 Rbx=10)\n+ Level=9
--
Bill Sloman, Nijmegen
Tim Wescott
Jan 13, 2012, 11:36:09 PM1/13/12
to
On Fri, 13 Jan 2012 17:44:04 -0800, Bill Sloman wrote:
> The Baxandall parallel class-D oscillator "squegs" in real life if you
> build it with a high value inductance in the current feed and bipolar
> switches. An LTSpice circuit using the Gummel-Poon model for the bipolar
> transistors doesn't show this - it settles down to a stable sinusoidal
> oscillation within less than a hundred cycles.
>
> The obvious effect of using a high value inductor is that the current
> through the inductor over-shoots dramatically at start-up and actually
> reverses polarity as it recovers, so the bipolar transistors briefly run
> inverted (emitter and collector diffusions swap roles). In real life
> this clearly makes the circuit behave very oddly, but the Gummel- Poon
> model equally clearly doesn't capture this particular oddness.
>
> VBIC might do better, but it doesn't with the model parameters that I
> bodged out of Gummel-Poon parameters. Somebody who had a better - some -
> understanding of the VBIC parameters might well be able to do better.
>
(LTSpice _schematic_ (Phil) snipped)
> The Baxandall parallel class-D oscillator "squegs" in real life if you
> build it with a high value inductance in the current feed and bipolar
> switches. An LTSpice circuit using the Gummel-Poon model for the bipolar
> transistors doesn't show this - it settles down to a stable sinusoidal
> oscillation within less than a hundred cycles.
>
> The obvious effect of using a high value inductor is that the current
> through the inductor over-shoots dramatically at start-up and actually
> reverses polarity as it recovers, so the bipolar transistors briefly run
> inverted (emitter and collector diffusions swap roles). In real life
> this clearly makes the circuit behave very oddly, but the Gummel- Poon
> model equally clearly doesn't capture this particular oddness.
>
> VBIC might do better, but it doesn't with the model parameters that I
> bodged out of Gummel-Poon parameters. Somebody who had a better - some -
> understanding of the VBIC parameters might well be able to do better.
>
Since it's balanced, why do you need a monster inductor there? Why not
use a resistor, or put a resistor in series with the L to dampen the
squegging?
--
My liberal friends think I'm a conservative kook.
My conservative friends think I'm a liberal kook.
Why am I not happy that they have found common ground?
Tim Wescott, Communications, Control, Circuits & Software
http://www.wescottdesign.com
John Larkin
Jan 13, 2012, 11:36:50 PM1/13/12
to
On Fri, 13 Jan 2012 17:44:04 -0800 (PST), Bill Sloman
<bill....@ieee.org> wrote:
>The Baxandall parallel class-D oscillator "squegs" in real life if you
>build it with a high value inductance in the current feed and bipolar
>switches. An LTSpice circuit using the Gummel-Poon model for the
>bipolar transistors doesn't show this - it settles down to a stable
>sinusoidal oscillation within less than a hundred cycles.
>
>The obvious effect of using a high value inductor is that the current
>through the inductor over-shoots dramatically at start-up and actually
>reverses polarity as it recovers, so the bipolar transistors briefly
>run inverted (emitter and collector diffusions swap roles). In real
>life this clearly makes the circuit behave very oddly, but the Gummel-
>Poon model equally clearly doesn't capture this particular oddness.
>
>VBIC might do better, but it doesn't with the model parameters that
>I bodged out of Gummel-Poon parameters. Somebody who had a better -
>some - understanding of the VBIC parameters might well be able to do
>better.
>
It seems to wobble a bit on startup, but doesn't actually squegg even
<bill....@ieee.org> wrote:
>The Baxandall parallel class-D oscillator "squegs" in real life if you
>build it with a high value inductance in the current feed and bipolar
>switches. An LTSpice circuit using the Gummel-Poon model for the
>bipolar transistors doesn't show this - it settles down to a stable
>sinusoidal oscillation within less than a hundred cycles.
>
>The obvious effect of using a high value inductor is that the current
>through the inductor over-shoots dramatically at start-up and actually
>reverses polarity as it recovers, so the bipolar transistors briefly
>run inverted (emitter and collector diffusions swap roles). In real
>life this clearly makes the circuit behave very oddly, but the Gummel-
>Poon model equally clearly doesn't capture this particular oddness.
>
>VBIC might do better, but it doesn't with the model parameters that
>I bodged out of Gummel-Poon parameters. Somebody who had a better -
>some - understanding of the VBIC parameters might well be able to do
>better.
>
with a full henry as the feed inductor.
Oscillators sure simulate slowly.
John
Bill Sloman
Jan 14, 2012, 4:56:34 AM1/14/12
to
On Jan 14, 5:36 am, John Larkin
> It seems to wobble a bit on startup, but doesn't actually squeg even
certainly squeg.
--
Bill Sloman, Nijmegen
> with a full henry as the feed inductor.
That's what I'm complaining about. A real circuit would almost
certainly squeg.
--
Bill Sloman, Nijmegen
Bill Sloman
Jan 14, 2012, 4:56:59 AM1/14/12
to
On Jan 14, 5:36 am, Tim Wescott <t...@seemywebsite.com> wrote:
> On Fri, 13 Jan 2012 17:44:04 -0800, Bill Sloman wrote:
> > The Baxandall parallel class-D oscillator "squegs" in real life if you
> > build it with a high value inductance in the current feed and bipolar
> > switches. An LTSpice circuit using the Gummel-Poon model for the bipolar
> > transistors doesn't show this - it settles down to a stable sinusoidal
> > oscillation within less than a hundred cycles.
>
> > The obvious effect of using a high value inductor is that the current
> > through the inductor over-shoots dramatically at start-up and actually
> > reverses polarity as it recovers, so the bipolar transistors briefly run
> > inverted (emitter and collector diffusions swap roles). In real life
> > this clearly makes the circuit behave very oddly, but the Gummel- Poon
> > model equally clearly doesn't capture this particular oddness.
>
> > VBIC might do better, but it doesn't with the model parameters that I
> > bodged out of Gummel-Poon parameters. Somebody who had a better - some -
> > understanding of the VBIC parameters might well be able to do better.
>
> (LTSpice _schematic_ (Phil) snipped)
>
> Since it's balanced, why do you need a monster inductor there? Why not
> use a resistor, or put a resistor in series with the L to dampen the
> squegging?
Using a big inductor reduces the level of odd harmonics (3rd, 5th etc)
> On Fri, 13 Jan 2012 17:44:04 -0800, Bill Sloman wrote:
> > The Baxandall parallel class-D oscillator "squegs" in real life if you
> > build it with a high value inductance in the current feed and bipolar
> > switches. An LTSpice circuit using the Gummel-Poon model for the bipolar
> > transistors doesn't show this - it settles down to a stable sinusoidal
> > oscillation within less than a hundred cycles.
>
> > The obvious effect of using a high value inductor is that the current
> > through the inductor over-shoots dramatically at start-up and actually
> > reverses polarity as it recovers, so the bipolar transistors briefly run
> > inverted (emitter and collector diffusions swap roles). In real life
> > this clearly makes the circuit behave very oddly, but the Gummel- Poon
> > model equally clearly doesn't capture this particular oddness.
>
> > VBIC might do better, but it doesn't with the model parameters that I
> > bodged out of Gummel-Poon parameters. Somebody who had a better - some -
> > understanding of the VBIC parameters might well be able to do better.
>
> (LTSpice _schematic_ (Phil) snipped)
>
> Since it's balanced, why do you need a monster inductor there? Why not
> use a resistor, or put a resistor in series with the L to dampen the
> squegging?
in the sine wave generated. Using an inductor at all is the kern of
the Class-D oscillator
http://home.planet.nl/~sloma000/0344_001_Baxandal.pdf
Adding more resistance in series with the inductor makes the circuit
less efficient. Jim William's versions get over 90% efficiency -
Linear Technology application notes AN45, AN49, AN51, AN55, AN61,
AN65.
If it were big enough, it might damp the overshoot on start-up enough
to prevent the initial reversal of current in the inductor, which
might - in turn - stop the squegging from starting.
--
Bill Sloman, Nijmegen
John Devereux
Jan 14, 2012, 5:09:55 AM1/14/12
to
--
John Devereux
Bill Sloman
Jan 14, 2012, 6:00:55 AM1/14/12
to
On Jan 14, 11:09 am, John Devereux <j...@devereux.me.uk> wrote:
The last one I built with an over-sized oscillator (which was the
first one I ever built, more than forty years ago) certainly squegged.
Building another just to prove the point would be something of a waste
of time. An example with a diode to prevent the current through the
inductor going the wrong way might make more sense.
--
Bill Sloman, Nijmegen
first one I ever built, more than forty years ago) certainly squegged.
Building another just to prove the point would be something of a waste
of time. An example with a diode to prevent the current through the
inductor going the wrong way might make more sense.
--
Bill Sloman, Nijmegen
John Devereux
Jan 14, 2012, 9:41:47 AM1/14/12
to
show up in the simulation, then the simulation is not going to be much
use for fixing it!
--
John Devereux
Bill Sloman
Jan 14, 2012, 10:40:14 AM1/14/12
to
- which is what the simulations seem to suggest - then one extra diode
might well fix it. If this were to work, I'd have found something -
thanks to the simulation - which Peter Baxandall (amongst many others,
including me and Tony Williams) had missed. If it were that simple,
someone should have found it out earlier, so it probably won't work.
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SYMATTR Type diode
Tim Wescott
Jan 14, 2012, 11:36:17 AM1/14/12
to
collectors, to force the transistors to only work one way.
--
Tim Wescott
Control system and signal processing consulting
www.wescottdesign.com
Tim Wescott
Jan 14, 2012, 11:38:51 AM1/14/12
to
On Sat, 14 Jan 2012 01:56:59 -0800, Bill Sloman wrote:
do you want? An astonishingly efficient oscillator that wastes some
power, but still works? Or an oscillator that is is astonishingly
efficient and useless?
John Larkin
Jan 14, 2012, 11:47:50 AM1/14/12
to
It's not a higher-order system. A cap in the base bias network could
push it over the edge, like a super-regen receiver.
But why don't you build one and see?
John
John Larkin
Jan 14, 2012, 1:16:54 PM1/14/12
to
If it were interesting to me, I'd have one running in about 30
minutes, on a handsome, dremeled, labeled slice of copperclad.
John
Bill Sloman
Jan 14, 2012, 1:59:47 PM1/14/12
to
On Jan 14, 7:16 pm, John Larkin
A bit extravagant for a 16kHz oscillator. If I get enthusiastic enough
to build one I'll put it on a perforated prototyping board. I rather
like the one Farnell sells that comes with a "collander ground plane"
on the component side of the board. The copper rings around the holes
on the track side can be chopped up to support surface mount parts if
you want to mix and match.
It will take a bit longer than half an hour - winding transformers is
tedious, even when you've got access to a coil winding machine.
--
Bill Sloman
to build one I'll put it on a perforated prototyping board. I rather
like the one Farnell sells that comes with a "collander ground plane"
on the component side of the board. The copper rings around the holes
on the track side can be chopped up to support surface mount parts if
you want to mix and match.
It will take a bit longer than half an hour - winding transformers is
tedious, even when you've got access to a coil winding machine.
--
Bill Sloman
Bill Sloman
Jan 14, 2012, 2:00:02 PM1/14/12
to
On Jan 14, 5:47 pm, John Larkin
feed inductor too big
http://home.planet.nl/~sloma000/0344_001_Baxandal.pdf
See Baxandall's footnote on page 752.
> But why don't you build one and see?
I've built several over the years. I've got no urgent need to build
one now.
--
Bill Sloman, Nijmegen
<jjlar...@highNOTlandTHIStechnologyPART.com> wrote:
> On Sat, 14 Jan 2012 01:56:34 -0800 (PST),BillSloman
>
> On Sat, 14 Jan 2012 01:56:34 -0800 (PST),BillSloman
>
> <bill.slo...@ieee.org> wrote:
> >On Jan 14, 5:36 am, John Larkin
> ><jjlar...@highNOTlandTHIStechnologyPART.com> wrote:
> >> On Fri, 13 Jan 2012 17:44:04 -0800 (PST),BillSloman
>
> >> <bill.slo...@ieee.org> wrote:
> >> >The Baxandall parallel class-D oscillator "squegs" in real life if you
> >> >build it with a high value inductance in the current feed and bipolar
> >> >switches. An LTSpice circuit using the Gummel-Poon model for the
> >> >bipolar transistors doesn't show this - it settles down to a stable
> >> >sinusoidal oscillation within less than a hundred cycles.
>
> >> >The obvious effect of using a high value inductor is that the current
> >> >through the inductor over-shoots dramatically at start-up and actually
> >> >reverses polarity as it recovers, so the bipolar transistors briefly
> >> >run inverted (emitter and collector diffusions swap roles). In real
> >> >life this clearly makes the circuit behave very oddly, but the Gummel-
> >> >Poon model equally clearly doesn't capture this particular oddness.
>
> >> >VBIC might do better, but it doesn't with the model parameters that
> >> >I bodged out of Gummel-Poon parameters. Somebody who had a better -
> >> >some - understanding of the VBIC parameters might well be able to do
> >> >better.
>
> >> It seems to wobble a bit on startup, but doesn't actually squeg even
> >> with a full henry as the feed inductor.
>
> >That's what I'm complaining about. A real circuit would almost
> >certainly squeg.
>
> I doubt it. The whole thing is dominated by the Q of the tuned circuit.
> >On Jan 14, 5:36 am, John Larkin
> ><jjlar...@highNOTlandTHIStechnologyPART.com> wrote:
> >> On Fri, 13 Jan 2012 17:44:04 -0800 (PST),BillSloman
>
> >> <bill.slo...@ieee.org> wrote:
> >> >The Baxandall parallel class-D oscillator "squegs" in real life if you
> >> >build it with a high value inductance in the current feed and bipolar
> >> >switches. An LTSpice circuit using the Gummel-Poon model for the
> >> >bipolar transistors doesn't show this - it settles down to a stable
> >> >sinusoidal oscillation within less than a hundred cycles.
>
> >> >The obvious effect of using a high value inductor is that the current
> >> >through the inductor over-shoots dramatically at start-up and actually
> >> >reverses polarity as it recovers, so the bipolar transistors briefly
> >> >run inverted (emitter and collector diffusions swap roles). In real
> >> >life this clearly makes the circuit behave very oddly, but the Gummel-
> >> >Poon model equally clearly doesn't capture this particular oddness.
>
> >> >VBIC might do better, but it doesn't with the model parameters that
> >> >I bodged out of Gummel-Poon parameters. Somebody who had a better -
> >> >some - understanding of the VBIC parameters might well be able to do
> >> >better.
>
> >> It seems to wobble a bit on startup, but doesn't actually squeg even
> >> with a full henry as the feed inductor.
>
> >That's what I'm complaining about. A real circuit would almost
> >certainly squeg.
>
> It's not a higher-order system. A cap in the base bias network could
> push it over the edge, like a super-regen receiver.
Doubt all you like. It squegs anyway, and always has, if you make the
> push it over the edge, like a super-regen receiver.
feed inductor too big
http://home.planet.nl/~sloma000/0344_001_Baxandal.pdf
See Baxandall's footnote on page 752.
> But why don't you build one and see?
one now.
--
Bill Sloman, Nijmegen
Bill Sloman
Jan 14, 2012, 2:15:40 PM1/14/12
to
make it perfectly clear that the circuit can be both efficient and
useful. A bigger feed inductor would just reduce the (odd) harmonic
content of the output. There's no perceptible even harmonic content.
It has been claimed here that using MOSFET switches rather than
bipolar transistors lets you use a big feed inductor and still avoid
squegging. My primary interest is trying to work out what causes the
squegging, rather than in coming up with a cure for the squegging when
it does happen.
If you can live with a slightly less efficient circuit, I think I've
got a variant that keeps the harmonics some 80dB below the
fundamental, which is better than you could do with any practical
inductor (short of a high temperature super-conductor coil in liquid
nitrogen).
--
Bill Sloman, Nijmegen
Bill Sloman
Jan 14, 2012, 2:03:30 PM1/14/12
to
series with each of the switching transistors - see today's version of
the circuit in my response to John Devereux. it doesn't help the
efficiency.
--
Bill Sloman,Nijmegen
John S
Jan 14, 2012, 3:39:08 PM1/14/12
to
a lower Q?
John Larkin
Jan 14, 2012, 4:25:44 PM1/14/12
to
ftp://jjlarkin.lmi.net/Z206_pcb.JPG
Or buy one of those dual-winding inductors for about a dollar.
Or not.
John
Bill Sloman
Jan 14, 2012, 5:32:03 PM1/14/12
to
On Jan 14, 9:39 pm, John S <Soph...@invalid.org> wrote:
> On 1/14/2012 3:56 AM,BillSlomanwrote:
It's no less inefficient. Any resistor carrying current is dissipating
heat.
--
Bill Sloman, Nijmegen
> On 1/14/2012 3:56 AM,BillSlomanwrote:
heat.
--
Bill Sloman, Nijmegen
Tim Williams
Jan 14, 2012, 5:34:02 PM1/14/12
to
"John S" <Sop...@invalid.org> wrote in message
news:jesp5i$man$1...@dont-email.me...
as bad.
Now, you could add an R+L, so it's lossy only at the low frequencies it
squeggs at. This still affects the high frequency impedance, increasing
distortion, but not by as much. Or an RLC, so it resonantly damps against
the circuit (which itself looks like a capacitor), which requires tight
tuning, but can achieve even higher out-of-band impedance.
Tim
--
Deep Friar: a very philosophical monk.
Website: http://webpages.charter.net/dawill/tmoranwms
news:jesp5i$man$1...@dont-email.me...
>> Adding more resistance in series with the inductor makes the circuit
>> less efficient.
>
> Can't the resistance be added in parallel with the inductor and achieve
> a lower Q?
This will reduce the impedance at the operating frequency, which is just
>> less efficient.
>
> Can't the resistance be added in parallel with the inductor and achieve
> a lower Q?
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
--
Deep Friar: a very philosophical monk.
Website: http://webpages.charter.net/dawill/tmoranwms
Bill Sloman
Jan 14, 2012, 5:50:38 PM1/14/12
to
On Jan 14, 10:25 pm, John Larkin
<jjlar...@highNOTlandTHIStechnologyPART.com> wrote:
> On Sat, 14 Jan 2012 10:59:47 -0800 (PST),BillSloman
I know. I've done it. It doesn't have to take long to be tedious.
> ftp://jjlarkin.lmi.net/Z206_pcb.JPG
>
> Or buy one of those dual-winding inductors for about a dollar.
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
<jjlar...@highNOTlandTHIStechnologyPART.com> wrote:
> On Sat, 14 Jan 2012 10:59:47 -0800 (PST),BillSloman
> ftp://jjlarkin.lmi.net/Z206_pcb.JPG
>
> Or buy one of those dual-winding inductors for about a dollar.
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
John Larkin
Jan 14, 2012, 6:05:49 PM1/14/12
to
http://search.digikey.com/us/en/products/DRQ74-220-R/513-1148-6-ND/1973246
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
Bill Sloman
Jan 14, 2012, 6:06:01 PM1/14/12
to
On Jan 14, 11:34 pm, "Tim Williams" <tmoran...@charter.net> wrote:
> "John S" <Soph...@invalid.org> wrote in message
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
http://home.planet.nl/~sloma000/Baxandall%20parallel-resonant%20Class-D%20oscillator2.htm
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
> "John S" <Soph...@invalid.org> wrote in message
>
> news:jesp5i$man$1...@dont-email.me...
>
> >> Adding more resistance in series with the inductor makes the circuit
> >> less efficient.
>
> > Can't the resistance be added in parallel with the inductor and achieve
> > a lower Q?
>
> This will reduce the impedance at the operating frequency, which is just
> as bad.
>
> Now, you could add an R+L, so it's lossy only at the low frequencies it
> squeggs at. This still affects the high frequency impedance, increasing
> distortion, but not by as much. Or an RLC, so it resonantly damps against
> the circuit (which itself looks like a capacitor), which requires tight
> tuning, but can achieve even higher out-of-band impedance.
Fairly early on it was appreciated that complicating the feed inductor
> news:jesp5i$man$1...@dont-email.me...
>
> >> Adding more resistance in series with the inductor makes the circuit
> >> less efficient.
>
> > Can't the resistance be added in parallel with the inductor and achieve
> > a lower Q?
>
> 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.
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
http://home.planet.nl/~sloma000/Baxandall%20parallel-resonant%20Class-D%20oscillator2.htm
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
Bill Sloman
Jan 14, 2012, 9:03:56 PM1/14/12
to
On Jan 15, 12:05 am, John Larkin
<jjlar...@highNOTlandTHIStechnologyPART.com> wrote:
> On Sat, 14 Jan 2012 14:50:38 -0800 (PST),BillSloman
> http://search.digikey.com/us/en/products/DRQ74-220-R/513-1148-6-ND/19...
inductor. There one in my Peltier thermostat paper
Sloman A.W., Buggs P., Molloy J., and Stewart D. “A 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” 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.
> I used their big brothers in a power supply that we discussed here a
> while back.
Lots of people do.
> ftp://jjlarkin.lmi.net/ESM_power.pdf
T1 and T2?
--
Bill Sloman, Nijmegen
<jjlar...@highNOTlandTHIStechnologyPART.com> wrote:
> On Sat, 14 Jan 2012 14:50:38 -0800 (PST),BillSloman
>
> 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.
It's the first time I've heard of it being called a dual-winding
> 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.
inductor. There one in my Peltier thermostat paper
Sloman A.W., Buggs P., Molloy J., and Stewart D. “A 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” 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.
> I used their big brothers in a power supply that we discussed here a
> while back.
> ftp://jjlarkin.lmi.net/ESM_power.pdf
T1 and T2?
--
Bill Sloman, Nijmegen
John Larkin
Jan 14, 2012, 10:21:44 PM1/14/12
to
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
Tim Williams
Jan 14, 2012, 11:56:29 PM1/14/12
to
"John Larkin" <jjla...@highNOTlandTHIStechnologyPART.com> wrote in
message news:o3h4h71brpmpbm3p8...@4ax.com...
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.
message news:o3h4h71brpmpbm3p8...@4ax.com...
> 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.
I hi-potted a $1.60 common mode choke at 15kV (peak, AC) between windings.
> 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.
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.
Bill Sloman
Jan 15, 2012, 5:25:49 AM1/15/12
to
On Jan 15, 4:21 am, John Larkin
Unless you want other people to know what you are talking about.
> What you call them
> shouldn't constrain what you are willing to use them for.
Obviously.
> You could
> use these as baluns, common-mode chokes, inductors, power
> transformers, signal transformers, flyback transformers, resistors, or
> RTDs. Nice little parts.
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
> 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.
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
John Larkin
Jan 15, 2012, 12:06:23 PM1/15/12
to
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.
>
>> What you call them
>> shouldn't constrain what you are willing to use them for.
>
>Obviously.
>
>> You could
>> use these as baluns, common-mode chokes, inductors, power
>> transformers, signal transformers, flyback transformers, resistors, or
>> RTDs. Nice little parts.
>
>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.
"gain control device" to the list. Maybe even "delay line."
John
Bill Sloman
Jan 15, 2012, 1:11:07 PM1/15/12
to
On Jan 15, 6:06 pm, John Larkin
With two coils you could use one as a "saturable reactor"
http://en.wikipedia.org/wiki/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.
http://jcatsc.com/media/TechnicalReports/02-CoupledInductorDelayFilter.pdf
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
<jjlar...@highNOTlandTHIStechnologyPART.com> wrote:
> On Sun, 15 Jan 2012 02:25:49 -0800 (PST), Bill Sloman
>
>
>
>
>
>
>
>
>
> On Sun, 15 Jan 2012 02:25:49 -0800 (PST), Bill Sloman
>
>
>
>
>
>
>
>
>
http://en.wikipedia.org/wiki/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.
http://jcatsc.com/media/TechnicalReports/02-CoupledInductorDelayFilter.pdf
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
John Larkin
Jan 15, 2012, 1:42:10 PM1/15/12
to
thermal/current limit before magnetic saturation.
>
>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.
>
>http://jcatsc.com/media/TechnicalReports/02-CoupledInductorDelayFilter.pdf
a twisted-pair transmission line, a delay line all on their own.
John
Bill Sloman
Jan 15, 2012, 2:40:28 PM1/15/12
to
On Jan 15, 7:42 pm, John Larkin
> >http://jcatsc.com/media/TechnicalReports/02-CoupledInductorDelayFilte...
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
<jjlar...@highNOTlandTHIStechnologyPART.com> wrote:
> On Sun, 15 Jan 2012 10:11:07 -0800 (PST), Bill Sloman
>
>
>
>
>
>
>
>
>
> On Sun, 15 Jan 2012 10:11:07 -0800 (PST), Bill Sloman
>
>
>
>
>
>
>
>
>
>
> 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.
Some are bifilar wound, some not. The length of the winding - and thus
> 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.
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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