"John S" <Sophi.2@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. Tim -- Deep Friar: a very philosophical monk. Website: http://webpages.charter.net/dawill/tmoranwms
Baxandall class-D oscillator squegging and the VBIC model
Started by ●January 13, 2012
Reply by ●January 14, 20122012-01-14
Reply by ●January 14, 20122012-01-14
On Jan 14, 10:25=A0pm, John Larkin <jjlar...@highNOTlandTHIStechnologyPART.com> wrote:> On Sat, 14 Jan 2012 10:59:47 -0800 (PST),BillSloman > > > > > > > > > > <bill.slo...@ieee.org> wrote: > >On Jan 14, 7:16=A0pm, John Larkin > ><jjlar...@highNOTlandTHIStechnologyPART.com> wrote: > >> On Sat, 14 Jan 2012 03:00:55 -0800 (PST),BillSloman > > >> <bill.slo...@ieee.org> wrote: > >> >On Jan 14, 11:09=A0am, John Devereux <j...@devereux.me.uk> wrote: > >> >> BillSloman<bill.slo...@ieee.org> writes: > >> >> > On Jan 14, 5:36=A0am, 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 b=ipolar> >> >> >> >switches. An LTSpice circuit using the Gummel-Poon model for th=e> >> >> >> >bipolar transistors doesn't show this - it settles down to a st=able> >> >> >> >sinusoidal oscillation within less than a hundred cycles. > > >> >> >> >The obvious effect of using a high value inductor is that the c=urrent> >> >> >> >through the inductor over-shoots dramatically at start-up and a=ctually> >> >> >> >reverses polarity as it recovers, so the bipolar transistors br=iefly> >> >> >> >run inverted (emitter and collector diffusions swap roles). In =real> >> >> >> >life this clearly makes the circuit =A0behave very oddly, but t=he Gummel-> >> >> >> >Poon model equally clearly doesn't capture this particular oddn=ess.> > >> >> >> >VBIC might do better, but it doesn't with the model parameters =that> >> >> >> >I =A0bodged out of Gummel-Poon parameters. Somebody who had a b=etter -> >> >> >> >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. > > >> >> Well there's one way to find out isn't there? :) > > >> >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 wast=e> >> >of time. > > >> If the behavior of this oscillator is a waste of time, give it up. > > >> If it were interesting to me, I'd have one running in about 30 > >> minutes, on a handsome, dremeled, labeled slice of copperclad. > > >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. > > You can wind a pot core in a few minutes, by hand.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
Reply by ●January 14, 20122012-01-14
On Sat, 14 Jan 2012 14:50:38 -0800 (PST), Bill Sloman <bill.sloman@ieee.org> wrote:>On Jan 14, 10:25�pm, John Larkin ><jjlar...@highNOTlandTHIStechnologyPART.com> wrote: >> On Sat, 14 Jan 2012 10:59:47 -0800 (PST),BillSloman >> >> >> >> >> >> >> >> >> >> <bill.slo...@ieee.org> wrote: >> >On Jan 14, 7:16�pm, John Larkin >> ><jjlar...@highNOTlandTHIStechnologyPART.com> wrote: >> >> On Sat, 14 Jan 2012 03:00:55 -0800 (PST),BillSloman >> >> >> <bill.slo...@ieee.org> wrote: >> >> >On Jan 14, 11:09�am, John Devereux <j...@devereux.me.uk> wrote: >> >> >> BillSloman<bill.slo...@ieee.org> writes: >> >> >> > 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. >> >> >> >> Well there's one way to find out isn't there? :) >> >> >> >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. >> >> >> If the behavior of this oscillator is a waste of time, give it up. >> >> >> If it were interesting to me, I'd have one running in about 30 >> >> minutes, on a handsome, dremeled, labeled slice of copperclad. >> >> >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. >> >> You can wind a pot core in a few minutes, by hand. > >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.Things like this: 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
Reply by ●January 14, 20122012-01-14
On Jan 14, 11:34=A0pm, "Tim Williams" <tmoran...@charter.net> wrote:> "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. =A0This still affects the high frequency impedance, increasin=g> distortion, but not by as much. =A0Or an RLC, so it resonantly damps agai=nst> 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 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%20o= scillator2.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
Reply by ●January 14, 20122012-01-14
On Jan 15, 12:05=A0am, John Larkin <jjlar...@highNOTlandTHIStechnologyPART.com> wrote:> On Sat, 14 Jan 2012 14:50:38 -0800 (PST),BillSloman > > > > > > > > > > <bill.slo...@ieee.org> wrote: > >On Jan 14, 10:25=A0pm, John Larkin > ><jjlar...@highNOTlandTHIStechnologyPART.com> wrote: > >> On Sat, 14 Jan 2012 10:59:47 -0800 (PST),BillSloman > > >> <bill.slo...@ieee.org> wrote: > >> >On Jan 14, 7:16=A0pm, John Larkin > >> ><jjlar...@highNOTlandTHIStechnologyPART.com> wrote: > >> >> On Sat, 14 Jan 2012 03:00:55 -0800 (PST),BillSloman > > >> >> <bill.slo...@ieee.org> wrote: > >> >> >On Jan 14, 11:09=A0am, John Devereux <j...@devereux.me.uk> wrote: > >> >> >> BillSloman<bill.slo...@ieee.org> writes: > >> >> >> > On Jan 14, 5:36=A0am, 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 l=ife if you> >> >> >> >> >build it with a high value inductance in the current feed an=d 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 th=e current> >> >> >> >> >through the inductor over-shoots dramatically at start-up an=d 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 =A0behave very oddly, bu=t the Gummel-> >> >> >> >> >Poon model equally clearly doesn't capture this particular o=ddness.> > >> >> >> >> >VBIC might do better, but it doesn't with the model paramete=rs that> >> >> >> >> >I =A0bodged out of Gummel-Poon parameters. Somebody who had =a better -> >> >> >> >> >some - understanding of the VBIC parameters might well be ab=le to do> >> >> >> >> >better. > > >> >> >> >> It seems to wobble a bit on startup, but doesn't actually squ=eg even> >> >> >> >> with a full henry as the feed inductor. > > >> >> >> > That's what I'm complaining about. A real circuit would almost > >> >> >> > certainly squeg. > > >> >> >> Well there's one way to find out isn't there? :) > > >> >> >The last one I built with an over-sized oscillator (which was the > >> >> >first one I ever built, more than forty years ago) certainly squeg=ged.> >> >> >Building another just to prove the point would be something of a w=aste> >> >> >of time. > > >> >> If the behavior of this oscillator is a waste of time, give it up. > > >> >> If it were interesting to me, I'd have one running in about 30 > >> >> minutes, on a handsome, dremeled, labeled slice of copperclad. > > >> >A bit extravagant for a 16kHz oscillator. If I get enthusiastic enoug=h> >> >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. > > >> You can wind a pot core in a few minutes, by hand. > > >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. > > Things like this: > > http://search.digikey.com/us/en/products/DRQ74-220-R/513-1148-6-ND/19... > > 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 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.> 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.pdfT1 and T2? -- Bill Sloman, Nijmegen
Reply by ●January 14, 20122012-01-14
On Sat, 14 Jan 2012 18:03:56 -0800 (PST), Bill Sloman <bill.sloman@ieee.org> wrote:>On Jan 15, 12:05�am, John Larkin ><jjlar...@highNOTlandTHIStechnologyPART.com> wrote: >> On Sat, 14 Jan 2012 14:50:38 -0800 (PST),BillSloman >> >> >> >> >> >> >> >> >> >> <bill.slo...@ieee.org> wrote: >> >On Jan 14, 10:25�pm, John Larkin >> ><jjlar...@highNOTlandTHIStechnologyPART.com> wrote: >> >> On Sat, 14 Jan 2012 10:59:47 -0800 (PST),BillSloman >> >> >> <bill.slo...@ieee.org> wrote: >> >> >On Jan 14, 7:16�pm, John Larkin >> >> ><jjlar...@highNOTlandTHIStechnologyPART.com> wrote: >> >> >> On Sat, 14 Jan 2012 03:00:55 -0800 (PST),BillSloman >> >> >> >> <bill.slo...@ieee.org> wrote: >> >> >> >On Jan 14, 11:09�am, John Devereux <j...@devereux.me.uk> wrote: >> >> >> >> BillSloman<bill.slo...@ieee.org> writes: >> >> >> >> > 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. >> >> >> >> >> Well there's one way to find out isn't there? :) >> >> >> >> >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. >> >> >> >> If the behavior of this oscillator is a waste of time, give it up. >> >> >> >> If it were interesting to me, I'd have one running in about 30 >> >> >> minutes, on a handsome, dremeled, labeled slice of copperclad. >> >> >> >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. >> >> >> You can wind a pot core in a few minutes, by hand. >> >> >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. >> >> Things like this: >> >> http://search.digikey.com/us/en/products/DRQ74-220-R/513-1148-6-ND/19... >> >> 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 >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?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
Reply by ●January 15, 20122012-01-15
"John Larkin" <jjlarkin@highNOTlandTHIStechnologyPART.com> wrote in message news:o3h4h71brpmpbm3p8olm68k40930es5qs2@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. 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 -- Deep Friar: a very philosophical monk. Website: http://webpages.charter.net/dawill/tmoranwms
Reply by ●January 15, 20122012-01-15
On Jan 15, 4:21=A0am, John Larkin <jjlar...@highNOTlandTHIStechnologyPART.com> wrote:> On Sat, 14 Jan 2012 18:03:56 -0800 (PST), Bill Sloman > > > > > > > > > > <bill.slo...@ieee.org> wrote: > >On Jan 15, 12:05=A0am, John Larkin > ><jjlar...@highNOTlandTHIStechnologyPART.com> wrote: > >> On Sat, 14 Jan 2012 14:50:38 -0800 (PST),BillSloman > > >> <bill.slo...@ieee.org> wrote: > >> >On Jan 14, 10:25=A0pm, John Larkin > >> ><jjlar...@highNOTlandTHIStechnologyPART.com> wrote: > >> >> On Sat, 14 Jan 2012 10:59:47 -0800 (PST),BillSloman > > >> >> <bill.slo...@ieee.org> wrote: > >> >> >On Jan 14, 7:16=A0pm, John Larkin > >> >> ><jjlar...@highNOTlandTHIStechnologyPART.com> wrote: > >> >> >> On Sat, 14 Jan 2012 03:00:55 -0800 (PST),BillSloman > > >> >> >> <bill.slo...@ieee.org> wrote: > >> >> >> >On Jan 14, 11:09=A0am, John Devereux <j...@devereux.me.uk> wrot=e:> >> >> >> >> BillSloman<bill.slo...@ieee.org> writes: > >> >> >> >> > On Jan 14, 5:36=A0am, 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 rea=l 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 t=o 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 transist=ors briefly> >> >> >> >> >> >run inverted (emitter and collector diffusions swap roles=). In real> >> >> >> >> >> >life this clearly makes the circuit =A0behave very oddly,=but the Gummel-> >> >> >> >> >> >Poon model equally clearly doesn't capture this particula=r oddness.> > >> >> >> >> >> >VBIC might do better, but it doesn't with the model param=eters that> >> >> >> >> >> >I =A0bodged out of Gummel-Poon parameters. Somebody who h=ad 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 alm=ost> >> >> >> >> > certainly squeg. > > >> >> >> >> Well there's one way to find out isn't there? :) > > >> >> >> >The last one I built with an over-sized oscillator (which was t=he> >> >> >> >first one I ever built, more than forty years ago) certainly sq=uegged.> >> >> >> >Building another just to prove the point would be something of =a waste> >> >> >> >of time. > > >> >> >> If the behavior of this oscillator is a waste of time, give it u=p.> > >> >> >> If it were interesting to me, I'd have one running in about 30 > >> >> >> minutes, on a handsome, dremeled, labeled slice of copperclad. > > >> >> >A bit extravagant for a 16kHz oscillator. If I get enthusiastic en=ough> >> >> >to build one I'll put it on a perforated prototyping board. I rath=er> >> >> >like the one Farnell sells that comes with a "collander ground pla=ne"> >> >> >on the component side of the board. The copper rings around the ho=les> >> >> >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. > > >> >> You can wind a pot core in a few minutes, by hand. > > >> >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. > > >> Things like this: > > >>http://search.digikey.com/us/en/products/DRQ74-220-R/513-1148-6-ND/19..=.> > >> 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 > >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. > > >> 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? > > 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.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
Reply by ●January 15, 20122012-01-15
On Sun, 15 Jan 2012 02:25:49 -0800 (PST), Bill Sloman <bill.sloman@ieee.org> wrote:>On Jan 15, 4:21�am, John Larkin ><jjlar...@highNOTlandTHIStechnologyPART.com> wrote: >> On Sat, 14 Jan 2012 18:03:56 -0800 (PST), Bill Sloman >> >> >> >> >> >> >> >> >> >> <bill.slo...@ieee.org> wrote: >> >On Jan 15, 12:05�am, John Larkin >> ><jjlar...@highNOTlandTHIStechnologyPART.com> wrote: >> >> On Sat, 14 Jan 2012 14:50:38 -0800 (PST),BillSloman >> >> >> <bill.slo...@ieee.org> wrote: >> >> >On Jan 14, 10:25�pm, John Larkin >> >> ><jjlar...@highNOTlandTHIStechnologyPART.com> wrote: >> >> >> On Sat, 14 Jan 2012 10:59:47 -0800 (PST),BillSloman >> >> >> >> <bill.slo...@ieee.org> wrote: >> >> >> >On Jan 14, 7:16�pm, John Larkin >> >> >> ><jjlar...@highNOTlandTHIStechnologyPART.com> wrote: >> >> >> >> On Sat, 14 Jan 2012 03:00:55 -0800 (PST),BillSloman >> >> >> >> >> <bill.slo...@ieee.org> wrote: >> >> >> >> >On Jan 14, 11:09�am, John Devereux <j...@devereux.me.uk> wrote: >> >> >> >> >> BillSloman<bill.slo...@ieee.org> writes: >> >> >> >> >> > 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. >> >> >> >> >> >> Well there's one way to find out isn't there? :) >> >> >> >> >> >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. >> >> >> >> >> If the behavior of this oscillator is a waste of time, give it up. >> >> >> >> >> If it were interesting to me, I'd have one running in about 30 >> >> >> >> minutes, on a handsome, dremeled, labeled slice of copperclad. >> >> >> >> >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. >> >> >> >> You can wind a pot core in a few minutes, by hand. >> >> >> >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. >> >> >> Things like this: >> >> >>http://search.digikey.com/us/en/products/DRQ74-220-R/513-1148-6-ND/19... >> >> >> 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 >> >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? >> >> 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. > >Unless you want other people to know what you are talking about.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.> >> 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.If you allow yourself to think, more opportunities are available. Add "gain control device" to the list. Maybe even "delay line." John
Reply by ●January 15, 20122012-01-15
On Jan 15, 6:06=A0pm, John Larkin <jjlar...@highNOTlandTHIStechnologyPART.com> wrote:> On Sun, 15 Jan 2012 02:25:49 -0800 (PST), Bill Sloman > > > > > > > > > > <bill.slo...@ieee.org> wrote: > >On Jan 15, 4:21=A0am, John Larkin > ><jjlar...@highNOTlandTHIStechnologyPART.com> wrote: > >> On Sat, 14 Jan 2012 18:03:56 -0800 (PST), Bill Sloman > > >> <bill.slo...@ieee.org> wrote: > >> >On Jan 15, 12:05=A0am, John Larkin > >> ><jjlar...@highNOTlandTHIStechnologyPART.com> wrote: > >> >> On Sat, 14 Jan 2012 14:50:38 -0800 (PST),BillSloman > > >> >> <bill.slo...@ieee.org> wrote: > >> >> >On Jan 14, 10:25=A0pm, John Larkin > >> >> ><jjlar...@highNOTlandTHIStechnologyPART.com> wrote: > >> >> >> On Sat, 14 Jan 2012 10:59:47 -0800 (PST),BillSloman > > >> >> >> <bill.slo...@ieee.org> wrote: > >> >> >> >On Jan 14, 7:16=A0pm, John Larkin > >> >> >> ><jjlar...@highNOTlandTHIStechnologyPART.com> wrote: > >> >> >> >> On Sat, 14 Jan 2012 03:00:55 -0800 (PST),BillSloman > > >> >> >> >> <bill.slo...@ieee.org> wrote: > >> >> >> >> >On Jan 14, 11:09=A0am, John Devereux <j...@devereux.me.uk> w=rote:> >> >> >> >> >> BillSloman<bill.slo...@ieee.org> writes: > >> >> >> >> >> > On Jan 14, 5:36=A0am, 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 f=eed and bipolar> >> >> >> >> >> >> >switches. An LTSpice circuit using the Gummel-Poon mod=el for the> >> >> >> >> >> >> >bipolar transistors doesn't show this - it settles dow=n to a stable> >> >> >> >> >> >> >sinusoidal oscillation within less than a hundred cycl=es.> > >> >> >> >> >> >> >The obvious effect of using a high value inductor is t=hat the current> >> >> >> >> >> >> >through the inductor over-shoots dramatically at start=-up and actually> >> >> >> >> >> >> >reverses polarity as it recovers, so the bipolar trans=istors briefly> >> >> >> >> >> >> >run inverted (emitter and collector diffusions swap ro=les). In real> >> >> >> >> >> >> >life this clearly makes the circuit =A0behave very odd=ly, but the Gummel-> >> >> >> >> >> >> >Poon model equally clearly doesn't capture this partic=ular oddness.> > >> >> >> >> >> >> >VBIC might do better, but it doesn't with the model pa=rameters that> >> >> >> >> >> >> >I =A0bodged out of Gummel-Poon parameters. Somebody wh=o 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 actual=ly squeg even> >> >> >> >> >> >> with a full henry as the feed inductor. > > >> >> >> >> >> > That's what I'm complaining about. A real circuit would =almost> >> >> >> >> >> > certainly squeg. > > >> >> >> >> >> Well there's one way to find out isn't there? :) > > >> >> >> >> >The last one I built with an over-sized oscillator (which wa=s 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. > > >> >> >> >> If the behavior of this oscillator is a waste of time, give i=t up.> > >> >> >> >> If it were interesting to me, I'd have one running in about 3=0> >> >> >> >> minutes, on a handsome, dremeled, labeled slice of copperclad=.> > >> >> >> >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 r=ather> >> >> >> >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 pa=rts if> >> >> >> >you want to mix and match. > > >> >> >> >It will take a bit longer than half an hour - winding transform=ers is> >> >> >> >tedious, even when you've got access to a coil winding machine. > > >> >> >> You can wind a pot core in a few minutes, by hand. > > >> >> >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 famili=ar> >> >> >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. > > >> >> Things like this: > > >> >>http://search.digikey.com/us/en/products/DRQ74-220-R/513-1148-6-ND/1=9...> > >> >> People call these dual-winding inductors, probably because they are > >> >> characterized to carry a lot of DC current. Of course they work nic=ely> >> >> as transformers. > > >> >It'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. > > >> >> 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? > > >> 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. > > >Unless you want other people to know what you are talking about. > > 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. > > > > >> 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. > > If you allow yourself to think, more opportunities are available. Add > "gain control device" to the list. Maybe even "delay line."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
