John Larkin's LC oscillator
in [Design]
|
Prev: Skybuck's Universal Code Version 6 (The Fast Version)
Next: CCt to converter 24Vdc signals to 12Vdc signals
From: JosephKK on 16 Jun 2010 22:15 On Tue, 15 Jun 2010 20:45:37 -0700, John Larkin <jjlarkin(a)highNOTlandTHIStechnologyPART.com> wrote: >On Tue, 15 Jun 2010 20:36:11 -0700, >"JosephKK"<quiettechblue(a)yahoo.com> wrote: > >>On Mon, 14 Jun 2010 22:18:22 -0700, John Larkin >><jjlarkin(a)highNOTlandTHIStechnologyPART.com> wrote: >> >>>On Mon, 14 Jun 2010 22:06:53 -0700, >>>"JosephKK"<quiettechblue(a)yahoo.com> wrote: >>> >>>>On Mon, 14 Jun 2010 11:15:00 -0700, Jim Thompson >>>><To-Email-Use-The-Envelope-Icon(a)On-My-Web-Site.com> wrote: >>>> >>>>>On Mon, 14 Jun 2010 10:50:58 -0700 (PDT), dagmargoodboat(a)yahoo.com >>>>>wrote: >>>>> >><snip> >>>>>Class-A implies _linear_, does it not? Or do we have a Larkin >>>>>definition for today ?:-) >>>>> >>>> >>>>The definition i have always heard is that it is conducting through the >>>>whole cycle. Nothing about linearity. And that is one fougly non-linear >>>>circuit. >>> >>>Only if you want it to be. It can be designed to be a nice smooth >>>class A oscillator with precise automatic gain control that servoes >>>oscillation amplitude to almost exactly 2*Vcc, with a low TC. Not bad >>>for one transistor. >>> >>>John >> >>So post that version instead. > >I did, several days ago. > >ftp://jjlarkin.lmi.net/LC_YDx.gif No way sport, that is running deep class C. > >And I described it long before that. > >ftp://jjlarkin.lmi.net/Ships_Bell.JPG > >I can't help it if people keep over-driving it, and then complaining >that it's over-driven. > >John The output is reasonable like a proper TC oscillator, but it is running class C.
From: Jim Thompson on 16 Jun 2010 22:28 On Wed, 16 Jun 2010 19:15:30 -0700, "JosephKK"<quiettechblue(a)yahoo.com> wrote: >On Tue, 15 Jun 2010 20:45:37 -0700, John Larkin ><jjlarkin(a)highNOTlandTHIStechnologyPART.com> wrote: > >>On Tue, 15 Jun 2010 20:36:11 -0700, >>"JosephKK"<quiettechblue(a)yahoo.com> wrote: >> >>>On Mon, 14 Jun 2010 22:18:22 -0700, John Larkin >>><jjlarkin(a)highNOTlandTHIStechnologyPART.com> wrote: >>> >>>>On Mon, 14 Jun 2010 22:06:53 -0700, >>>>"JosephKK"<quiettechblue(a)yahoo.com> wrote: >>>> >>>>>On Mon, 14 Jun 2010 11:15:00 -0700, Jim Thompson >>>>><To-Email-Use-The-Envelope-Icon(a)On-My-Web-Site.com> wrote: >>>>> >>>>>>On Mon, 14 Jun 2010 10:50:58 -0700 (PDT), dagmargoodboat(a)yahoo.com >>>>>>wrote: >>>>>> >>><snip> >>>>>>Class-A implies _linear_, does it not? Or do we have a Larkin >>>>>>definition for today ?:-) >>>>>> >>>>> >>>>>The definition i have always heard is that it is conducting through the >>>>>whole cycle. Nothing about linearity. And that is one fougly non-linear >>>>>circuit. >>>> >>>>Only if you want it to be. It can be designed to be a nice smooth >>>>class A oscillator with precise automatic gain control that servoes >>>>oscillation amplitude to almost exactly 2*Vcc, with a low TC. Not bad >>>>for one transistor. >>>> >>>>John >>> >>>So post that version instead. >> >>I did, several days ago. >> >>ftp://jjlarkin.lmi.net/LC_YDx.gif > >No way sport, that is running deep class C. >> >>And I described it long before that. >> >>ftp://jjlarkin.lmi.net/Ships_Bell.JPG >> >>I can't help it if people keep over-driving it, and then complaining >>that it's over-driven. >> >>John > >The output is reasonable like a proper TC oscillator, but it is running >class C. Amusingly, but not surprisingly, the "nudge the swing" class-C version has the best spectral purity :-) ...Jim Thompson -- | James E.Thompson, CTO | mens | | Analog Innovations, Inc. | et | | Analog/Mixed-Signal ASIC's and Discrete Systems | manus | | Phoenix, Arizona 85048 Skype: Contacts Only | | | Voice:(480)460-2350 Fax: Available upon request | Brass Rat | | E-mail Icon at http://www.analog-innovations.com | 1962 | The only thing bipartisan in this country is hypocrisy
From: John Larkin on 16 Jun 2010 23:02 On Wed, 16 Jun 2010 19:15:30 -0700, "JosephKK"<quiettechblue(a)yahoo.com> wrote: >On Tue, 15 Jun 2010 20:45:37 -0700, John Larkin ><jjlarkin(a)highNOTlandTHIStechnologyPART.com> wrote: > >>On Tue, 15 Jun 2010 20:36:11 -0700, >>"JosephKK"<quiettechblue(a)yahoo.com> wrote: >> >>>On Mon, 14 Jun 2010 22:18:22 -0700, John Larkin >>><jjlarkin(a)highNOTlandTHIStechnologyPART.com> wrote: >>> >>>>On Mon, 14 Jun 2010 22:06:53 -0700, >>>>"JosephKK"<quiettechblue(a)yahoo.com> wrote: >>>> >>>>>On Mon, 14 Jun 2010 11:15:00 -0700, Jim Thompson >>>>><To-Email-Use-The-Envelope-Icon(a)On-My-Web-Site.com> wrote: >>>>> >>>>>>On Mon, 14 Jun 2010 10:50:58 -0700 (PDT), dagmargoodboat(a)yahoo.com >>>>>>wrote: >>>>>> >>><snip> >>>>>>Class-A implies _linear_, does it not? Or do we have a Larkin >>>>>>definition for today ?:-) >>>>>> >>>>> >>>>>The definition i have always heard is that it is conducting through the >>>>>whole cycle. Nothing about linearity. And that is one fougly non-linear >>>>>circuit. >>>> >>>>Only if you want it to be. It can be designed to be a nice smooth >>>>class A oscillator with precise automatic gain control that servoes >>>>oscillation amplitude to almost exactly 2*Vcc, with a low TC. Not bad >>>>for one transistor. >>>> >>>>John >>> >>>So post that version instead. >> >>I did, several days ago. >> >>ftp://jjlarkin.lmi.net/LC_YDx.gif > >No way sport, that is running deep class C. It is not. Simulate it and look at the whole cycle. Pay attention to the directions of the various currents. The pic above is zoomed up on the small interval, about 50 us, when the collector swings below the base. That's when the AGC happens, as charge is pulled out of the base capacitor and transistor bias, and transconductance, are servoed down. In fact, the drive into the tank is sustained over the whole rest of the cycle. The emitter current is a nice smooth curve and it doesn't cut off at the opposite peak of the cycle. One reason the amplitude is so predictable and stable is that it's NOT running "class C." Try it. Note especially the waveform at the base. >> >>And I described it long before that. >> >>ftp://jjlarkin.lmi.net/Ships_Bell.JPG >> >>I can't help it if people keep over-driving it, and then complaining >>that it's over-driven. >> >>John > >The output is reasonable like a proper TC oscillator, but it is running >class C. No. The gain mechanism is active through almost the whole cycle. But the naming of "class A" versus "class B" is a ham-radio sort of thing. It doesn't explain what the circuit is actually doing. The circuit doesn't care what letter you call it. I don't either. John
From: Jim Thompson on 16 Jun 2010 23:05 On Wed, 16 Jun 2010 20:02:05 -0700, John Larkin <jjlarkin(a)highNOTlandTHIStechnologyPART.com> wrote: >On Wed, 16 Jun 2010 19:15:30 -0700, >"JosephKK"<quiettechblue(a)yahoo.com> wrote: > >>On Tue, 15 Jun 2010 20:45:37 -0700, John Larkin >><jjlarkin(a)highNOTlandTHIStechnologyPART.com> wrote: >> >>>On Tue, 15 Jun 2010 20:36:11 -0700, >>>"JosephKK"<quiettechblue(a)yahoo.com> wrote: >>> >>>>On Mon, 14 Jun 2010 22:18:22 -0700, John Larkin >>>><jjlarkin(a)highNOTlandTHIStechnologyPART.com> wrote: >>>> >>>>>On Mon, 14 Jun 2010 22:06:53 -0700, >>>>>"JosephKK"<quiettechblue(a)yahoo.com> wrote: >>>>> >>>>>>On Mon, 14 Jun 2010 11:15:00 -0700, Jim Thompson >>>>>><To-Email-Use-The-Envelope-Icon(a)On-My-Web-Site.com> wrote: >>>>>> >>>>>>>On Mon, 14 Jun 2010 10:50:58 -0700 (PDT), dagmargoodboat(a)yahoo.com >>>>>>>wrote: >>>>>>> >>>><snip> >>>>>>>Class-A implies _linear_, does it not? Or do we have a Larkin >>>>>>>definition for today ?:-) >>>>>>> >>>>>> >>>>>>The definition i have always heard is that it is conducting through the >>>>>>whole cycle. Nothing about linearity. And that is one fougly non-linear >>>>>>circuit. >>>>> >>>>>Only if you want it to be. It can be designed to be a nice smooth >>>>>class A oscillator with precise automatic gain control that servoes >>>>>oscillation amplitude to almost exactly 2*Vcc, with a low TC. Not bad >>>>>for one transistor. >>>>> >>>>>John >>>> >>>>So post that version instead. >>> >>>I did, several days ago. >>> >>>ftp://jjlarkin.lmi.net/LC_YDx.gif >> >>No way sport, that is running deep class C. > >It is not. Simulate it and look at the whole cycle. Pay attention to >the directions of the various currents. > >The pic above is zoomed up on the small interval, about 50 us, when >the collector swings below the base. That's when the AGC happens, as >charge is pulled out of the base capacitor and transistor bias, and >transconductance, are servoed down. In fact, the drive into the tank >is sustained over the whole rest of the cycle. The emitter current is >a nice smooth curve and it doesn't cut off at the opposite peak of the >cycle. > >One reason the amplitude is so predictable and stable is that it's NOT >running "class C." > >Try it. Note especially the waveform at the base. > >>> >>>And I described it long before that. >>> >>>ftp://jjlarkin.lmi.net/Ships_Bell.JPG >>> >>>I can't help it if people keep over-driving it, and then complaining >>>that it's over-driven. >>> >>>John >> >>The output is reasonable like a proper TC oscillator, but it is running >>class C. > >No. The gain mechanism is active through almost the whole cycle. But >the naming of "class A" versus "class B" is a ham-radio sort of thing. >It doesn't explain what the circuit is actually doing. The circuit >doesn't care what letter you call it. I don't either. > >John > Single point declaration: WRONG! Young bucks proceed at your own peril. ...Jim Thompson -- | James E.Thompson, CTO | mens | | Analog Innovations, Inc. | et | | Analog/Mixed-Signal ASIC's and Discrete Systems | manus | | Phoenix, Arizona 85048 Skype: Contacts Only | | | Voice:(480)460-2350 Fax: Available upon request | Brass Rat | | E-mail Icon at http://www.analog-innovations.com | 1962 | The only thing bipartisan in this country is hypocrisy
From: Phil Hobbs on 17 Jun 2010 00:21
John Larkin wrote: > On Wed, 16 Jun 2010 19:15:30 -0700, > "JosephKK"<quiettechblue(a)yahoo.com> wrote: > >> On Tue, 15 Jun 2010 20:45:37 -0700, John Larkin >> <jjlarkin(a)highNOTlandTHIStechnologyPART.com> wrote: >> >>> On Tue, 15 Jun 2010 20:36:11 -0700, >>> "JosephKK"<quiettechblue(a)yahoo.com> wrote: >>> >>>> On Mon, 14 Jun 2010 22:18:22 -0700, John Larkin >>>> <jjlarkin(a)highNOTlandTHIStechnologyPART.com> wrote: >>>> >>>>> On Mon, 14 Jun 2010 22:06:53 -0700, >>>>> "JosephKK"<quiettechblue(a)yahoo.com> wrote: >>>>> >>>>>> On Mon, 14 Jun 2010 11:15:00 -0700, Jim Thompson >>>>>> <To-Email-Use-The-Envelope-Icon(a)On-My-Web-Site.com> wrote: >>>>>> >>>>>>> On Mon, 14 Jun 2010 10:50:58 -0700 (PDT), dagmargoodboat(a)yahoo.com >>>>>>> wrote: >>>>>>> >>>> <snip> >>>>>>> Class-A implies _linear_, does it not? Or do we have a Larkin >>>>>>> definition for today ?:-) >>>>>>> >>>>>> The definition i have always heard is that it is conducting through the >>>>>> whole cycle. Nothing about linearity. And that is one fougly non-linear >>>>>> circuit. >>>>> Only if you want it to be. It can be designed to be a nice smooth >>>>> class A oscillator with precise automatic gain control that servoes >>>>> oscillation amplitude to almost exactly 2*Vcc, with a low TC. Not bad >>>>> for one transistor. >>>>> >>>>> John >>>> So post that version instead. >>> I did, several days ago. >>> >>> ftp://jjlarkin.lmi.net/LC_YDx.gif >> No way sport, that is running deep class C. > > It is not. Simulate it and look at the whole cycle. Pay attention to > the directions of the various currents. > > The pic above is zoomed up on the small interval, about 50 us, when > the collector swings below the base. That's when the AGC happens, as > charge is pulled out of the base capacitor and transistor bias, and > transconductance, are servoed down. In fact, the drive into the tank > is sustained over the whole rest of the cycle. The emitter current is > a nice smooth curve and it doesn't cut off at the opposite peak of the > cycle. > > One reason the amplitude is so predictable and stable is that it's NOT > running "class C." > > Try it. Note especially the waveform at the base. > >>> And I described it long before that. >>> >>> ftp://jjlarkin.lmi.net/Ships_Bell.JPG >>> >>> I can't help it if people keep over-driving it, and then complaining >>> that it's over-driven. >>> >>> John >> The output is reasonable like a proper TC oscillator, but it is running >> class C. > > No. The gain mechanism is active through almost the whole cycle. But > the naming of "class A" versus "class B" is a ham-radio sort of thing. > It doesn't explain what the circuit is actually doing. The circuit > doesn't care what letter you call it. I don't either. > > John > > It's a cute circuit, but letting the BJT saturate causes horrible close-in phase noise. Cutoff is a much better behaved self-limiting mechanism than saturation, if you can't use separate AGC. Cheers Phil Hobbs -- Dr Philip C D Hobbs Principal ElectroOptical Innovations 55 Orchard Rd Briarcliff Manor NY 10510 845-480-2058 hobbs at electrooptical dot net http://electrooptical.net |