John Larkin's LC oscillator
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From: Joel Koltner on 14 Jun 2010 23:55 "Jim Thompson" <To-Email-Use-The-Envelope-Icon(a)On-My-Web-Site.com> wrote in message news:pptd16hna6lpujah03dsd55ob299mccd0j(a)4ax.com... > On Mon, 14 Jun 2010 23:38:55 -0400, Phil Hobbs >>PITA alert. Why not stick to electronics instead of pissing contests? > > Sure. As soon as Larkin sticks to facts instead of BS. Otherwise it's > open season. OK, but why bother going hunting in the first place? Even if you "bag" John, is mounting his head over your fireplace's mantle really going to give you much enjoyment? :-)
From: Jim Thompson on 14 Jun 2010 23:58 On Mon, 14 Jun 2010 20:55:50 -0700, "Joel Koltner" <zapwireDASHgroups(a)yahoo.com> wrote: >"Jim Thompson" <To-Email-Use-The-Envelope-Icon(a)On-My-Web-Site.com> wrote in >message news:pptd16hna6lpujah03dsd55ob299mccd0j(a)4ax.com... >> On Mon, 14 Jun 2010 23:38:55 -0400, Phil Hobbs >>>PITA alert. Why not stick to electronics instead of pissing contests? >> >> Sure. As soon as Larkin sticks to facts instead of BS. Otherwise it's >> open season. > >OK, but why bother going hunting in the first place? Even if you "bag" John, >is mounting his head over your fireplace's mantle really going to give you >much enjoyment? :-) John can call it off any time. But I doubt that he will. Thus I will ultimately "win" :-) ...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 15 Jun 2010 00:24 On 6/14/2010 11:46 PM, Jim Thompson wrote: > On Mon, 14 Jun 2010 23:38:55 -0400, Phil Hobbs > <pcdhSpamMeSenseless(a)electrooptical.net> wrote: > >> On 6/14/2010 11:04 AM, Jim Thompson wrote: >>> On Mon, 14 Jun 2010 07:37:20 -0400, JW<none(a)dev.null> wrote: >>> >>>> On Sat, 12 Jun 2010 12:03:24 -0500 "krw(a)att.bizzzzzzzzzzzz" >>>> <krw(a)att.bizzzzzzzzzzzz> wrote in Message id: >>>> <lcf7165d59talqrbbsejrdgv947dsre53r(a)4ax.com>: >>>> >>>>> AlwaysWrong shifting goal posts when he's wrong, as always. >>>>> >>> [snip] >>> >>> Like Larkin ?:-) >>> >>> ...Jim Thompson >> >> PITA alert. Why not stick to electronics instead of pissing contests? >> >> Cheers >> >> Phil Hobbs > > Sure. As soon as Larkin sticks to facts instead of BS. Otherwise it's > open season. > > BTW, Are you an independent observer, or are you still on his payroll > ?:-) > > ...Jim Thompson Amusing. Not. I have a lot of respect for John as an engineer, as I have for you, Win, and a number of other contributors here--but none of my customers has posted here that I've seen. I'm just bored with pissing contests, is all, and other people's pissing contests are even more boring than mine. If any further proof were needed that enginering in the US is in trouble, the fact that good people like you have nothing better to do than one-up each other would be fairly persuasive evidence. 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
From: JosephKK on 15 Jun 2010 01:06 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: > >>On Jun 14, 12:08 pm, Jim Thompson <To-Email-Use-The-Envelope-I...(a)On- >>My-Web-Site.com> wrote: >>> On Mon, 14 Jun 2010 09:49:09 -0700 (PDT), dagmargoodb...(a)yahoo.com >>> wrote: >[snip] >>> >>> > Vcc = +5v >>> > --+--------------+------+-- >>> > | | | >>> > | | .-. >>> > | | | | e.s.r. = 1 ohm >>> > | | | | >>> > | | '-' >>> > | | | >>> > | | |_ || >>> > | | _)|| >>> > .-. --- L1a _)|| >>> > Rb | | C1 --- 1mH _)|| >>> > 47k | | 1uF | _)|| >>> > '-' | _)|| >>> > | | *| || >>> > | '---+--' || >>> > | R1 D1 | || >>> > | 220r schottky | || >>> > +--/\/\/----|>]----+ || >>> > | | || >>> > | .------------' || >>> > | |/ || >>> > +---| Q1 || >>> > | |>. 2n3904 || >>> > | | * || >>> > C2 --- +----------------. || >>> > 1uF --- | L1b _)|| >>> > | | 100nH _)|| >>> > | | | >>> > === | === >>> > | >>> > '--------------------> 5KHz output >>> >>> >Cheers, >>> >James Arthur >>> >>> [snip LTspice Schematic] >>> >>> James, How can you call it "class-A" when the emitter current is >>> _not_linear_, _not_linear_, _not_linear_, _not_linear_ !! >> >>True, the emitter current isn't linear, but it is continuous and non- >>zero, so I call that "class-A." >> >> >>> All you've done is use a Schottky bypassing the C-B junction... >>> otherwise it's identical. >> >>That makes a big difference. It prevents Q1 saturating and from >>conducting b-c. And, without it Q1 conducts in reverse mode during >>negative peaks, making the i(c) not just discontinuous, but reversing >>in direction. That loads the tank, obviously. > >"Obviously"? Q1 doesn't conduct in reverse with your values, but no >Schottky... the current is always out of the emitter... though it does >get awfully close to zero: -376uA and -12.5mA peak. > >> >>> I liken such oscillators to how you push your kid on a swing set. >>> Giving a "nudge" every cycle. >> >>That's exactly how I think of them too. A "nudge" each cycle (short >>conduction cycle) is what I did first. I call that "class-C." >> >>> To be "class-A" you'd need to sit upon the top bars and _continuously_ >>> push and pull the ropes. >> >>Or you can pull continuously, harder at some times, not as hard at >>others. That gives the swing position a d.c. bias, but is otherwise >>the same, yes? > >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.
From: John Larkin on 15 Jun 2010 01:18
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: >> >>>On Jun 14, 12:08�pm, Jim Thompson <To-Email-Use-The-Envelope-I...(a)On- >>>My-Web-Site.com> wrote: >>>> On Mon, 14 Jun 2010 09:49:09 -0700 (PDT), dagmargoodb...(a)yahoo.com >>>> wrote: >>[snip] >>>> >>>> > � � � � Vcc = +5v >>>> > � �--+--------------+------+-- >>>> > � � �| � � � � � � �| � � �| >>>> > � � �| � � � � � � �| � � .-. >>>> > � � �| � � � � � � �| � � | | e.s.r. = 1 ohm >>>> > � � �| � � � � � � �| � � | | >>>> > � � �| � � � � � � �| � � '-' >>>> > � � �| � � � � � � �| � � �| >>>> > � � �| � � � � � � �| � � �|_ || >>>> > � � �| � � � � � � �| � � � _)|| >>>> > � � .-. � � � � � �--- �L1a _)|| >>>> > Rb �| | � � � � C1 --- �1mH _)|| >>>> > 47k | | � � � � 1uF | � � � _)|| >>>> > � � '-' � � � � � � | � � � _)|| >>>> > � � �| � � � � � � �| � � *| �|| >>>> > � � �| � � � � � � �'---+--' �|| >>>> > � � �| � �R1 � � D1 � � | � � || >>>> > � � �| � 220r �schottky | � � || >>>> > � � �+--/\/\/----|>]----+ � � || >>>> > � � �| � � � � � � � � �| � � || >>>> > � � �| � � .------------' � � || >>>> > � � �| � |/ � � � � � � � � � || >>>> > � � �+---| � �Q1 � � � � � � �|| >>>> > � � �| � |>. 2n3904 � � � � � || >>>> > � � �| � � | � � � � � � � * �|| >>>> > �C2 --- � �+----------------. || >>>> > 1uF --- � �| � � � � � L1b �_)|| >>>> > � � �| � � | � � � � 100nH �_)|| >>>> > � � �| � � | � � � � � � � | >>>> > � � === � �| � � � � � � �=== >>>> > � � � � � �| >>>> > � � � � � �'--------------------> 5KHz output >>>> >>>> >Cheers, >>>> >James Arthur >>>> >>>> [snip LTspice Schematic] >>>> >>>> James, �How can you call it "class-A" when the emitter current is >>>> _not_linear_, _not_linear_, _not_linear_, _not_linear_ !! >>> >>>True, the emitter current isn't linear, but it is continuous and non- >>>zero, so I call that "class-A." >>> >>> >>>> All you've done is use a Schottky bypassing the C-B junction... >>>> otherwise it's identical. >>> >>>That makes a big difference. It prevents Q1 saturating and from >>>conducting b-c. And, without it Q1 conducts in reverse mode during >>>negative peaks, making the i(c) not just discontinuous, but reversing >>>in direction. That loads the tank, obviously. >> >>"Obviously"? Q1 doesn't conduct in reverse with your values, but no >>Schottky... the current is always out of the emitter... though it does >>get awfully close to zero: -376uA and -12.5mA peak. >> >>> >>>> I liken such oscillators to how you push your kid on a swing set. >>>> Giving a "nudge" every cycle. >>> >>>That's exactly how I think of them too. A "nudge" each cycle (short >>>conduction cycle) is what I did first. I call that "class-C." >>> >>>> To be "class-A" you'd need to sit upon the top bars and _continuously_ >>>> push and pull the ropes. >>> >>>Or you can pull continuously, harder at some times, not as hard at >>>others. That gives the swing position a d.c. bias, but is otherwise >>>the same, yes? >> >>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 |