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Datasheet Jargon Translation Required

Started by Cursitor Doom July 11, 2021
On Tue, 13 Jul 2021 06:59:07 -0700, jlarkin@highlandsniptechnology.com
wrote:

>On Tue, 13 Jul 2021 08:51:31 +0100, Martin Brown ><'''newspam'''@nonad.co.uk> wrote: > >>On 13/07/2021 01:21, John Larkin wrote: >>> On Tue, 13 Jul 2021 10:01:49 +1000, Clifford Heath >>> <no.spam@please.net> wrote: >>> >>>> On 13/7/21 6:51 am, John Larkin wrote: >> >>>>> No use trying to help you. >>>> >>>> Please stop trying to educate it then. This is a creature who still >>>> thinks resistors must have leads. Fully Neanderthal... >>> >>> Poles are jargon. >> >>Poles come from complex analysis representing zeroes in the denominator >>of a transfer function. Zeroes in the numerator are just called zeros. >>Electronic engineers have adopted the language of mathematicians here. > >A dynamic mic driving an inverting opamp gets much more interesting. >Kind of a tent village.
Sounds like the kind of excitement that is best avoided by using the non-inverting input and living with whatever tiny increase in distortion results. No change to compensation. -- Best regards, Spehro Pefhany
On Tue, 13 Jul 2021 10:35:44 -0400, Spehro Pefhany
<speffSNIP@interlogDOTyou.knowwhat> wrote:

>On Tue, 13 Jul 2021 06:59:07 -0700, jlarkin@highlandsniptechnology.com >wrote: > >>On Tue, 13 Jul 2021 08:51:31 +0100, Martin Brown >><'''newspam'''@nonad.co.uk> wrote: >> >>>On 13/07/2021 01:21, John Larkin wrote: >>>> On Tue, 13 Jul 2021 10:01:49 +1000, Clifford Heath >>>> <no.spam@please.net> wrote: >>>> >>>>> On 13/7/21 6:51 am, John Larkin wrote: >>> >>>>>> No use trying to help you. >>>>> >>>>> Please stop trying to educate it then. This is a creature who still >>>>> thinks resistors must have leads. Fully Neanderthal... >>>> >>>> Poles are jargon. >>> >>>Poles come from complex analysis representing zeroes in the denominator >>>of a transfer function. Zeroes in the numerator are just called zeros. >>>Electronic engineers have adopted the language of mathematicians here. >> >>A dynamic mic driving an inverting opamp gets much more interesting. >>Kind of a tent village. > >Sounds like the kind of excitement that is best avoided by using the >non-inverting input and living with whatever tiny increase in >distortion results. No change to compensation.
Exactly. Inverting has all sorts of interesting issues. Mic loading. Noise. DC offset. -- John Larkin Highland Technology, Inc The best designs are necessarily accidental.
On Mon, 12 Jul 2021 13:51:36 -0700, John Larkin
<jlarkin@highland_atwork_technology.com> wrote:

>On Mon, 12 Jul 2021 21:27:09 +0100, Cursitor Doom <cd@nowhere.com> >wrote: > >>On Mon, 12 Jul 2021 21:11:29 +0100, Cursitor Doom <cd@nowhere.com> >>wrote: >> >>>On Sun, 11 Jul 2021 18:18:45 -0700, jlarkin@highlandsniptechnology.com >>>wrote: >>> >>>>On Sun, 11 Jul 2021 23:59:07 +0100, Cursitor Doom <cd@nowhere.com> >>>>wrote: >>>> >>>>>On Sun, 11 Jul 2021 13:58:12 -0700, jlarkin@highlandsniptechnology.com >>>>>wrote: >>>>> >>>>>>On Sun, 11 Jul 2021 19:51:59 +0100, Cursitor Doom <cd@nowhere.com> >>>>>>wrote: >>>>>> >>>>>>>On Sun, 11 Jul 2021 11:04:57 -0700, jlarkin@highlandsniptechnology.com >>>>>>>wrote: >>>>>>>> >>>>>>>>A pole is basically a frequency rolloff corner, a resistor and a >>>>>>>>capacitor as a lowpass filter. The corner frequency is 1/(2*pi*R*C) >>>>>>>> >>>>>>>>The term actually refers to LaPlace transforms and complex plane plots >>>>>>>>and stuff. >>>>>>>> >>>>>>>>Opamps usually have an internal pole in the 10 Hz sort of range. >>>>>>>> >>>>>>>>A pole has phase shift, 45 degrees lag at the corner frequency, >>>>>>>>creeping up towards 90 at high frequencies. >>>>>>>> >>>>>>>>Two poles in a loop approaches 180 degrees shift, so negative feedback >>>>>>>>becomes positive and things can get unstable. Your feedback network >>>>>>>>might create a significant pole. >>>>>>>> >>>>>>>>Got a circuit sketch? You can Spice this. >>>>>>> >>>>>>>I'm just following page 16 of this document (diagram 2 at the bottom >>>>>>>of the page). Couldn't be simpler - or so I thought til they started >>>>>>>on about feedback poles. >>>>>>> >>>>>>>https://www.ti.com/lit/ds/symlink/lf356-mil.pdf >>>>>>> >>>>>>>>The part about supply decoupling and pcb capacitance is usually no big >>>>>>>>deal. Data sheets like to be alarmist about that stuff. >>>>>>> >>>>>>>Is that what the C1 'virtual capacitor' between the inverting and >>>>>>>non-inverting inputs is all about? >>>>>> >>>>>>That 3 pF is internal to the opamp. PCB pads are typically a fraction >>>>>>of a pF. >>>>>> >>>>>>1/16" thick FR4 is around 15 pF per square inch, so a typical pad is >>>>>>pretty small. Vias are usually a fraction of a pF too. >>>>>> >>>>>>If R1||R2 were, say, 1K, and C1 were 3 pF, the feedback pole would be >>>>>>tau=3 ns, corner frequency around 50 MHz, assuming pi=6. That's way >>>>>>above the freq where this opamp is out of gain, so it's OK. But if the >>>>>>resistance were 100K, there could be trouble. >>>>> >>>>>Seems I needn't worry, then. I'm only going to be using this as the >>>>>first stage of an amp for a dynamic microphone and the 20hz-20khz >>>>>audio band is way too low for tiny stray capacitances to matter. There >>>>>may be other pitfalls, but stray caps isn't something I need to worry >>>>>about here. >>>> >>>>Post a sketch of the circuit. Words don't tell the story. >>> >>>It's on page 16 of the datasheet I linked to (diagram 2). Really >>>couldn't be any simpler; just a case of observing the layout >>>directions and chosing the right support components for the op-amp >>>itself. >>> >>>https://www.ti.com/lit/ds/symlink/lf356-mil.pdf >> >>Or "figure 27" as they also show it as. Bottom of page 16 anyway. > >No use trying to help you.
But you already have! As has Speff and a couple of other worthy individuals. This is one tiny project I'd rather others didn't design for me. Spoils all the fun! :-D
On Tue, 13 Jul 2021 18:46:44 +0100, Cursitor Doom <cd@nowhere.com>
wrote:

>On Mon, 12 Jul 2021 13:51:36 -0700, John Larkin ><jlarkin@highland_atwork_technology.com> wrote: > >>On Mon, 12 Jul 2021 21:27:09 +0100, Cursitor Doom <cd@nowhere.com> >>wrote: >> >>>On Mon, 12 Jul 2021 21:11:29 +0100, Cursitor Doom <cd@nowhere.com> >>>wrote: >>> >>>>On Sun, 11 Jul 2021 18:18:45 -0700, jlarkin@highlandsniptechnology.com >>>>wrote: >>>> >>>>>On Sun, 11 Jul 2021 23:59:07 +0100, Cursitor Doom <cd@nowhere.com> >>>>>wrote: >>>>> >>>>>>On Sun, 11 Jul 2021 13:58:12 -0700, jlarkin@highlandsniptechnology.com >>>>>>wrote: >>>>>> >>>>>>>On Sun, 11 Jul 2021 19:51:59 +0100, Cursitor Doom <cd@nowhere.com> >>>>>>>wrote: >>>>>>> >>>>>>>>On Sun, 11 Jul 2021 11:04:57 -0700, jlarkin@highlandsniptechnology.com >>>>>>>>wrote: >>>>>>>>> >>>>>>>>>A pole is basically a frequency rolloff corner, a resistor and a >>>>>>>>>capacitor as a lowpass filter. The corner frequency is 1/(2*pi*R*C) >>>>>>>>> >>>>>>>>>The term actually refers to LaPlace transforms and complex plane plots >>>>>>>>>and stuff. >>>>>>>>> >>>>>>>>>Opamps usually have an internal pole in the 10 Hz sort of range. >>>>>>>>> >>>>>>>>>A pole has phase shift, 45 degrees lag at the corner frequency, >>>>>>>>>creeping up towards 90 at high frequencies. >>>>>>>>> >>>>>>>>>Two poles in a loop approaches 180 degrees shift, so negative feedback >>>>>>>>>becomes positive and things can get unstable. Your feedback network >>>>>>>>>might create a significant pole. >>>>>>>>> >>>>>>>>>Got a circuit sketch? You can Spice this. >>>>>>>> >>>>>>>>I'm just following page 16 of this document (diagram 2 at the bottom >>>>>>>>of the page). Couldn't be simpler - or so I thought til they started >>>>>>>>on about feedback poles. >>>>>>>> >>>>>>>>https://www.ti.com/lit/ds/symlink/lf356-mil.pdf >>>>>>>> >>>>>>>>>The part about supply decoupling and pcb capacitance is usually no big >>>>>>>>>deal. Data sheets like to be alarmist about that stuff. >>>>>>>> >>>>>>>>Is that what the C1 'virtual capacitor' between the inverting and >>>>>>>>non-inverting inputs is all about? >>>>>>> >>>>>>>That 3 pF is internal to the opamp. PCB pads are typically a fraction >>>>>>>of a pF. >>>>>>> >>>>>>>1/16" thick FR4 is around 15 pF per square inch, so a typical pad is >>>>>>>pretty small. Vias are usually a fraction of a pF too. >>>>>>> >>>>>>>If R1||R2 were, say, 1K, and C1 were 3 pF, the feedback pole would be >>>>>>>tau=3 ns, corner frequency around 50 MHz, assuming pi=6. That's way >>>>>>>above the freq where this opamp is out of gain, so it's OK. But if the >>>>>>>resistance were 100K, there could be trouble. >>>>>> >>>>>>Seems I needn't worry, then. I'm only going to be using this as the >>>>>>first stage of an amp for a dynamic microphone and the 20hz-20khz >>>>>>audio band is way too low for tiny stray capacitances to matter. There >>>>>>may be other pitfalls, but stray caps isn't something I need to worry >>>>>>about here. >>>>> >>>>>Post a sketch of the circuit. Words don't tell the story. >>>> >>>>It's on page 16 of the datasheet I linked to (diagram 2). Really >>>>couldn't be any simpler; just a case of observing the layout >>>>directions and chosing the right support components for the op-amp >>>>itself. >>>> >>>>https://www.ti.com/lit/ds/symlink/lf356-mil.pdf >>> >>>Or "figure 27" as they also show it as. Bottom of page 16 anyway. >> >>No use trying to help you. > >But you already have! As has Speff and a couple of other worthy >individuals. This is one tiny project I'd rather others didn't design >for me. Spoils all the fun! :-D
If you won't post your schematic, then we can't have any fun!
On Tue, 13 Jul 2021 08:51:31 +0100, Martin Brown
<'''newspam'''@nonad.co.uk> wrote:

>On 13/07/2021 01:21, John Larkin wrote: >> On Tue, 13 Jul 2021 10:01:49 +1000, Clifford Heath >> <no.spam@please.net> wrote: >> >>> On 13/7/21 6:51 am, John Larkin wrote: > >>>> No use trying to help you. >>> >>> Please stop trying to educate it then. This is a creature who still >>> thinks resistors must have leads. Fully Neanderthal... >> >> Poles are jargon. > >Poles come from complex analysis representing zeroes in the denominator >of a transfer function. Zeroes in the numerator are just called zeros. >Electronic engineers have adopted the language of mathematicians here.
The LaPlace/pole/zero thing was academic formalism in the pre-computer age. I don't do that stuff any more... just Spice it. That fussy stuff was linear anyhow. The world isn't linear. My profs loved that sort of math. I don't think any of them actually designed anything. S-params and Smith charts are arguably similar relics of the graph paper and slide-rule days.
On Tue, 13 Jul 2021 12:23:24 -0700, John Larkin
<jlarkin@highland_atwork_technology.com> wrote:

>On Tue, 13 Jul 2021 18:46:44 +0100, Cursitor Doom <cd@nowhere.com> >wrote: > >>On Mon, 12 Jul 2021 13:51:36 -0700, John Larkin >><jlarkin@highland_atwork_technology.com> wrote: >> >>>On Mon, 12 Jul 2021 21:27:09 +0100, Cursitor Doom <cd@nowhere.com> >>>wrote: >>> >>>>On Mon, 12 Jul 2021 21:11:29 +0100, Cursitor Doom <cd@nowhere.com> >>>>wrote: >>>> >>>>>On Sun, 11 Jul 2021 18:18:45 -0700, jlarkin@highlandsniptechnology.com >>>>>wrote: >>>>> >>>>>>On Sun, 11 Jul 2021 23:59:07 +0100, Cursitor Doom <cd@nowhere.com> >>>>>>wrote: >>>>>> >>>>>>>On Sun, 11 Jul 2021 13:58:12 -0700, jlarkin@highlandsniptechnology.com >>>>>>>wrote: >>>>>>> >>>>>>>>On Sun, 11 Jul 2021 19:51:59 +0100, Cursitor Doom <cd@nowhere.com> >>>>>>>>wrote: >>>>>>>> >>>>>>>>>On Sun, 11 Jul 2021 11:04:57 -0700, jlarkin@highlandsniptechnology.com >>>>>>>>>wrote: >>>>>>>>>> >>>>>>>>>>A pole is basically a frequency rolloff corner, a resistor and a >>>>>>>>>>capacitor as a lowpass filter. The corner frequency is 1/(2*pi*R*C) >>>>>>>>>> >>>>>>>>>>The term actually refers to LaPlace transforms and complex plane plots >>>>>>>>>>and stuff. >>>>>>>>>> >>>>>>>>>>Opamps usually have an internal pole in the 10 Hz sort of range. >>>>>>>>>> >>>>>>>>>>A pole has phase shift, 45 degrees lag at the corner frequency, >>>>>>>>>>creeping up towards 90 at high frequencies. >>>>>>>>>> >>>>>>>>>>Two poles in a loop approaches 180 degrees shift, so negative feedback >>>>>>>>>>becomes positive and things can get unstable. Your feedback network >>>>>>>>>>might create a significant pole. >>>>>>>>>> >>>>>>>>>>Got a circuit sketch? You can Spice this. >>>>>>>>> >>>>>>>>>I'm just following page 16 of this document (diagram 2 at the bottom >>>>>>>>>of the page). Couldn't be simpler - or so I thought til they started >>>>>>>>>on about feedback poles. >>>>>>>>> >>>>>>>>>https://www.ti.com/lit/ds/symlink/lf356-mil.pdf >>>>>>>>> >>>>>>>>>>The part about supply decoupling and pcb capacitance is usually no big >>>>>>>>>>deal. Data sheets like to be alarmist about that stuff. >>>>>>>>> >>>>>>>>>Is that what the C1 'virtual capacitor' between the inverting and >>>>>>>>>non-inverting inputs is all about? >>>>>>>> >>>>>>>>That 3 pF is internal to the opamp. PCB pads are typically a fraction >>>>>>>>of a pF. >>>>>>>> >>>>>>>>1/16" thick FR4 is around 15 pF per square inch, so a typical pad is >>>>>>>>pretty small. Vias are usually a fraction of a pF too. >>>>>>>> >>>>>>>>If R1||R2 were, say, 1K, and C1 were 3 pF, the feedback pole would be >>>>>>>>tau=3 ns, corner frequency around 50 MHz, assuming pi=6. That's way >>>>>>>>above the freq where this opamp is out of gain, so it's OK. But if the >>>>>>>>resistance were 100K, there could be trouble. >>>>>>> >>>>>>>Seems I needn't worry, then. I'm only going to be using this as the >>>>>>>first stage of an amp for a dynamic microphone and the 20hz-20khz >>>>>>>audio band is way too low for tiny stray capacitances to matter. There >>>>>>>may be other pitfalls, but stray caps isn't something I need to worry >>>>>>>about here. >>>>>> >>>>>>Post a sketch of the circuit. Words don't tell the story. >>>>> >>>>>It's on page 16 of the datasheet I linked to (diagram 2). Really >>>>>couldn't be any simpler; just a case of observing the layout >>>>>directions and chosing the right support components for the op-amp >>>>>itself. >>>>> >>>>>https://www.ti.com/lit/ds/symlink/lf356-mil.pdf >>>> >>>>Or "figure 27" as they also show it as. Bottom of page 16 anyway. >>> >>>No use trying to help you. >> >>But you already have! As has Speff and a couple of other worthy >>individuals. This is one tiny project I'd rather others didn't design >>for me. Spoils all the fun! :-D > >If you won't post your schematic, then we can't have any fun!
Are you unable to view the diagram at all? Remember those old programs we used to use on this group that generated ASCII art representations of schematics? Crude but effective and in the days when we had nothing else - Invaluable. So... what's the issue with the diagram I linked to?
On Tue, 13 Jul 2021 23:18:28 +0100, Cursitor Doom <cd@nowhere.com>
wrote:

>On Tue, 13 Jul 2021 12:23:24 -0700, John Larkin ><jlarkin@highland_atwork_technology.com> wrote: > >>On Tue, 13 Jul 2021 18:46:44 +0100, Cursitor Doom <cd@nowhere.com> >>wrote: >> >>>On Mon, 12 Jul 2021 13:51:36 -0700, John Larkin >>><jlarkin@highland_atwork_technology.com> wrote: >>> >>>>On Mon, 12 Jul 2021 21:27:09 +0100, Cursitor Doom <cd@nowhere.com> >>>>wrote: >>>> >>>>>On Mon, 12 Jul 2021 21:11:29 +0100, Cursitor Doom <cd@nowhere.com> >>>>>wrote: >>>>> >>>>>>On Sun, 11 Jul 2021 18:18:45 -0700, jlarkin@highlandsniptechnology.com >>>>>>wrote: >>>>>> >>>>>>>On Sun, 11 Jul 2021 23:59:07 +0100, Cursitor Doom <cd@nowhere.com> >>>>>>>wrote: >>>>>>> >>>>>>>>On Sun, 11 Jul 2021 13:58:12 -0700, jlarkin@highlandsniptechnology.com >>>>>>>>wrote: >>>>>>>> >>>>>>>>>On Sun, 11 Jul 2021 19:51:59 +0100, Cursitor Doom <cd@nowhere.com> >>>>>>>>>wrote: >>>>>>>>> >>>>>>>>>>On Sun, 11 Jul 2021 11:04:57 -0700, jlarkin@highlandsniptechnology.com >>>>>>>>>>wrote: >>>>>>>>>>> >>>>>>>>>>>A pole is basically a frequency rolloff corner, a resistor and a >>>>>>>>>>>capacitor as a lowpass filter. The corner frequency is 1/(2*pi*R*C) >>>>>>>>>>> >>>>>>>>>>>The term actually refers to LaPlace transforms and complex plane plots >>>>>>>>>>>and stuff. >>>>>>>>>>> >>>>>>>>>>>Opamps usually have an internal pole in the 10 Hz sort of range. >>>>>>>>>>> >>>>>>>>>>>A pole has phase shift, 45 degrees lag at the corner frequency, >>>>>>>>>>>creeping up towards 90 at high frequencies. >>>>>>>>>>> >>>>>>>>>>>Two poles in a loop approaches 180 degrees shift, so negative feedback >>>>>>>>>>>becomes positive and things can get unstable. Your feedback network >>>>>>>>>>>might create a significant pole. >>>>>>>>>>> >>>>>>>>>>>Got a circuit sketch? You can Spice this. >>>>>>>>>> >>>>>>>>>>I'm just following page 16 of this document (diagram 2 at the bottom >>>>>>>>>>of the page). Couldn't be simpler - or so I thought til they started >>>>>>>>>>on about feedback poles. >>>>>>>>>> >>>>>>>>>>https://www.ti.com/lit/ds/symlink/lf356-mil.pdf >>>>>>>>>> >>>>>>>>>>>The part about supply decoupling and pcb capacitance is usually no big >>>>>>>>>>>deal. Data sheets like to be alarmist about that stuff. >>>>>>>>>> >>>>>>>>>>Is that what the C1 'virtual capacitor' between the inverting and >>>>>>>>>>non-inverting inputs is all about? >>>>>>>>> >>>>>>>>>That 3 pF is internal to the opamp. PCB pads are typically a fraction >>>>>>>>>of a pF. >>>>>>>>> >>>>>>>>>1/16" thick FR4 is around 15 pF per square inch, so a typical pad is >>>>>>>>>pretty small. Vias are usually a fraction of a pF too. >>>>>>>>> >>>>>>>>>If R1||R2 were, say, 1K, and C1 were 3 pF, the feedback pole would be >>>>>>>>>tau=3 ns, corner frequency around 50 MHz, assuming pi=6. That's way >>>>>>>>>above the freq where this opamp is out of gain, so it's OK. But if the >>>>>>>>>resistance were 100K, there could be trouble. >>>>>>>> >>>>>>>>Seems I needn't worry, then. I'm only going to be using this as the >>>>>>>>first stage of an amp for a dynamic microphone and the 20hz-20khz >>>>>>>>audio band is way too low for tiny stray capacitances to matter. There >>>>>>>>may be other pitfalls, but stray caps isn't something I need to worry >>>>>>>>about here. >>>>>>> >>>>>>>Post a sketch of the circuit. Words don't tell the story. >>>>>> >>>>>>It's on page 16 of the datasheet I linked to (diagram 2). Really >>>>>>couldn't be any simpler; just a case of observing the layout >>>>>>directions and chosing the right support components for the op-amp >>>>>>itself. >>>>>> >>>>>>https://www.ti.com/lit/ds/symlink/lf356-mil.pdf >>>>> >>>>>Or "figure 27" as they also show it as. Bottom of page 16 anyway. >>>> >>>>No use trying to help you. >>> >>>But you already have! As has Speff and a couple of other worthy >>>individuals. This is one tiny project I'd rather others didn't design >>>for me. Spoils all the fun! :-D >> >>If you won't post your schematic, then we can't have any fun! > >Are you unable to view the diagram at all? Remember those old programs >we used to use on this group that generated ASCII art representations >of schematics? Crude but effective and in the days when we had nothing >else - Invaluable. > >So... what's the issue with the diagram I linked to?
The opamp data sheet? It isn't a microphone amplifier. But never mind.
On Wednesday, July 14, 2021 at 5:29:59 AM UTC+10, John Larkin wrote:
> On Tue, 13 Jul 2021 08:51:31 +0100, Martin Brown > <'''newspam'''@nonad.co.uk> wrote: > >On 13/07/2021 01:21, John Larkin wrote: > >> On Tue, 13 Jul 2021 10:01:49 +1000, Clifford Heath > >> <no....@please.net> wrote: > >> > >>> On 13/7/21 6:51 am, John Larkin wrote: > > > >>>> No use trying to help you. > >>> > >>> Please stop trying to educate it then. This is a creature who still > >>> thinks resistors must have leads. Fully Neanderthal... > >> > >> Poles are jargon. > > > >Poles come from complex analysis representing zeroes in the denominator > >of a transfer function. Zeroes in the numerator are just called zeros. > >Electronic engineers have adopted the language of mathematicians here. > > The LaPlace/pole/zero thing was academic formalism in the pre-computer > age. I don't do that stuff any more... just Spice it.
Of course you don't. Getting your head around the academic formalism lets you understand what's going on, and you don't do that.
> That fussy stuff was linear anyhow. The world isn't linear.
Most of us have noticed. The linear bits are easier to understand and manipulate, so they get more attention.
> My profs loved that sort of math. I don't think any of them actually designed anything.
Of course, since John Larkin doesn't actually understand what "design" involves, this isn't a useful observation.
> S-params and Smith charts are arguably similar relics of the graph paper and slide-rule days.
S-parameters have been around for a while, as have Smith charts. Visual representation of what's going on do help people develop an understanding of the processes involved, but John Larkin is happy to rely on Darwinian evolution to get him to circuits that work well enough to sell, even if he doesn't understand quite how they work. A computer is merely an bigger, faster more precise slide-rule and graph paper is a slower form of visual display. Chart recorders were the original data loggers. -- Bill Sloman, Sydney
On 13/07/2021 23:18, Cursitor Doom wrote:
> On Tue, 13 Jul 2021 12:23:24 -0700, John Larkin > <jlarkin@highland_atwork_technology.com> wrote: > >> On Tue, 13 Jul 2021 18:46:44 +0100, Cursitor Doom <cd@nowhere.com> >> wrote: >> >>> On Mon, 12 Jul 2021 13:51:36 -0700, John Larkin >>> <jlarkin@highland_atwork_technology.com> wrote: >>> >>>> On Mon, 12 Jul 2021 21:27:09 +0100, Cursitor Doom <cd@nowhere.com> >>>> wrote: >>>> >>>>> On Mon, 12 Jul 2021 21:11:29 +0100, Cursitor Doom <cd@nowhere.com> >>>>> wrote: >>>>> >>>>>> On Sun, 11 Jul 2021 18:18:45 -0700, jlarkin@highlandsniptechnology.com >>>>>> wrote: >>>>>>
>>>>>>> Post a sketch of the circuit. Words don't tell the story. >>>>>> >>>>>> It's on page 16 of the datasheet I linked to (diagram 2). Really >>>>>> couldn't be any simpler; just a case of observing the layout >>>>>> directions and chosing the right support components for the op-amp >>>>>> itself. >>>>>> >>>>>> https://www.ti.com/lit/ds/symlink/lf356-mil.pdf >>>>> >>>>> Or "figure 27" as they also show it as. Bottom of page 16 anyway. >>>> >>>> No use trying to help you. >>> >>> But you already have! As has Speff and a couple of other worthy >>> individuals. This is one tiny project I'd rather others didn't design >>> for me. Spoils all the fun! :-D >> >> If you won't post your schematic, then we can't have any fun! > > Are you unable to view the diagram at all? Remember those old programs > we used to use on this group that generated ASCII art representations > of schematics? Crude but effective and in the days when we had nothing > else - Invaluable. > > So... what's the issue with the diagram I linked to?
It just shows how to use the chip as a simple inverting amplifier without having it oscillate like crazy due to stray capacitance at the input. Which part of make R1*C1=R2*C2 do you not understand? The real practical difficulty is matching your dynamic microphone to the "ideal" amplifier for lowest possible distortion and maximum signal. John is asking to see that part - not the gain block after it. -- Regards, Martin Brown
"the concepts "male" and "female" are essentially social constructions" (Bill Sloman)

Bozo the Clown...

-- 
Anthony William Sloman <bill.sloman@ieee.org> wrote:

> X-Received: by 2002:a05:620a:1137:: with SMTP id p23mr8042866qkk.490.1626234270528; Tue, 13 Jul 2021 20:44:30 -0700 (PDT) > X-Received: by 2002:a05:620a:1920:: with SMTP id bj32mr7845129qkb.406.1626234270359; Tue, 13 Jul 2021 20:44:30 -0700 (PDT) > Path: eternal-september.org!reader02.eternal-september.org!news.mixmin.net!proxad.net!feeder1-2.proxad.net!209.85.160.216.MISMATCH!news-out.google.com!nntp.google.com!postnews.google.com!google-groups.googlegroups.com!not-for-mail > Newsgroups: sci.electronics.design > Date: Tue, 13 Jul 2021 20:44:30 -0700 (PDT) > In-Reply-To: <22qregtrghu9f6kpbgigiop4o9d69j854u@4ax.com> > Injection-Info: google-groups.googlegroups.com; posting-host=14.202.161.14; posting-account=SJ46pgoAAABuUDuHc5uDiXN30ATE-zi- > NNTP-Posting-Host: 14.202.161.14 > References: <c4fmegdjmkh50e0ffqehk5jnjodrp0q6no@4ax.com> <2hlmeghcv621nf2uo3v8vfon4mp67nim8b@4ax.com> <gjtmeg9jk5urm7u3sf1mt40p95qvjmj3g1@4ax.com> <k26negddb7lqo8khc7mf6h1gkdtu8kslbi@4ax.com> <2c8pegp6tqorfngurpqq4pa3odas4s32m9@4ax.com> <fb9peg1j6ku6biroh4pvc2t4p1qvfm0tnh@4ax.com> <upapeglm5au67bikmi0rsplqg15keev2nh@4ax.com> <169130b88b5f6eb5$1$1356503$70dd7a6b@news.thecubenet.com> <i2npegpvofrr5lnf88bmie3jijde09jcjr@4ax.com> <scjgm3$1r8g$1@gioia.aioe.org> <22qregtrghu9f6kpbgigiop4o9d69j854u@4ax.com> > User-Agent: G2/1.0 > MIME-Version: 1.0 > Message-ID: <329f0961-6df4-4b3e-84f1-5cd5a06c7787n@googlegroups.com> > Subject: Re: Datasheet Jargon Translation Required > From: Anthony William Sloman <bill.sloman@ieee.org> > Injection-Date: Wed, 14 Jul 2021 03:44:30 +0000 > Content-Type: text/plain; charset="UTF-8" > Content-Transfer-Encoding: quoted-printable > Xref: reader02.eternal-september.org sci.electronics.design:637012 > > On Wednesday, July 14, 2021 at 5:29:59 AM UTC+10, John Larkin wrote: >> On Tue, 13 Jul 2021 08:51:31 +0100, Martin Brown >> <'''newspam'''@nonad.co.uk> wrote: >> >On 13/07/2021 01:21, John Larkin wrote: >> >> On Tue, 13 Jul 2021 10:01:49 +1000, Clifford Heath >> >> <no....@please.net> wrote: >> >> >> >>> On 13/7/21 6:51 am, John Larkin wrote: >> > >> >>>> No use trying to help you. >> >>> >> >>> Please stop trying to educate it then. This is a creature who still > >> >>> thinks resistors must have leads. Fully Neanderthal... >> >> >> >> Poles are jargon. >> > >> >Poles come from complex analysis representing zeroes in the denominator > >> >of a transfer function. Zeroes in the numerator are just called zeros. > >> >Electronic engineers have adopted the language of mathematicians here. >> >> The LaPlace/pole/zero thing was academic formalism in the pre-computer >> age. I don't do that stuff any more... just Spice it. > > Of course you don't. Getting your head around the academic formalism lets you understand what's going on, and you don't do that. > >> That fussy stuff was linear anyhow. The world isn't linear. > > Most of us have noticed. The linear bits are easier to understand and manipulate, so they get more attention. > >> My profs loved that sort of math. I don't think any of them actually des > igned anything. > > Of course, since John Larkin doesn't actually understand what "design" involves, this isn't a useful observation. > >> S-params and Smith charts are arguably similar relics of the graph paper > and slide-rule days. > > S-parameters have been around for a while, as have Smith charts. Visual representation of what's going on do help people develop an understanding of the processes involved, but John Larkin is happy to rely on Darwinian evolution to get him to circuits that work well enough to sell, even if he doesn't understand quite how they work. > > A computer is merely an bigger, faster more precise slide-rule and graph paper is a slower form of visual display. Chart recorders were the original data loggers. > > -- > Bill Sloman, Sydney > >