for example, LM324
http://www.st.com/stonline/books/pdf/docs/4797.pdf
the data sheet states a differential voltage of as much as 32 volts is
permissible.
But in the diagram it looks like at about 15 or 20 volts input
differential the b/e junctions on one of the inputs would go into
reverse conduction.
Do I misunderstand or do they use protection circuitry not shown in
the diagram.

gearhead wrote:
> for example, LM324
> http://www.st.com/stonline/books/pdf/docs/4797.pdf
> the data sheet states a differential voltage of as much as 32 volts
is
> permissible.
> But in the diagram it looks like at about 15 or 20 volts input
> differential the b/e junctions on one of the inputs would go into
> reverse conduction.
> Do I misunderstand or do they use protection circuitry not shown in
> the diagram.

Read all the info. You'll see note 1 "Neither of the input voltages
must exceed the magnitude of Vcc+ and Vcc-"

Are you referring to the diodes from both inputs to the power supply
rails? Those would certainly be the 'limiting' factor.

GG

gearhead wrote:
> for example, LM324
> http://www.st.com/stonline/books/pdf/docs/4797.pdf
> the data sheet states a differential voltage of as much as 32 volts is
> permissible.
> But in the diagram it looks like at about 15 or 20 volts input
> differential the b/e junctions on one of the inputs would go into
> reverse conduction.
> Do I misunderstand or do they use protection circuitry not shown in
> the diagram.

I think the PNP input transistors have been doped to produce
base emitter reverse break down voltage exceeding the
maximum supply voltage rating. This compromise reduces the
performance possible with these transistors, but makes using
this opamp with open loop inputs, very easy.

Jamie wrote:
..
> And also, if I remember correctly, the LM324 is one of those op-amps
> that has a discontinued output. meaning, when the follower outputs
> cross the zero path or near it, there is no minimum bias for both rails
> being applied to maintain constant current. In a way, this is good in
> equipment that wants to save on energy when it's used in things like
> OSC's, voltage comparator etc..

....Including all sorts of DC and low frequency (not audio)
signal applications, and audio if you can arrange the load
to keep only one side of the output totem pole conducting
throughout the waveform (or if distortion is not very
important, like alarm buzzers or telephone quality voice).

Jamie wrote:

> And also, if I remember correctly, the LM324 is one of those op-amps
> that has a discontinued output. meaning, when the follower outputs
> cross the zero path or near it, there is no minimum bias for both rails
> being applied to maintain constant current. In a way, this is good in
> equipment that wants to save on energy when it's used in things like
> OSC's, voltage comparator etc..

More use of weird and wacky nomenclature from Jamie the Clueless.

Did you mean 'the output stage has zero quiescent current' ? In which case I
believe the answer is yes, or 'close to zero'.

I fail to see why you introduced this, since it has nothing to do with the OP's
question.

Graham

Jamie wrote:

> Eeyore wrote:
> > Jamie wrote:
> >
> >> And also, if I remember correctly, the LM324 is one of those op-amps
> >>that has a discontinued output. meaning, when the follower outputs
> >> cross the zero path or near it, there is no minimum bias for both rails
> >>being applied to maintain constant current. In a way, this is good in
> >>equipment that wants to save on energy when it's used in things like
> >>OSC's, voltage comparator etc..
> >
> > More use of weird and wacky nomenclature from Jamie the Clueless.
> >
> > Did you mean 'the output stage has zero quiescent current' ? In which case I
> > believe the answer is yes, or 'close to zero'.
> >
> > I fail to see why you introduced this, since it has nothing to do with the OP's
> > question.
>
>
> Ok idiot, Most people that come here and read are entry level or minor
> techs, they don't need to see the book thrown at them.

Yet that is exactly what YOU do.

My answers are normally short and succinct and keep to topic, whereas yours are
rambling, off-topic and full of errors including 'using the wrong words'.

Graham

On Fri, 31 Aug 2007 22:16:23 -0400, Jamie
<jamie_ka1lpa_not_valid_after_ka1lpa_@charter.net> wrote:

>Eeyore wrote:
>
>>
>> Jamie wrote:
>>
>>
>>> And also, if I remember correctly, the LM324 is one of those op-amps
>>>that has a discontinued output. meaning, when the follower outputs
>>> cross the zero path or near it, there is no minimum bias for both rails
>>>being applied to maintain constant current. In a way, this is good in
>>>equipment that wants to save on energy when it's used in things like
>>>OSC's, voltage comparator etc..
>>
>>
>> More use of weird and wacky nomenclature from Jamie the Clueless.
>>
>> Did you mean 'the output stage has zero quiescent current' ? In which case I
>> believe the answer is yes, or 'close to zero'.
>>
>> I fail to see why you introduced this, since it has nothing to do with the OP's
>> question.
>>
>> Graham
>>
>
> Ok idiot, Most people that come here and read are entry level or minor
>techs, they don't need to see the book thrown at them. What a jerk you
>are.

He's been sinking into snarling-mad-dog, insult everybody, Roy L Fuchs
mode for some time now. Just another sad insult-bot usenut.

John

Jamie wrote:

> Let me tell you something, I put my son through Electronic Engineering College.

How big of you !

I learnt a huge amount of electronic knowledge even before I went to Uni/college. Nor
did I have anyone to 'put me through' either.


> My son is a very intelligent kid how ever, having instructors
> throwing the lingo at him like that when he is really trying to get a
> grasp on what the instructor is trying to convey made it hard. Not just him but
> many other of his class mates.

That's because many university lecturers are clueless idiots who are totally divorced
from the real world and real world ways of doing things. I had the same problem at
UCL.

There is however no excuse not to know what 'quiesent current' means since it's a
very widely used term to describe a very important issue. Instead you rambled on
about ......

" a discontinued output. meaning, when the follower outputs cross the zero path or
near it, there is no minimum bias for both rails
being applied to maintain constant current. In a way, this is good in equipment that
wants to save on energy when it's used in things like OSC's, voltage comparator etc..
"

Which is a perfect example of the very thing you were criticising. It also makes no
damn sense.

Graham

Jamie wrote:

> using a feed back cap stopped that how ever, it also added to the
> miller effect problems.

Miller effect in an op-amp circuit ?

Once again, you're using technical terms in an inapproriate way.

Graham

John Larkin wrote:

> Jamie wrote:
> >Eeyore wrote:
> >> Jamie wrote:
> >>
> >>> And also, if I remember correctly, the LM324 is one of those op-amps
> >>>that has a discontinued output. meaning, when the follower outputs
> >>> cross the zero path or near it, there is no minimum bias for both rails
> >>>being applied to maintain constant current. In a way, this is good in
> >>>equipment that wants to save on energy when it's used in things like
> >>>OSC's, voltage comparator etc..
> >>
> >>
> >> More use of weird and wacky nomenclature from Jamie the Clueless.
> >>
> >> Did you mean 'the output stage has zero quiescent current' ? In which case I
> >> believe the answer is yes, or 'close to zero'.
> >>
> >> I fail to see why you introduced this, since it has nothing to do with the OP's
> >> question.
> >>
> >> Graham
> >>
> >
> > Ok idiot, Most people that come here and read are entry level or minor
> >techs, they don't need to see the book thrown at them. What a jerk you
> >are.
>
> He's been sinking into snarling-mad-dog, insult everybody, Roy L Fuchs
> mode for some time now. Just another sad insult-bot usenut.

I suggest you read my posts HERE !

I only snarl at ineducable American idiots.

Jamie IS a clueless twat and posts idiotic nonsense that never answers the OP's
questions.

Graham

On Aug 31, 3:45 pm, John Popelish <jpopel...@rica.net> wrote:
> gearhead wrote:
> > for example, LM324
> >http://www.st.com/stonline/books/pdf/docs/4797.pdf
> > the data sheet states a differential voltage of as much as 32 volts is
> > permissible.
> > But in the diagram it looks like at about 15 or 20 volts input
> > differential the b/e junctions on one of the inputs would go into
> > reverse conduction.
> > Do I misunderstand or do they use protection circuitry not shown in
> > the diagram.
>
> I think the PNP input transistors have been doped to produce
> base emitter reverse break down voltage exceeding the
> maximum supply voltage rating. This compromise reduces the
> performance possible with these transistors, but makes using
> this opamp with open loop inputs, very easy.

That makes sense.