amplify 40kHz audio signal using TL082: first two stages are

[Fred Bartoli]

"Larry Brasfield" <donotspam_larry_brasfield@hotmail.com> a écrit dans le
message de news:W%G_d.37$VW.623@news.uswest.net...

(And before you reply, you may want to
consider Fred Bartoli's post of 12:16 today
where he makes a point relevant to your
"snipe". He appears to know more about
real noise analysis than you do.)

Well, I won't be so sure...


--
Thanks,
Fred.

 

[lemonjuice]

I agree on this, guy. This is really basic electronics, but this is
still
too advanced for you, like it seems some 1.35V low voltage voltage
amplifiers.

You appear to be a bit out of juice, lemonhead.

LOL . Youu should stop hoping that I'd answer a delinquent like a
Bartholi!

 

[John Woodgate]

I read in sci.electronics.design that Larry Brasfield <donotspam_larry_b
rasfield@hotmail.com> wrote (in <W%G_d.37$VW.623@news.uswest.net&gt about
'amplify 40kHz audio signal using TL082: first two stages are fine, but
high noise from the third stage', on Fri, 18 Mar 2005:

I am unable to replicate your 115 dB figure.

I get 94 dB voltage gain from the OP's 50 x 50 x 20. Anything more
complex makes my brain 'urt.

Am I turning into an analogue Genome?
--
Regards, John Woodgate, OOO - Own Opinions Only.
There are two sides to every question, except
'What is a Moebius strip?'
http://www.jmwa.demon.co.uk Also see http://www.isce.org.uk

 

[John Woodgate]

I read in sci.electronics.design that Fred Bartoli <fred._canxxxel_this_
bartoli@RemoveThatAlso_free.fr_AndThisToo> wrote (in <423b398b$0$22858$6
36a15ce@news.free.fr&gt about 'amplify 40kHz audio signal using TL082:
first two stages are fine, but high noise from the third stage', on Fri,
18 Mar 2005:

Now, you build an amplifier, isn't it?

Only in France and Wales.
--
Regards, John Woodgate, OOO - Own Opinions Only.
There are two sides to every question, except
'What is a Moebius strip?'
http://www.jmwa.demon.co.uk Also see http://www.isce.org.uk

 

[lemonjuice]

(And before you reply, you may want to
consider Fred Bartoli's post of 12:16 today
where he makes a point relevant to your
"snipe".

I checked it. All wrong.

 

[Larry Brasfield]

"lemonjuice" <exskimos@anonymous.to> wrote in message
news:1111180812.330626.262910@f14g2000cwb.googlegroups.com...

(And before you reply, you may want to
consider Fred Bartoli's post of 12:16 today
where he makes a point relevant to your
"snipe".

I checked it. All wrong.

Not all wrong at all. His fundamental point, which
you would do well to learn, is that the noise output
of cascaded amplifiers with moderate gain will be
dominated by the input noise of the first stage.

This principle, (in a more general form that applies
to any set of gains), is known as the "Friis formula"
or "Friis noise equation". I suggest you look it up,
study a bit, then extend an apology to Mr. Bartoli.

--
--Larry Brasfield
email: donotspam_larry_brasfield@hotmail.com
Above views may belong only to me.

 

[Fred Bloggs]

Larry Brasfield wrote:
[...snip drivel...]

As usual we all see you doing a bunch of pussy factoid arithmetic, but
what have you accomplished? You have hit a brick wall- absolutely no
plan whatsoever to define or fix the noise induced threshold crossing
problem. And that's because you don't know how...

 

[Fred Bloggs]

Larry Brasfield wrote:

I went as far as was needed to explain the reported
observation that brought the OP here.

Nah- you went as far as you could- and that wasn't to far...

Going beyond
simple would be a disservice at this point, for reasons
you could figure out yourself if you thought about the
OP's situation rather than your own aggrandizement.

Yeah- right- bullsh_t.

[...snip drivel from a drowning rodent...]

 

[Fred Bloggs]

Larry Brasfield wrote:

What other noise analysis do you believe is
relevant to what the OP reports seeing?

I am not here to educate you...

[...snip drivel from drowning rodent...]

 

[John Woodgate]

I read in sci.electronics.design that Fred Bartoli <fred._canxxxel_this_
bartoli@RemoveThatAlso_free.fr_AndThisToo> wrote (in <423c21a6$0$22865$6
36a15ce@news.free.fr&gt about 'amplify 40kHz audio signal using TL082:
first two stages are fine, but high noise from the third stage', on Sat,
19 Mar 2005:

"John Woodgate" <jmw@jmwa.demon.contraspam.yuk> a écrit dans le message de
news:l93$RRBoU0OCFwEw@jmwa.demon.co.uk...
I read in sci.electronics.design that Fred Bartoli <fred._canxxxel_this_
bartoli@RemoveThatAlso_free.fr_AndThisToo> wrote (in <423b398b$0$22858$6
36a15ce@news.free.fr&gt about 'amplify 40kHz audio signal using TL082:
first two stages are fine, but high noise from the third stage', on Fri,
18 Mar 2005:

Now, you build an amplifier, isn't it?

Only in France and Wales.

???

Sorry John, but I miss the point.
Probably some more shade in my knowledge of english.


The appended 'isn't it' is characteristic of French ('n'est-ce pas?')

and Welsh English (not Welsh Welsh) spoken language. Note that the 'it'
in 'isn't it' has no referent in the preceding sentence, as in 'He's a
really tall man, isn't it?'
--
Regards, John Woodgate, OOO - Own Opinions Only.
There are two sides to every question, except
'What is a Moebius strip?'
http://www.jmwa.demon.co.uk Also see http://www.isce.org.uk

 

[Larry Brasfield]

This has been converted, via a process I will call the DERF transform [1].
This elision process conforms to accepted Usenet quoting practise with
the exception that elided text is replaced by "[DERF]" and, where needed
for grammaticality, short sequences with a '[]' pair are inserted.

[1. Application of a filter removing Dreck, Extraneousness, Redundancy, Foolishness.]

"Fred Bloggs" <nospam@nospam.com> wrote in
message news:423B8503.6000903@nospam.com...

Larry Brasfield wrote:

I went as far as was needed to explain the reported
observation that brought the OP here.

Nah- you went as far as you could- and that wasn't to far...

Clever, Fred. Assuming you meant "too far", you seem
to have understood my earlier made point that complicating
the analysis beyond what significantly affects the result is
a disservice to the OP. I do try to avoid "too far".

As for " went as far as could", yes, you've gotten it.
I operated within that constraint except for my analysis of
the dreaded "open JFET op-amp" effect. I hope you
were able to follow that and enjoy the chuckle I did.
(However, I doubt both clauses of that conjuction.)

Going beyond
simple would be a disservice at this point, for reasons
you could figure out yourself if you thought about the
OP's situation rather than your own aggrandizement.

Yeah- right- bullsh_t.

Woops, I guess you were unable to understand that point.
Was there any particular part of it that you had trouble
with, or is the whole concept of engineering approximation
something you find difficult to grasp? Maybe you are
unaware of the Friis formula and its implications here.
I admit to puzzlement in light of the awe you seem to induce
in some folks here. Of course, that also puzzles me.

[DERF]

(Well, 1 down, 2 to go. I'm disappointed, having
missed that "challenge" you mentioned elsewhere.)

--
--Larry Brasfield
email: donotspam_larry_brasfield@hotmail.com
Above views may belong only to me.

 

[Larry Brasfield]

This has been converted, via a process I will call the DERF transform [1].
This elision process conforms to accepted Usenet quoting practise with
the exception that elided text is replaced by "[DERF]" and, where needed
for grammaticality, short sequences with a '[]' pair are inserted.

[1. Application of a filter removing Dreck, Extraneousness, Redundancy, Foolishness.]

"Fred Bloggs" <nospam@nospam.com> wrote in
message news:423B855B.4000407@nospam.com...

Larry Brasfield wrote:

What other noise analysis do you believe is
relevant to what the OP reports seeing?

I am not here to educate you...

I agree. However, your pretense that there is some
additional relevant noise analysis that you cannot
divulge for anti-educational reasons is educational
itself. Unfortunately, it's not an education I need.

[DERF]

(Well, 2 down, 1 to go. I'm disappointed, having
missed that "challenge" you mentioned elsewhere. I
guess, given your veracity, it must be coming up.)

--
Larry Brasfield
email: donotspam_larry_brasfield@hotmail.com
Above views may belong only to me.

 

[Larry Brasfield]

"Fred Bloggs" <nospam@nospam.com> wrote in message
news:423B8454.5060005@nospam.com...
[drivel snipped]

As usual we all see you doing a bunch of pussy factoid arithmetic, but what have you accomplished? You have hit a brick wall-
absolutely no plan whatsoever to define or fix the noise induced threshold crossing problem.

As far as I can see, the OP is an electronics student
who simply needed to become aware of how noise
ultimately limits receiver performance. I offered to
review his detector and improve his preamp once
he shows the detector and provides a little more
data about the transducer. I have also indicated
that some sort pre-detection filter is likely to help,
but that depends on his existing detector as well as
the transducer bandwidth and what he is trying to
accomplish, yet to be known. I do not expect that
you can understand why that is a sensible approach,
but most normal folks would have no such problem.

And that's because you don't know how...

Another thin air production. I've built sonar detectors
that I doubt you could understand without my help, or
the help of some other competent analog designer.

(Well, that's all 3 posts alleged to contain a "challenge".
Maybe my news server dropped a post, as happens
once in a great while. I'll check Google news and see
if I can locate your "challenge" and post my answer,
one way or another. But I'm disappointed so far.)

--
--Larry Brasfield
email: donotspam_larry_brasfield@hotmail.com
Above views may belong only to me.

 

[Fred Bloggs]

Larry Brasfield wrote:
[...snip drowning rodent drool...]

Where's your workup on the 40kHz amplifier thread, fairy loudmouth boy?
Can't go any further with 4KTRB and some other simple-minded trash? We
are not surprised, windbag. You are one little superficial and worthless
moron.

 

[Fred Bloggs]

Larry Brasfield wrote:
[...snip a bunch of hot air from pretentious little pussy...]

Where's your workup on the 40kHz amplifier thread, fairy loudmouth boy?
Can't go any further with 4KTRB and some other simple-minded trash? We
are not surprised, windbag. You are one little superficial and worthless
moron.

 

[Fred Bloggs]

Larry Brasfield wrote:
[...yawn...]
Where's your workup on the 40kHz amplifier thread, fairy loudmouth boy?
Can't go any further with 4KTRB and some other simple-minded trash? We
are not surprised, windbag. You are one little superficial and worthless
moron.

 

[Ken Smith]

In article <3EE_d.20028$Pz7.12231@newssvr13.news.prodigy.com>,
Joerg <notthisjoergsch@removethispacbell.net> wrote:

Hello Ken,

I hadn't thought of using an LC circuit for this case. At 40KHz it may
not be such abad idea.

An LC would be pretty easy at 40kHz. However, it depends on what the OP
wants to do. If he intends to do pulse echo with good range resolution
it needs to stay wideband.

It doesn't need to be truely wide band:

(1)
A burst of the 40KHz signal reflects off the far object and is received.
In the reciever, both the amplitude profile and the phase of individual
cycles can be used in the calculation.

So long as the amplitude profile is short enough in time that the timing
can be determined to within on cycle, the phase of the signal can be used
to fill in the digits below that. If the filter is reasonably stable, a
constant can be subtracted from the result to correct of its delay.

(2)
The 40KHz can be frequency modulated. The narrowness of the filter makes
the time between zero crossings change more slowly than in the transmitted
signal. A micro can look at the series of values of the period of the
signal. It can fit the numbers to a curve and determine when the curve
passed through a certain value. This will give a value that again is only
lated by a constant.

--
--
kensmith@rahul.net forging knowledge

 

[Pooh Bear]

for_idea wrote:

Dear friends,

I am making an ultrasound signal receiver. The transmitter and receiver
is apart from each other about 6 meters. The circuit is powered by a 9v
battery. I used three amplifiers from two TL082. The reference voltage
(about 4.5v) is generated from voltage divider (two 100k resisters in
series). All amplifiers are in inverting input mode. First and second
stages are configured as: 10k input resister and 500k feedback
resister. The signal output in the second stage is very good. However,
the signal from the third stage (input res.= 10k, output res. = 200k)
is significantly corrupted by noise. Please give me some advice to
clean up the amplified signal.

To begin with, the inverting ampliifer configuration you're using is
inherently noisier than non-inverting.

You have a gain of 50 x 50 x 20 = 5000 x or 74dB. Any input noise will be
amplified by that amount ( plus you need to factor in the additional
thermal noise from your inverting configuration ). It's hardly surprising
it's noisy !

The input noise of the TL082 isn't great to begin with - try the TL072 for
a quick, simple improvement for example.

So - to summarise. Use the *non-inverting* configuration for lower noise.
Use quieter op-amps.


Graham

 

[Larry Brasfield]

The DERF tranform, applied here, is described earlier in this thread.

"Fred Bloggs" <nospam@nospam.com> wrote in
message news:423C52CA.5020500@nospam.com...

?

Asked and answered. You may like repeating
yourself, but I find it too boring for words.

[DERF]
--
--Larry Brasfield
email: donotspam_larry_brasfield@hotmail.com
Above views may belong only to me.

 

[Larry Brasfield]

This has been converted, via a process I will call the DERF transform [1].
This elision process conforms to accepted Usenet quoting practise with
the exception that elided text is replaced by "[DERF]" and, where needed
for grammaticality, short sequences with a '[]' pair are inserted.

[1. Application of a filter removing Dreck, Extraneousness, Redundancy, Foolishness.]

"Fred Bloggs" <nospam@nospam.com> wrote in
message news:423C5317.4030703@nospam.com...

[DERF]

Amazingly, all 4 of the DERF criteria applied to that elision.

Fred, can you find anything worthwhile to post about?
With your probing and powerful intellect, surely you
can do better than we've been seeing lately.

--
--Larry Brasfield
email: donotspam_larry_brasfield@hotmail.com
Above views may belong only to me.