Op amp dirty signal.

C

Chris

Guest
How can i clean this signal?


http://chrispol.ath.cx:8080/opamp.jpg
http://chrispol.ath.cx:8080/wave.jpg
 
"Chris" <chrispol@videotron.ca> wrote in message
news:yIHsd.1818$IZ2.185192@wagner.videotron.net...
How can i clean this signal?


http://chrispol.ath.cx:8080/opamp.jpg
http://chrispol.ath.cx:8080/wave.jpg
Click to expand...
Where is your scope ground WRT to scoped signal?
Is the power supply well filtered?
Are the opamps bypassed?
What is the timebase setting?
What is the amplitude setting?
What is the coupling?
What does the input look like?
 
Chris wrote:
How can i clean this signal?


http://chrispol.ath.cx:8080/opamp.jpg
http://chrispol.ath.cx:8080/wave.jpg
Click to expand...
Try a capacitor across R3, value 100pf to 10000pf depending on value of R3
and desired upper frequency limit.
--
ciao Ban
Bordighera, Italy
 
Input looked the same ,. well turns out it's an bad wall socket,
realised this when i checked my probe on the scope and got a little jolt
moved it all off to another socket and a nice signlan added a small cap
filttered it right down :)


Lord Garth wrote:

"Chris" <chrispol@videotron.ca> wrote in message
news:yIHsd.1818$IZ2.185192@wagner.videotron.net...

How can i clean this signal?


http://chrispol.ath.cx:8080/opamp.jpg
http://chrispol.ath.cx:8080/wave.jpg


Where is your scope ground WRT to scoped signal?
Is the power supply well filtered?
Are the opamps bypassed?
What is the timebase setting?
What is the amplitude setting?
What is the coupling?
What does the input look like?
Click to expand...
 
small cap, ceramic? about how small?


Thanks

stratus46@yahoo.com wrote:

peterken wrote:

"Chris" <chrispol@videotron.ca> wrote in message
news:yIHsd.1818$IZ2.185192@wagner.videotron.net...

How can i clean this signal?


http://chrispol.ath.cx:8080/opamp.jpg
http://chrispol.ath.cx:8080/wave.jpg


It often helps to "decouple" outputs from their loads using small

resistors,

especially if the loads have a capacitive component.
Often opamps begin oscillating caused by this component.
The small resistors used will cause a small voltage drop which will

be

compensated by the opamp itself, so operation remains identical.

for IC1(A) (less needed here, but might help)
- small resistor (say 100e) from pin 1 to feedback junction
- small resistor (say 100e) from feedback junction to pin 2
(cut direct connection of course)
- small cap directly from pin1 to pin2
for IC1(D) (needed if load (out1) has a capacitive characteristic)
- small resistor (say 100e) from pin 14 to feedback junction
- small cap directly from pin14 to pin 13
for IC1(B) (needed if load (out2) has a capacitive characteristic)
- small resistor (say 100e) from pin 7 to feedback junction
- small resistor (say 100e) from feedback junction to pin 6
(cut direct connection of course)
- small cap directly from pin7 to pin6
for IC1(C) (needed if load (out3) has a capacitive characteristic)
- small resistor (say 100e) from pin 8 to feedback junction
- small resistor from feedback junction to pin 9 (cut direct

connection of

course)
- small cap directly from pin 8 to pin 9

principle:
(see drawing in notepad using fixed font)

|\
-----|+\
| \-+-/\/\-+--
| / | |
+-|-/ === |
| |/ === |
| | |
|______+_/\/\-+


Gee, your schematic looks just fine with the fixed font in this entry
window. Don't ya just love how people 'fix' things?
GG
Click to expand...
 
"Chris" <chrispol@videotron.ca> wrote in message
news:yIHsd.1818$IZ2.185192@wagner.videotron.net...
How can i clean this signal?


http://chrispol.ath.cx:8080/opamp.jpg
http://chrispol.ath.cx:8080/wave.jpg
Click to expand...

It often helps to "decouple" outputs from their loads using small resistors,
especially if the loads have a capacitive component.
Often opamps begin oscillating caused by this component.
The small resistors used will cause a small voltage drop which will be
compensated by the opamp itself, so operation remains identical.

for IC1(A) (less needed here, but might help)
- small resistor (say 100e) from pin 1 to feedback junction
- small resistor (say 100e) from feedback junction to pin 2
(cut direct connection of course)
- small cap directly from pin1 to pin2
for IC1(D) (needed if load (out1) has a capacitive characteristic)
- small resistor (say 100e) from pin 14 to feedback junction
- small cap directly from pin14 to pin 13
for IC1(B) (needed if load (out2) has a capacitive characteristic)
- small resistor (say 100e) from pin 7 to feedback junction
- small resistor (say 100e) from feedback junction to pin 6
(cut direct connection of course)
- small cap directly from pin7 to pin6
for IC1(C) (needed if load (out3) has a capacitive characteristic)
- small resistor (say 100e) from pin 8 to feedback junction
- small resistor from feedback junction to pin 9 (cut direct connection of
course)
- small cap directly from pin 8 to pin 9

principle:
(see drawing in notepad using fixed font)

|\
-----|+\
| \-+-/\/\-+--
| / | |
+-|-/ === |
| |/ === |
| | |
|______+_/\/\-+
 
peterken wrote:
"Chris" <chrispol@videotron.ca> wrote in message
news:yIHsd.1818$IZ2.185192@wagner.videotron.net...
How can i clean this signal?


http://chrispol.ath.cx:8080/opamp.jpg
http://chrispol.ath.cx:8080/wave.jpg


It often helps to "decouple" outputs from their loads using small
resistors,
especially if the loads have a capacitive component.
Often opamps begin oscillating caused by this component.
The small resistors used will cause a small voltage drop which will
be
compensated by the opamp itself, so operation remains identical.

for IC1(A) (less needed here, but might help)
- small resistor (say 100e) from pin 1 to feedback junction
- small resistor (say 100e) from feedback junction to pin 2
(cut direct connection of course)
- small cap directly from pin1 to pin2
for IC1(D) (needed if load (out1) has a capacitive characteristic)
- small resistor (say 100e) from pin 14 to feedback junction
- small cap directly from pin14 to pin 13
for IC1(B) (needed if load (out2) has a capacitive characteristic)
- small resistor (say 100e) from pin 7 to feedback junction
- small resistor (say 100e) from feedback junction to pin 6
(cut direct connection of course)
- small cap directly from pin7 to pin6
for IC1(C) (needed if load (out3) has a capacitive characteristic)
- small resistor (say 100e) from pin 8 to feedback junction
- small resistor from feedback junction to pin 9 (cut direct
connection of
course)
- small cap directly from pin 8 to pin 9

principle:
(see drawing in notepad using fixed font)

|\
-----|+\
| \-+-/\/\-+--
| / | |
+-|-/ === |
| |/ === |
| | |
|______+_/\/\-+
Click to expand...
Gee, your schematic looks just fine with the fixed font in this entry
window. Don't ya just love how people 'fix' things?
GG
 
"Chris" <chrispol@videotron.ca> wrote in message
news:mYutd.22467$Ou1.1424367@weber.videotron.net...
small cap, ceramic? about how small?


Thanks

stratus46@yahoo.com wrote:

peterken wrote:

"Chris" <chrispol@videotron.ca> wrote in message
news:yIHsd.1818$IZ2.185192@wagner.videotron.net...

How can i clean this signal?


http://chrispol.ath.cx:8080/opamp.jpg
http://chrispol.ath.cx:8080/wave.jpg


It often helps to "decouple" outputs from their loads using small

resistors,

especially if the loads have a capacitive component.
Often opamps begin oscillating caused by this component.
The small resistors used will cause a small voltage drop which will

be

compensated by the opamp itself, so operation remains identical.

for IC1(A) (less needed here, but might help)
- small resistor (say 100e) from pin 1 to feedback junction
- small resistor (say 100e) from feedback junction to pin 2
(cut direct connection of course)
- small cap directly from pin1 to pin2
for IC1(D) (needed if load (out1) has a capacitive characteristic)
- small resistor (say 100e) from pin 14 to feedback junction
- small cap directly from pin14 to pin 13
for IC1(B) (needed if load (out2) has a capacitive characteristic)
- small resistor (say 100e) from pin 7 to feedback junction
- small resistor (say 100e) from feedback junction to pin 6
(cut direct connection of course)
- small cap directly from pin7 to pin6
for IC1(C) (needed if load (out3) has a capacitive characteristic)
- small resistor (say 100e) from pin 8 to feedback junction
- small resistor from feedback junction to pin 9 (cut direct

connection of

course)
- small cap directly from pin 8 to pin 9

principle:
(see drawing in notepad using fixed font)

|\
-----|+\
| \-+-/\/\-+--
| / | |
+-|-/ === |
| |/ === |
| | |
|______+_/\/\-+


Gee, your schematic looks just fine with the fixed font in this entry
window. Don't ya just love how people 'fix' things?
GG
Click to expand...
depends on the highest frequency you want passing through the circuit of
course since it's a filtering circuit
I'd begin with say 1nF and go up by decade while looking at the signal on
your scope until the output satisfies your needs
 
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