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Analog Line Level Preamplifiers , Passive Pre-amps, Crossovers, etc.

One Last Attempt at Discrete Opamp in DIP8 Footprint
One Last Attempt at Discrete Opamp in DIP8 Footprint
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Old 4th May 2019, 08:01 PM   #1
EUVL is offline EUVL  Europe
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Default One Last Attempt at Discrete Opamp in DIP8 Footprint

As the film title says, “Never say never”.
So perhaps I should not have used the word last attempt.

Anyhow, a DC-stable discrete opamp in a DIP-8 Footprint has remained unfinished business for me, despite a few attempts over the years.
The previous failures were largely due to DC offsets and unity-gain stability.

In the last 18 months, after much contemplation, a renewed effort was made to take on this challenge one last time.
This time with much better success, apparently.
Nothing really ground breaking. But that is also not where the difficulty lies.


Patrick

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Attached Images
File Type: jpg 190225 SOPA Top.JPG (244.2 KB, 962 views)
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Old 4th May 2019, 08:03 PM   #2
EUVL is offline EUVL  Europe
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Default Opamp Topologies

Firstly a discussion about different basic opamp topologies.


Patrick

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File Type: pdf Discrete Opamp Topologies 2019.pdf (534.6 KB, 329 views)
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Old 4th May 2019, 08:06 PM   #3
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Default SOPA

The first topology that was built and tested, as Dual version.


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Attached Images
File Type: jpg 190226 SOPD #2 Side Trimmed.JPG (172.7 KB, 1000 views)
Attached Files
File Type: pdf Thermally Symmetrical Discrete Opamp SOPA.pdf (496.9 KB, 154 views)
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Old 4th May 2019, 08:13 PM   #4
EUVL is offline EUVL  Europe
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Default JCOPA

The 2nd topology was based on the JC Pro-1.
Just for fun, this one is SOIC8 compatible.


Patrick

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Attached Images
File Type: jpg 190225 JCOPS #1 Front.JPG (250.9 KB, 874 views)
Attached Files
File Type: pdf Dual LTP Discrete Opamp JCOPA.pdf (487.3 KB, 175 views)
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Old 4th May 2019, 08:18 PM   #5
EUVL is offline EUVL  Europe
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Default J-797

The last (but not least) has just been built today and shown here on test fixture.
Distortion measurements still have to be made.
But all basic functional tests were according to expectation.


Patrick

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File Type: jpg 190504 J797 #1R+L Test.JPG (315.3 KB, 870 views)
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Old 4th May 2019, 10:19 PM   #6
Mark Tillotson is offline Mark Tillotson
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Time to move to pre-biased transistor arrays in SOT1216 package perhaps?
https://assets.nexperia.com/document...eet/PQMD10.pdf
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Old 5th May 2019, 02:09 AM   #7
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If I don't care about hfe linearity, perhaps.


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Old 5th May 2019, 03:11 AM   #8
6L6 is offline 6L6  United States
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One Last Attempt at Discrete Opamp in DIP8 Footprint
Absolutely fantastic!

Looking forward to seeing more about this!
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Old 5th May 2019, 04:50 AM   #9
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What more would you like to see ?




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Old 5th May 2019, 06:28 AM   #10
basreflex is offline basreflex  Spain
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what about BJT classB complementary outputs?
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