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-   -   One Last Attempt at Discrete Opamp in DIP8 Footprint (https://www.diyaudio.com/forums/analog-line-level/337484-attempt-discrete-opamp-dip8-footprint.html)

EUVL 4th May 2019 08:01 PM

One Last Attempt at Discrete Opamp in DIP8 Footprint
 
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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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EUVL 4th May 2019 08:03 PM

Opamp Topologies
 
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Firstly a discussion about different basic opamp topologies.


Patrick

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EUVL 4th May 2019 08:06 PM

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


Patrick

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EUVL 4th May 2019 08:13 PM

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


Patrick

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EUVL 4th May 2019 08:18 PM

J-797
 
1 Attachment(s)
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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Mark Tillotson 4th May 2019 10:19 PM

Time to move to pre-biased transistor arrays in SOT1216 package perhaps? :)
https://assets.nexperia.com/document...eet/PQMD10.pdf

EUVL 5th May 2019 02:09 AM

If I don't care about hfe linearity, perhaps.


Patrick

6L6 5th May 2019 03:11 AM

Absolutely fantastic!

Looking forward to seeing more about this!

EUVL 5th May 2019 04:50 AM

What more would you like to see ?

:)


Patrick

basreflex 5th May 2019 06:28 AM

what about BJT classB complementary outputs?


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