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Old 23rd April 2012, 07:05 PM   #981
generg is offline generg  Germany
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yes Zen Mod, I will do a better one!

but there is no fault? or is there one?
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Old 23rd April 2012, 07:06 PM   #982
NYCOne is offline NYCOne  United States
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Quote:
Originally Posted by generg View Post
I hope this "handmade" picture helps...

I hope there are no faults, I am in a hurry to go to a party in Heidelberg.....46 years Abitur celebration......two days....

see you later on monday...
I'm just tuning back into this - do you tie back to "-Reference" or Ground in your diagram. Ground seems possible based on prior diagrams, but only you know what you've built.
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Old 23rd April 2012, 07:07 PM   #983
Zen Mod is offline Zen Mod  Serbia
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@Gerd

no

just one of pretty regular ZM's brainfarts

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Old 23rd April 2012, 08:10 PM   #984
generg is offline generg  Germany
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But you all can help me !!!!

I do not know what is the better possibility grounding at 0V or at the negative reference...
Attached Images
File Type: jpg SIT Mu passive biasing normal.JPG (63.8 KB, 446 views)
File Type: jpg SIT Mu passive biasing -ref.JPG (69.6 KB, 429 views)
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Old 23rd April 2012, 08:20 PM   #985
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The one on the left is easier to read, therefore harder to screw up when you build from it
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Old 23rd April 2012, 08:21 PM   #986
Zen Mod is offline Zen Mod  Serbia
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probably #2
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Old 23rd April 2012, 08:49 PM   #987
generg is offline generg  Germany
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O.k. I am never perfect, must be a disease....

I forgot in both pictures the 10k resistor going from the node point input cap and 47R gate stopper to the wiper of the 10k biasing pot of the SIT.

You can see this 10k resistor in all pictures of Mike!

And the connection from the 4k7 resistor to,the output node is not necessary.
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Old 23rd April 2012, 09:19 PM   #988
generg is offline generg  Germany
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@juanitox did you do your vote ......

I tried your suggestion with the self biasing and Hammond circuit.
I found it difficult in my system to hear a distinctive difference to the biasing with a separate PSU.
But the sound differences between the Hammond and thick film and CCS solutions are easy to hear even in my system.
But thank you for the suggestion to have more porn....
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Old 24th April 2012, 07:36 AM   #989
generg is offline generg  Germany
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the 3R5 biasing resistor delivers the biasing voltage that you can fine-tune with the 10k pot, I would keep the value of the 3R5 resistor as low as you can. It depends on the current you want to have for the 2SK82. With 2A and 3R5 you get a maximum bias voltage of 7V. That might be unnecessary high, so you can go with the resistor value a bit lower. With 1,5A you can calculate yourself....
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File Type: jpg SIT Mu passive biasing -ref.JPG (54.6 KB, 413 views)
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Old 24th April 2012, 01:06 PM   #990
protos is offline protos  Greece
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I still cannot understand the biasing network of this circuit. What is the voltage at -ref and where do you get it from?
From my point I see the vfet biased by a 3r5 to ground BUT then I see a -ref attached to the source. Since the current will flow in the path of least resistance it should flow from source to -ref and basically the source is at -ref voltage whatever resistor you may put between source and 0V.
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