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Old 29th July 2012, 08:21 PM   #6421
Salas is online now Salas  Greece
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(2.5/0.002) Vpp in your asc?
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Old 29th July 2012, 09:13 PM   #6422
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I have a question for the guys here.

I am trying to make the gainstage attached below working with the Servo.
Simulation shows that it works just fine, but when I try to implement it doesn't.
Any comment?


Thanks.
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File Type: png Gainstage+Servo.png (52.0 KB, 309 views)
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Old 29th July 2012, 09:17 PM   #6423
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Quote:
Originally Posted by Salas View Post
(2.5/0.002) Vpp in your asc?
yes, you are correct.
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Old 29th July 2012, 10:14 PM   #6424
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Stefano, here is a circuit that is similar to the JC Vendetta. Here the servo is connected to the source resistors of the input stage. You are not using a folded cascode so you have to use a non inverting servo in your case. The other option would be to make the second stage cascades floating and connect the servo there.
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File Type: pdf VENDETTA Servo example.pdf (69.2 KB, 94 views)
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Old 29th July 2012, 10:17 PM   #6425
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Thanks,

in the simulation it shows that if I make a non inverting servo it doesn't work! I wonder why!!

Oh gosh I didn't realize it was so similar to the vendetta!!! anyway thank you I will try it.
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Old 30th July 2012, 02:35 PM   #6426
hesener is offline hesener  Germany
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60 sets in the group buy, and counting......
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Old 30th July 2012, 05:08 PM   #6427
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That is quite amazing. Anyway, it is no mistake to build it. I am happy that after over 3 years in the making the wait is over.
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Old 30th July 2012, 05:51 PM   #6428
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That's pretty awesome!!!
Good job you guys and thank you for sharing such a woderful piece of work with us.
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Old 30th July 2012, 05:56 PM   #6429
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Joachim,

I am still working on simulation for servo gain stage and buffer.
Does the servo look good?
In this case it is not on the signal path, but I am not sure it could work in practive.
It simulates just fine and with an input offset it acts and zeros the output out.

Would you mind comment it?


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File Type: jpg gainstage+buffer+servo.JPG (114.9 KB, 235 views)
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Old 30th July 2012, 06:30 PM   #6430
MiiB is offline MiiB  Denmark
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Instead of the two resistors setting the current you could opt for a current source, this is a replicate of the household I did for the paradise... Now the servo works by injecting current into circuit to make the two halves amplify the same... This is for me an optimal way of implementing a servo, here it work just like an automated trimmer. Will it still work if you make R14/R30 larger....like 47 Kohms...??

I have tried to servo buffers...but somehow it's difficult, with one exception the single ended N-Jfet buffer, To me that is a beautiful design..

Last edited by MiiB; 30th July 2012 at 06:32 PM.
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