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Old 3rd January 2013, 01:29 PM   #11
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Quote:
Originally Posted by Mike H View Post
Before getting too involved with PCB design etc., have you made a lash-up prototype of this to make sure it all works as expected? I only mention it because spice simulations normally assume that all transistors are perfectly matched clones of one another and are closely thermally linked. In fact that all components are 'perfect'. Unless you deliberately put in variations that are more like real world scenarios. (?)

Just a thought....
I have to mount it on a breadboard of course. Obviously I DON'T assume transistor as be perfect! ;-). Some variations during simulations however has been done just for wiping out some bad surprises (that I've presented is, for now, the fifth arrangement of a more sketchy circuit).

Thanks for the thought! I appreciate it! :-)

Piercarlo
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Old 3rd January 2013, 01:35 PM   #12
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Originally Posted by tiefbassuebertr View Post
This topology could be a good upgrade (front-end) for Andrea Cioffoli's Power Follower 99
May be, but I've conceived it as a replacement of an ordinary SIGNAL voltage follower that must be inserted between switching input network and volume potentiometer.

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Old 3rd January 2013, 02:02 PM   #13
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Who's care of these "questions"? If I wish i can replace all just with a single op-amp connected as voltage follower... If I don't try so is because i wan't try something of different. I CAN do it and I DO it! :-)

Piercarlo
Many, much more than you think, just judge by the amount of members that are actually getting involved in the thread. What does the circuit bring thats new or does better or worse than others ??
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Old 3rd January 2013, 02:13 PM   #14
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Originally Posted by payloadde View Post
Your circuit looks similar to Maxim's BB3553 or LH0063 (used to be Burr Brown before).
http://www.datasheetcatalog.org/data.../493512_DS.pdf
These are not monolithic IC but thickfilm hybrid inside.
Ok, this is what I want to know. Too beautiful believe my circuit as a really new one! :-). The inner schematic of BB3553-LH0063 is conceptually similar to those from I started a couple of week ago. There are however a couple of improvements...

Homemodder, see you where are these improvements and what are the improvements obtained? ;-) Not the distortion, not the bandwidth, non only the SVR... (why?) ;-)

Piercarlo
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Old 3rd January 2013, 03:46 PM   #15
Mike H is offline Mike H  United Kingdom
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Originally Posted by Piercarlo View Post
Thanks for the thought! I appreciate it! :-)

Piercarlo
Cool, I was just checking
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Old 3rd January 2013, 03:48 PM   #16
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Originally Posted by Piercarlo View Post
What are the improvements obtained? ;-) Not the distortion, not the bandwidth, non only the SVR... (why?) ;-)
The major real improvement is input acceptance, which is limited only by voltage supply. Once provided that Q2 and the bipolars used in current generators - QGN2, 3, 4 - have enough VCE, the Vs may any you need for your required signal acceptance, even 300 volt if you will... Of course you have to choose even the right working voltage of capacitors but this is obvious. The JFET may be any with IDSS in the range of 2-3 mA. Intrinsic output impedance (before output capacitor) should be below 10 ohm.

The improvement of SVR (and linearity) is simply a biproduct of that featured above.

Piercarlo

Last edited by Piercarlo; 3rd January 2013 at 03:50 PM.
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Old 3rd January 2013, 04:53 PM   #17
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Originally Posted by Mike H View Post
Cool, I was just checking
This evening I'll look at the feature of "DropBox" for sharing files with everyone and I'll upload my schematic in LTSPICE. There is nothing here of "copyrights", "patents" and similar nuisances and the circuit can be studied - or improved: i'm not jealous!| :-) - by anyone want to do it.

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Old 3rd January 2013, 08:39 PM   #18
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https://www.dropbox.com/s/h09yspp5i6...P-Buffe-V2.asc

Please let me know if link work fine or not.

Thanks
Piercarlo
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Old 14th January 2013, 04:57 PM   #19
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Hi!

Circuit revision due to a serious design fault - a spurius SCR between a couple of transistor non revealed during simulation but (of course) readily "revealed" during breadbord testing. Here below the new schematic:

Click the image to open in full size.

The new file for simulation on LTSPICE is downloadable at the link below.

https://www.dropbox.com/s/14iyee1jzm...ffe-Revis3.asc

The new circuit is physically again under construction.

Piercarlo
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Old 15th January 2013, 05:08 PM   #20
Mike H is offline Mike H  United Kingdom
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Yep sounds familiar ....
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