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Old 7th November 2013, 08:39 AM   #1211
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Thank you for good news Elvee. I'm working on another notionally "deluxe" version using regulated symmetrical powered DC coupled B1 buffer, CCS as R21, ~45V rails, 2SC2922's at output. Sims seem showing good results with adjusted compensation.
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Old 9th November 2013, 03:41 PM   #1212
Piersma is offline Piersma  Netherlands
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Default latest Circlophone incarnation

Inverted JFET Circlophone,

With reference to post number 331 of this threat, this is final version of the “inverted JFET Circlophone”.
Real life implementation of the attached schematic is shown in the picture.
The design is fully tested and approved by the designer of the original Circlophone, Elvee.

Highlights of this version:
Scalable outputpower, rails up to 50V
JFET input, (virtual) absence of gate/base modulation
Improved step response of the CFP configuration
Reduced phase splitter dissipation
Original Circlophone features:
No (very low…) cross-over distortion, semi class A
No need for thermal tracking the output devices
Idle current 200 mA, Gain : 28 dB
Attached Images
File Type: jpg Inverted JFET Circlophone.JPG (93.0 KB, 664 views)
File Type: jpg Inverted Circlophone PCB.jpg (247.9 KB, 634 views)
File Type: jpg Inv. Circlophone PCB.JPG (233.7 KB, 612 views)
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Old 9th November 2013, 04:13 PM   #1213
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Piersma, tell us how it sounds in comparison to the original.

Any chance of a PCB layout for thermal transfer? I understand it is double sided. Thanks.
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Old 10th November 2013, 09:44 AM   #1214
Piersma is offline Piersma  Netherlands
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Default Inverted Circlophone

Sam,

Soundwise i cannot detect any difference between the original Circlophone and the "inverted" version, but i have thin ears. Somewhere next week i will upload the board files, it's a dual layer board.
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Old 8th December 2013, 02:04 PM   #1215
Piersma is offline Piersma  Netherlands
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Default Board Files

Inverted Circlphone PCB files.

Note: Zobel (R=5E6, C=47nF) is optional !

have fun!

Last edited by Piersma; 8th December 2013 at 02:07 PM.
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Old 16th December 2013, 02:11 PM   #1216
jerryo is offline jerryo  Isle of Man
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Anyone fancy doing a "Circlophone" pcb with power supply section components on the same board, if possible?
Just a thought!
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Old 8th January 2014, 06:22 PM   #1217
Piersma is offline Piersma  Netherlands
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Default MOSFET OPS

This is the last and lastest version of the inverted JFET Circlophone with a MOSFET outputstage. This configuration is thoroughly tested and can also be used with the latest published PCB. Great performer!

have fun!
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File Type: jpg inverted Circlophone MOSFET OPS.JPG (84.3 KB, 299 views)
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Old 14th January 2014, 02:50 PM   #1218
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I'm working on another MOSFET version for a friend. It is based on HEXFET outputs and keantoken's buffered input stage arrangement. I made a simulation according to my devices on the shelf. Everything seem fine with the models that I found at various sources and customized compensation values. But I have no clue about amp's predicted stability margin. Any suggestion appreciated in this regard.

Thanks.
Attached Files
File Type: asc Circlophone-MOS-CCS-BUF.asc (10.4 KB, 16 views)
File Type: txt terra-models.txt (927 Bytes, 19 views)
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Old 14th January 2014, 03:25 PM   #1219
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I'm surprised anyone remembers that.

It looks like your FETs are running at 7.5A bias. You forgot R22 in the schematic above your post.

EDIT: Here, an attached schematic with R22 and the AC analysis fixed. A bit peaky. The compensation could stand some tuning for sure, but it doesn't seem to be blowing up yet.
Attached Files
File Type: asc Circlophone-MOS-CCS-BUF.asc (10.5 KB, 17 views)

Last edited by keantoken; 14th January 2014 at 03:29 PM.
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Old 14th January 2014, 04:54 PM   #1220
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Quote:
Originally Posted by keantoken View Post
I'm surprised anyone remembers that.

It looks like your FETs are running at 7.5A bias. You forgot R22 in the schematic above your post.

EDIT: Here, an attached schematic with R22 and the AC analysis fixed. A bit peaky. The compensation could stand some tuning for sure, but it doesn't seem to be blowing up yet.
Thanks for input. I thought that resistor (R14 in original schematic) is going to be superfluous if I use CCS in place of R21, as what I did in schematic.

I'm working on another possible compensation values now.

Last edited by terranigma; 14th January 2014 at 05:22 PM.
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