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What To Do With Those 2SJ28's
What To Do With Those 2SJ28's
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Old 26th April 2017, 03:33 PM   #31
Michael Rothacher is offline Michael Rothacher  United States
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What To Do With Those 2SJ28's
We've got some lovely ideas flowing, gentlemen
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Old 26th April 2017, 05:19 PM   #32
Circlomanen is offline Circlomanen  Sweden
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SLAPS-2sk28.jpg

4 parts and a power supply constitutes a feed forward error correcting (SUSY-ish) power amp with very low levels of distortion. 2 X voltage gain.
It has a very good damping factor, due to the feed forward EC and the NFB.

If the 2SJ28 needs a gate resistor then the amp needs 5 components per channel plus a power supply.

L1 and L2 are two windings (bifilar) on an aircored choke. Since they are very close magnetically coupled together they will force the two outputs to closely follow each other in anti-phase (hence the SUSY-"ish" feed forward error correction).

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Johannes
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Old 26th April 2017, 05:47 PM   #33
Circlomanen is offline Circlomanen  Sweden
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FFT-SLAPS-IRFP9240.jpg

I simulated this amp with an IRFP9240.
11.2 volts P-P output with 0.10% THD into a resistive 8 ohm load.
A nice balance of the harmonic content in the FFT graph.

All this is a simplified simulation, and should only be taken as a crude approximation of a real amp driving a real load.

Cheers,
Johannes
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Old 26th April 2017, 06:58 PM   #34
Soundhappy is offline Soundhappy  France
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Quote:
Originally Posted by Circlomanen View Post
I don´t have any spice model for the 2SJ28....
Uncle Mike SIT Modeler software get presented 2SK82 data.
Good start for creation of new 2SJ28 spice model by the experts
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Old 26th April 2017, 07:19 PM   #35
Michael Rothacher is offline Michael Rothacher  United States
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What To Do With Those 2SJ28's
We could approximate one by flipping a couple of the polarities in the behavioral model like so. Close enough for government work. Don't try to land a probe on Europa with it.

As presented, it's simply a mirror of the 2SK82, feel free to adjust to taste.

*--------------------------------------------------
*2SJ28
*GENERATED BY SIT MODELER @ AUDIOMAKER.TECH
*MODEL RANGE: -55V, -5A
*--------------------------------------------------
.SUBCKT 2SJ28 D G S ; Drain Gate Source
+ PARAMS: MU=7.3 X=1.51 K=0.157 N=2.24 VCT=0 RG=2MEG
*--------------------------------------------------
B1 D S I=-1*(K*PWR(URAMP((-V(G,S)+VCT)+(N*LN(-V(D,S))+(-V(D,S)/MU))),X))
*FOR LTSPICE
R1 G S {RG}
CGS G S 0P
CGD G D 0P
CDS G S 0P
.ENDS 2SJ28
*--------------------------------------------------

Plug in you favorite interelectrode capacitances if you're going to fool with bandwidth stuff.
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Old 26th April 2017, 07:45 PM   #36
Zen Mod is offline Zen Mod  Serbia
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What To Do With Those 2SJ28's
Quote:
Originally Posted by Michael Rothacher View Post
......., feel free to adjust to taste. ...........
yeah

especially Mighty Moi adjusting that

I'm not talented even for agricultural work around LTSpice models

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Old 26th April 2017, 09:22 PM   #37
Soundhappy is offline Soundhappy  France
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Quote:
Originally Posted by Michael Rothacher View Post
We've got some lovely ideas flowing, gentlemen
**********
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Old 26th April 2017, 09:42 PM   #38
Zen Mod is offline Zen Mod  Serbia
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What To Do With Those 2SJ28's
perfect

(I'm jealous that someone invented that before me )
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Old 26th April 2017, 11:13 PM   #39
res07njc is offline res07njc  United States
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Speaking of things already invented, perhaps someone will post a +/- PS amp that borrows Papa's TL431 reg from Sony Part2?
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Old 26th April 2017, 11:48 PM   #40
Soundhappy is offline Soundhappy  France
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Adapt elements from John Broskie Aikido mojo logic but for 2SJ28 stage with circuit who self-cancel his noise ?
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File Type: jpg 16948301-3D6B-4226-BB13-A75BB3CEE1DD.JPG (21.9 KB, 365 views)
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