Successors for V-FET SONY-Yamaha-TOKIN 2SJ28, 2SJ18/2SK60, 2SJ26/2SK76 and 2SK180 - Page 3

tiefbassuebertr · 12th August 2009, 05:34 PM

Quote:

Originally posted by h_a
Where do you have this circlotron from?

from - Shinichi-Kamijo go to
http://www.ne.jp/asahi/evo/amp/CSPP/2SJ18.htm

kenpeter · 12th August 2009, 05:54 PM

I'm not entirely sure this is even possible, but I'll bounce it off
the wall and see what sticks anyhow...

What if you abuse a 4 terminal MOSFET with separate connection
for substrate? And wire that to a resistive divider spanning from
drain to source... Does this sufficiently fake the space charge
effect that defines Mu? Would such a divider need an emitter
follower to drive the capacitance of the subtrate/body?

I think this body "diode" is forward biased when pulled higher
than drain? There might need to be a negative DC offset? maybe
a battery or something...

Its essentially a big unused JFET gate (depletion mode?) on the
flip side of the channel....

We abuse the old O.H.Schade method of bending a Pentode set
of curves into a Triode. Faking the distributed control surface of
a Triode's space charge with an external feedback network.

See Figure #35 if you have his paper "Beam power tubes".

Once you have emulated a Triode, you have emulated a V-FET.

RocketScientist · 12th August 2009, 07:21 PM

For those interested, I have started a new thread to discuss the SiC JFETs mentioned above here:

SemiSouth Power SiC JFETs

Wavebourn · 12th August 2009, 07:30 PM

Quote:

Originally posted by kenpeter

What if you abuse a 4 terminal MOSFET with separate connection
for substrate? And wire that to a resistive divider spanning from
drain to source... Does this sufficiently fake the space charge
effect that defines Mu? Would such a divider need an emitter
follower to drive the capacitance of the subtrate/body?

You can drive the whole MOSFET by an additional follower.

kenpeter · 13th August 2009, 12:41 AM

Thats not quite what I meant (about driving the substrate)...

Wavebourn · 13th August 2009, 12:52 AM

Quote:

Originally posted by kenpeter
Thats not quite what I meant (about driving the substrate)...

I know. It would save a lot of power.

tiefbassuebertr · 27th August 2009, 08:06 PM

concerning the 2SK77 I found this weblinks
http://www.diyaudio.com/forums/showt...postid=1537367
http://www.diyaudio.com/forums/attac...5&d=1213295651
http://web.archive.org/web/200703222...m/sitpoweramp/
http://www.sibatech.co.jp/maxonic/amp.html
http://www.stereosound.co.jp/hivi/de...line_1228.html
http://www.digital-do-main.com/
http://www.g-mark.org/search/Detail?id=34801&lang=en
http://item.rakuten.co.jp/eiwa-up/b-1a/
http://www.6moons.com/audioreviews/r...ain/visit.html

Helmuth · 27th August 2009, 09:28 PM

I bought 4X 2sj18 and 4x 2sk60 on ebay NOS and it works great again.

V-fet Repair of a WEGA V4810 solid state heaven

roerdomp · 6th February 2010, 09:41 AM

The extremely rare 2sj28/2sk82 for the TA_N88b and the 2sj18/2sk60 are offered on ebay all the time. I own a ta-n7b working with the 2sj18/2sk60 ranking 52 and 53 and works perfectly. So are the even rarer sansui Ba-1000 NEC v-fets (2sj20/2sk70). My Sansui Ba-1000 has been slightly modified to work great with sony 2sj18/2sk60 v-fets.

tiefbassuebertr · 13th April 2010, 11:49 AM

are there successors from currently production in the meantime?

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12th August 2009, 05:54 PM	#22
kenpeter diyAudio Member Join Date: Nov 2007 Location: Dallas	I'm not entirely sure this is even possible, but I'll bounce it off the wall and see what sticks anyhow... What if you abuse a 4 terminal MOSFET with separate connection for substrate? And wire that to a resistive divider spanning from drain to source... Does this sufficiently fake the space charge effect that defines Mu? Would such a divider need an emitter follower to drive the capacitance of the subtrate/body? I think this body "diode" is forward biased when pulled higher than drain? There might need to be a negative DC offset? maybe a battery or something... Its essentially a big unused JFET gate (depletion mode?) on the flip side of the channel.... We abuse the old O.H.Schade method of bending a Pentode set of curves into a Triode. Faking the distributed control surface of a Triode's space charge with an external feedback network. See Figure #35 if you have his paper "Beam power tubes". Once you have emulated a Triode, you have emulated a V-FET.

12th August 2009, 07:21 PM	#23
RocketScientist diyAudio Member Join Date: Mar 2008 Location: Northwest	For those interested, I have started a new thread to discuss the SiC JFETs mentioned above here: SemiSouth Power SiC JFETs

13th August 2009, 12:41 AM	#25
kenpeter diyAudio Member Join Date: Nov 2007 Location: Dallas	Thats not quite what I meant (about driving the substrate)...

27th August 2009, 08:06 PM	#27
tiefbassuebertr diyAudio Member Join Date: Jul 2005 Location: D-55629 Schwarzerden	concerning the 2SK77 I found this weblinks http://www.diyaudio.com/forums/showt...postid=1537367 http://www.diyaudio.com/forums/attac...5&d=1213295651 http://web.archive.org/web/200703222...m/sitpoweramp/ http://www.sibatech.co.jp/maxonic/amp.html http://www.stereosound.co.jp/hivi/de...line_1228.html http://www.digital-do-main.com/ http://www.g-mark.org/search/Detail?id=34801&lang=en http://item.rakuten.co.jp/eiwa-up/b-1a/ http://www.6moons.com/audioreviews/r...ain/visit.html

27th August 2009, 09:28 PM	#28
Helmuth diyAudio Member Join Date: Oct 2008 Location: Winterswijk	I bought 4X 2sj18 and 4x 2sk60 on ebay NOS and it works great again. V-fet Repair of a WEGA V4810 solid state heaven

6th February 2010, 09:41 AM	#29
roerdomp diyAudio Member Join Date: Feb 2010	The extremely rare 2sj28/2sk82 for the TA_N88b and the 2sj18/2sk60 are offered on ebay all the time. I own a ta-n7b working with the 2sj18/2sk60 ranking 52 and 53 and works perfectly. So are the even rarer sansui Ba-1000 NEC v-fets (2sj20/2sk70). My Sansui Ba-1000 has been slightly modified to work great with sony 2sj18/2sk60 v-fets.

13th April 2010, 11:49 AM	#30
tiefbassuebertr diyAudio Member Join Date: Jul 2005 Location: D-55629 Schwarzerden	are there successors from currently production in the meantime?