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

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kenpeter

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Joined 2007
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.
 
Wavebourn

Wavebourn

Member
Joined 2006
wavebourn.com
kenpeter said:

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?
Click to expand...


You can drive the whole MOSFET by an additional follower. :cool:

Tower-concept.gif
 
tiefbassuebertr

tiefbassuebertr

Member
Joined 2005
tiefbassuebertragung.de
concerning the 2SK77 I found this weblinks
http://www.diyaudio.com/forums/showthread.php?postid=1537367
http://www.diyaudio.com/forums/attachment.php?attachmentid=110125&d=1213295651
http://web.archive.org/web/20070322215124/http://www.maxonic-audio.com/sitpoweramp/
http://www.sibatech.co.jp/maxonic/amp.html
http://www.stereosound.co.jp/hivi/detail/newsheadline_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/roadtourdigitaldomain/visit.html
 
R

roerdomp

Member
Joined 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.
 
tvi

tvi

Member
Joined 2001
Digital-Do-Main go to the trouble getting the devices made for them, their patents mention a company called SYSTEC KK as co-applicant.
Could be: Systec Research, Inc

Some of their patents
Dual Static Indution Transisitor in Adjacent Arrangement Within Chip & Power Amplifier Circuit for Audio Using the Same

Push-Pull Using Static Indution Transisitor of the Same Conductive Type

Current Setting Circuit of Power Amplifier Circuit Using Static Indution Transisitor

And this might be of interest
High Speed, High Voltage, and Energy Efficient Static Induction Devices

Rgds
James
 
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tiefbassuebertr

tiefbassuebertr

Member
Joined 2005
tiefbassuebertragung.de
roerdomp said:
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.
Click to expand...

At my opinion it would be the best way to emulate the V-FETs with today's available parts.
Anywhere a discrete op amp was created with same PCP surface sizes than a normal integrated version (somewhere here on the forum has been explicite reported, but I don't know the exactly title of the subject)

Actually the same must be possible for the vintage V-FETs.

The PA02 e.g. from Apex Precision Power offers IC's in a TO-3 like outline:
http://www.cirrus.com/en/pubs/proDatasheet/PA02U_O.pdf
I read here, that this are no monolitic versions but thickfilm-technology, that is similar to SMD
PA02 pdf, PA02 description, PA02 datasheets, PA02 view ::: ALLDATASHEET :::
Some pics of this devices you will find by post #4 about
http://www.diyaudio.com/forums/soli...d-circuit-amplifier-overview.html#post2203515

If I order this Apex TO-Devices empty (i. e. without their thickfilm-PCB) and I have a circuit topology that create the right character so as appropriate power SMD FETs for solder on the TO3 die surface to get the typical V-FET Characteristic by higher realibility at the same time, then I have a good solution.
Ideal must be a jFET from Lovoltech together with cascode MOSFET/IGBT, but a commonly power MOSFET (even enhanced mode version) with Sziklai cascode consists of small signal 2SK170 jFET & BjT + BjT HV cascode transistor must us also bring to the wished targed function.

All the other possibilities have the disadvantage, that the Sony devices are hard to find and if I have success, I get still used devices.
 
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Nelson Pass

Nelson Pass

The one and only
Joined 2001
Paid Member
I have been playing with some of these parts. When you
talk about using or emulating them, the key question is "What
characteristic of the Vfets or SITs is of greatest interest to you?

For me, it is the characteristic of the output (Drain) conductance.

:cool:
 
tiefbassuebertr

tiefbassuebertr

Member
Joined 2005
tiefbassuebertragung.de
Nelson Pass said:
I have been playing with some of these parts. When you
talk about using or emulating them, the key question is "What
characteristic of the Vfets or SITs is of greatest interest to you?

For me, it is the characteristic of the output (Drain) conductance.

:cool:
Click to expand...


I would generally prefer that characteristic, that makes at one hand expect nearly the same distortion behavior, but at other hand the least possible change in the amplifier topology itself (concerning the model, which is to repair).
The fact, whether the threshold voltage (Vgs) is in the positive or - as in the original V-FET device - in the negative area is located, is less important.
Much more important is an quite identical curvature of all transfer characteristic curves itself - this is the main challange - so I think.
 
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tiefbassuebertr

tiefbassuebertr

Member
Joined 2005
tiefbassuebertragung.de
about
New SONY V-Fet reliability problem discovered ! - AudioKarma.org Home Audio Stereo Discussion Forums
I read by last post #19 from "Mr. V-FET" follow (written five years ago):
V-Fet emulation:
I worked on that for a while and I found that it is possible to
bring a 150W V-Fet emulating circuit (including a MOSFET as power device) completely into a TO-3 can.
But the end price for such a device would end up at perhaps 50$ per piece at 1000 pcs.
Who would be willing to pay such a price for a 150W transistor ?
 
tiefbassuebertr

tiefbassuebertr

Member
Joined 2005
tiefbassuebertragung.de
tiefbassuebertr said:
about
New SONY V-Fet reliability problem discovered ! - AudioKarma.org Home Audio Stereo Discussion Forums
I read by last post #19 from "Mr. V-FET" follow (written five years ago):
V-Fet emulation:
I worked on that for a while and I found that it is possible to
bring a 150W V-Fet emulating circuit (including a MOSFET as power device) completely into a TO-3 can.
But the end price for such a device would end up at perhaps 50$ per piece at 1000 pcs.
Who would be willing to pay such a price for a 150W transistor ?
Click to expand...
The diyaudio member Jon Lord tell me similar conditions concerning V-FET's from SONY and Yamaha, but however - he is also able to do this - go to #145 about
http://www.diyaudio.com/forums/solid-state/114865-densen-amp.html
to look his profile
 
tiefbassuebertr

tiefbassuebertr

Member
Joined 2005
tiefbassuebertragung.de
tiefbassuebertr said:
are there successors from currently production in the meantime?
Click to expand...
in this case this thread could be of interest:
http://www.diyaudio.com/forums/pass-labs/188066-first-taste-papas-new-devices.html

The brand "Power Integrations Inc" about
http://www.powerint.com/en/design-support/application-notes
is able to create intelligent MOSFET's like follow example for switching applications:
http://www.datasheetcatalog.org/datasheet/powerint/TOP202.pdf
This means for me, that this brand is probably also able to introduce intelligent V-FET's, suited as improved successors for all V-FET's from Sony, NEC and Yamaha, but with very enhanced reliability in all respects.
In opposite to the old ones there must be a "built in" protection.
The question is only, which quantities for order are at least necessary so as wich flate rate costs for the singular developement costs.
 
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tiefbassuebertr

tiefbassuebertr

Member
Joined 2005
tiefbassuebertragung.de
Shinja said:
Hitachi's HA-500f employed 2sj20/2sk70 too.
HA-500f is more rarer than sansui's one even in japan.
I have gotten and maintained it but sold at auction yet.

Hitachi discontinued V-FET soon because they invented famous MOS-FET 2SJ50 2SK135 series...
Click to expand...
mean you this amp from Lo-D ?? - go to follow URLs:
Lo-D HA-500F
http://audio-heritage.jp/LO-D/amp/ha-500f.html
http://www.niji.or.jp/home/k-nisi/ha-500f.html
http://www.hifidiy.net/index.php?action-viewthread-tid-337714
http://www.real-audio.ru/measurements/shop/s-amp.html
 
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