What To Do With Those 2SJ28's

[BeardyWan]

Possible, yes. Do you mean the 2SK182 / THF-51s?

yes both...
thanks

 

[Zen Mod]

.......

Other than matching gate voltage in order to self-bias, ......

there are voltages shown in Papa's Sony amps , so you can see what range of Ugs voltages you need for mating part

besides that , you also need to take in account higher rail voltages for FE , which is only way of achieving full swing of outputs , simply because swing of gates must be greater than what you need from power envelope

however , it's nice hoping , but for DEF amp you either need enormous stash of parts , plus enormous time to match them ....... or eeeeenormous luck to catch them simply buying few of each

in whichever way you succeed , don't forget to buy lottery ticket , you'll win 158% , being so lucky

 

[WBS]

Thanks for explaining ZM. That would explain the lack of news of anyone's success.

 

[Nelson Pass]

Does Mr. Pass play with NEC 2SJ20 triode ?

Got curves?

Are they available?

How many are you going to send me?

 

[Nelson Pass]

Has anyone found an N ch device that plays nicely with the 2SJ28 for use in a DEF amp design?

Other than matching gate voltage in order to self-bias, what would the needed parameters be? Is finding a suitable candidate simply a case of combing thousands of data sheets to find one?

Unfortunately the ones I have have Vgs starting at -8 volts or so and
go up into 11v, so it's tough to find a match. You would have to consider
a bias circuit.

There is another unrevealed trick in the SIT-3, but I haven't tried it with
such an extreme Vgs difference.

 

[WBS]

Aha! It's the unrevealed trick that's confounded me! I thought copying your simplified SIT 3 schematic might get me somewhere.

Silly me!

 

[Nelson Pass]

There is the Sony Vfet diy circuit coming that will allow you to do something similar
with a different approach.

 

[nicoch58]

hopes that ZM put a spycam in Papa ranch eheh

 

[Soundhappy]

Got curves?

Are they available?

How many are you going to send me?

Curves of the N channel part 2SK70 and some LTSpice models link
オーディオ自作賛歌 : SIT　NEC製　２SK70/2SJ20の特性とＳＰＩＣＥモデル

Yes NEC 2SJ20 are still available from Hong Kong Jim's Audio boutique, he get 100 % positive reputation
2SJ20 NEC V-FET Sit utilise une seule piece extremly rare!!! | eBay

How many ? No NEC's in my drawers but few matched pairs of different type exotica triodes can be send.
This transistor was not show by Mr. Pass on the bench interview with Steve Gutenberg..
shipping to US be possible next week.. Kind regards

 

[Zen Mod]

@nicoch58

nope

I tried acting as fly on the wall , but I was spotted from first moment

in fact , I was so efficiently controlled that I even didn't think of asking about secret projects

 

[nicoch58]

ZM Dazzling diamonds has blinded you forever

 

[Zen Mod]

naah

I'm blind from my tender teen age

which means , same as Obelix, I fell in that Kettle long ago

 

[nicoch58]

 

[Soundhappy]

I have a few of those NEC vfets (Ns and Ps) all tested good.
There is a chart somewhere in diy audio forums which shows their operating characteristics are very close to Sony versions..

In 1979 Mr. Jean Hiraga published article with amplifier schematic for NEC V-fets.

 

[indra1]

In 1979 Mr. Jean Hiraga published article with amplifier schematic for NEC V-fets.

Christophe, that one is a ticking bomb.

... Jean Hiraga fell into this trap in his conceptual drawing of the 30W class a with 2SJ20/2SK70 VFETs, and in fact introduced another problem in form of potentially fatal cross-conduction when clipping because of simply shoeing in VFETs where BJTs used to be....

 

[Soundhappy]

Thanks Indra for warning.
Year 1979.. 40 years in the past.... gets datasheet papers on the bench about this new NEC depletion transistors was much more complicated
than today with the computer or smarthphone on the WW web.
Despite rare VFet et SIT articles most of electronicians was not aware about triode semiconductors special needs.
Papa explore, educate Us about square law class A enveloppe without source resistors, DEFISIT etc.
After test's We can DIY amplifiers in security conditions now

 

[vdi_nenna]

Soundhappy, you know about this page, correct?

AMPLIMOS one stage amplifiers, amplificatori audio monostadio

 

[Soundhappy]

Correct Vince and SIT file

 

[Soundhappy]

News AudioMaker | DIY Audio Projects & More

 

[Nelson Pass]

We are looking forward to the happy day when Mike gets passed
his current obligations....

AND GETS BACK TO WORK ON DIY STUFF!!