SemiSouth boiler room

[Antoinel]

I recorded enough data points to see that I might have chosen a random sample that has a higher than the typical Vgs value from the data sheet. So, I find from the graph below that we do not see that triode-like curve, as I thought I was seeing yesterday. Hmmmm
Sorry about some of the details. X = Vds (V), Y = Ids (A).

flg, in post #47, Dr Mazzola has a way [in upcoming article] which enables a SemiSouth JFET to behave like a SIT. Zen Mod has promising results using Schade Feedback as he said in post #50. Dr. Mazzola may wish to early release a schematic of this hot topic.

 

[flg]

Some time ago, on a day I was snowed in, maybe you too? buzz and mike exchanged a little about operation with negative current. maybe that's what you want to figure out???
I'm still messin with normal operation.

 

[buzzforb]

btw.

anyone having SJEP170R550 LTSpice model ?

just having idea for small Ultrasymmetry gain stage

Bad ZM.

 

[Antoinel]

btw.

anyone having SJEP170R550 LTSpice model ?

just having idea for small Ultrasymmetry gain stage

Please show schematic of idea if you wish. Great food for thought.

 

[flg]

Hey ZM, maybe you could explain what's the difference between my "supersymetry" pre idea and "Ultrasymetry".
You better not tell me to go read the XS lit!
A picture is worth a thousand words
I can go home and find an X-600 pic that looks like my "Supersymetry"

 

[Zen Mod]

big mouth as I am , it's tempting ....... but no , no this time - I'll continue embarassing my self in public - with lesser things

if Pa didn't gave details in public - what's that Ultrasecret thing called Ultrasymmetry , I can't give my regular spiegazione de paesano

 

[buzzforb]

 

[Zen Mod]

there we go

next post is Jacco's , putting poor Orouboros in some sexual context

 

[buzzforb]

We cannot let him get into this. It will be no turning back.

 

[flg]

Hey ZM, maybe you could explain what's the difference between my "supersymetry" pre idea and "Ultrasymetry"...
A picture is worth a thousand words ...

They look the same don't they?
Ohh, Papa uses an extra pair of nasty gain devices???

 

[buzzforb]

Like I said. Tooo compllicated

 

[flg]

Back to our regularly scheduled pgm...
ZM Same as last time with the addition of a .25 ohm Rs, X= Vds, Y= Ids

 

[Zen Mod]

sorry - I disregarded fact that you're primary interested in low current & low voltage area ;

in that case - choose bigger , arbitrary for start , value for Rs

say 3R3 , then build from that

gain will suffer , but who cares

 

[flg]

Not bad there ZM I guess a little more Ids would be representative of our typical operating point.
Comparing my first graph to one with a source resistor (of ZM's Choice), we easily see the no Rsource configuration was begining to get much higher gain at higher current. The Vgs applied was nice even intervals of .1V. If the gain were stable or flat across the range I was testing, the the curves would also be at equal intervals. As can be seen in the graph with the Rs of .25

 

[Zen Mod]

those are olde triode tricks , from yore tricksters

 

[flg]

So ZM, you want to see up to 4 or 5A. I kinda like this Rs value. I'll start with that...

 

[Zen Mod]

nope - I'm just implying which value(s) for RS , to investigate low I/U region

I'm not wanting to see anything particularly

 

[flg]

If there ate no more requests I'm going to run it up towards 20Vds and a few amps Id.
Then I want to try the R085

 

[buzzforb]

Run away!

 

[Shiege]

I will attend PCIM-Europe this year (again) and listen (again) to Infineon announce this JFET. How many times now? These devices were developed by a small German company called SiCED that Siemens and Infineon invested in. They've been trying to find a market for these things for 10 years. I bought some when they were made by SiCED, which Infineon then acquired. I'm trying to find the parts lost in my lab somewhere to see if they might be good for audio. I remember they weren't much good for switching due to depletion mode with very negative pinch-off voltage. Infineon is trying to fix that by selling a dedicated gate driver chip and giving it a catchy name like "CoolSiC" to co-market with their "CoolMOS" brand super-junction silicon MOSFETs. For audio, it's all in the saturation characteristics. Depletion mode is like a tube, so many audio folks won't care. I don't think they will be cheap.

If you do not find them in you lab I could have a look in mine and borrow you some. I think I am to busy and not experienced enough for audio applications ;-)