Beyond the J Fringe

[codyt]

Just want to make sure they’re organized ‘and accounted for’

 

[Zen Mod]

as James Brown used to say - "Gotch'ya!"

 

[Michael Rothacher]

What, me worry?

 

[Cambe]

Hey Papa don't take no mess
Papa don't take no mess
Papa is the man who can understand
How a man has to do whatever he can
Hit me!
Papa don't- Papa don't- Papa don't
Papa don't take no mess no.
Also -- JB

 

[Nelson Pass]

The good news is that between Linear Systems and purchases of some Toshibas the supply situation is improving.

If the lower Idss spec JFETS' operate so well under greater stress, does this mean the V grade JFET's might make a nice power amplifier without having to use one thousand in parallel?

Yes, Through delicate negotiations, both the store and I have scored some
more Toshiba parts, some GR, some BL.

 

[vdi_nenna]

I'm confused by this sentence. Does it mean the value can be 1k or 10k load and 600 or 10k input impedance?

The load resistor is 1 kohms (1 thousand ohms) or 10 kohms and the impedance of the signal source is 600 ohms or 10 kohms, and I swept the 1 Khz source signal from 1 to 10 volts.

 

[Nelson Pass]

The curves curves show.the two loads. As explained in the text the two source impedance values gave the same curves.

 

[Blues]

Being high input impedance buffers 10kohms source impedance is peanuts!

 

[marconi118]

Any reliable source for these GR grade 170 and 74? Except linear lsk

 

[elwood625]

I've read this article a number of times last night, and I noticed that in both applications, no changes were made to the circuit for the lower Idss JFET's. It looks like a straight substitution.
Is there a thermal issue driving the lower Idss parts at the same bias as the higher Idss parts? In other words, will a small heat sink be necessary when using the lower Idss parts as a substitution?

 

[Zen Mod]

they still have same dissipation rating, whatever Ids range is

 

[elwood625]

Then is the Idss range for the manufacturer where the sweet spot of noise and distortion? Not sure if I fully understand why they have such distinct ranges when there is and can be such overlap.

 

[Zen Mod]

they didn't made investigations, of type Pa just did

who could expect that?

 

[coolnose]

You ?

 

[Zen Mod]

nope

I'm under Papa's disgrace again, so clueless about his recent mischiefs

 

[pfdavid]

Once again must thank Nelson for sharing his knowledge with we.lucky.few. Very interesting investigation. Chapeau!

 

[Soundhappy]

Thank you Mr. Pass
for new highly interesting article

In 1983 Toshiba data book show all jfets grades: Y, GR, BL, V
I guess " Y " grade Idss= 1~3mA is rare....
this was used by Mr. Hiraga in original " Le Monstre " 8 watts amplifier

source : http://www.rsp-italy.it/Electronics...ents/Toshiba Small Signal Transistor 1983.pdf

 

[Soundhappy]

Yes, Through delicate negotiations, both the store and I have scored some
more Toshiba parts, some GR, some BL.

Fantastic Mr.Pass
Thanks for good news

 

[ffarges]

thanks @Botte and @Superhappy for the articles! Great reading for the week-end!

 

[L0rdGwyn]

Thanks for the measurements Nelson. I came across Borbely's article earlier this week and had mentioned it on another thread, what timing, just as you said this was my introduction. I was in search of a single-ended JFET buffer that could drive the input capacitance of the THF-51S. Good to know lower Idss parts are on the table.

I hope this isn't too off topic, but I wonder if you have any experience with Borbely's JFET spin on the White Cathode Follower. Output impedance of this buffer is quite low, 2.3ohm as measured by Borbely and 4ohm in my simulation, I am planning to breadboard it in a THF-51S design, something like the below. This is my first time designing with SIT, so I apologize if I have overlooked some error.