Krazy JFET-cascoded Pass BOSOZ
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jh6you
Account Disabled

Join Date: Aug 2002
Location: Near to the Pacific Ocean
Krazy JFET-cascoded Pass SOBOZ

Hi

I am trying to build this.
My most concern is how to set up the gain of about 14-20dB.

Appreciate any comment, advice, or criticism . . . plz . . .

Regards
jh
Attached Images
 krazy jfet cascoded bosoz_rev0.jpg (28.6 KB, 1677 views)

 2nd February 2006, 09:44 AM #2 wuffwaff   diyAudio Member     Join Date: Aug 2001 Location: Ingolstadt Germany Hi, gain is set through the drain resistors and the chosen fets. gm = 2xIdss/Vp Gain = gm x Rdrain I donŽt have any data on the J310 so youŽll have to calculate it for yourself. What is the resistor between output and input? William __________________ een ooievaar is geen konijn want zijn oren zijn te klein!
jh6you
Account Disabled

Join Date: Aug 2002
Location: Near to the Pacific Ocean
Thanks, William

Well noted.
Attached is a brief data about J310 I prepared.
I am thinking the Rd of 1K.

The minimum Gfs of J310 is 0.008mhos.
Min. voltage gain A = Gfs x Rd = 0.008 x 1000 = 8 (18dB)
The maximum Gfs is 0.018mhos.
Max. A = 0.018 x 1000 = 18 (25dB)

Hmmm . . . the gain would be between 18-25dB.

The resistor betweem the output and the input is my "uncertainty." I was unsure about the voltage gain of this concept so that I put my "uncertainty" there in case I need a negative feedback. I will remove it and repost the circuit.

Any other comments . . . ?

Regards
jh
Attached Images
 j310 data.jpg (41.3 KB, 1181 views)

jh6you
Account Disabled

Join Date: Aug 2002
Location: Near to the Pacific Ocean
Attached is Rev.1

Help me with your comments . . . plz . . .

Regards
jh
Attached Images
 krazy jfet cascoded bosoz_rev1.jpg (26.6 KB, 1237 views)

jh6you
Account Disabled

Join Date: Aug 2002
Location: Near to the Pacific Ocean
And, re-estimated the voltage gain.

Min. A = 0.011 x 1000 = 11 (20dB)
Max. A = 0.013 x 1000 = 13 (22dB)

Hmm . . . 20-22dB . . .

I wonder if this way of estimation is correct.
So far, nobody seems intersted in or has no time . . .

Regards
jh
Attached Images
 j310_gfs.jpg (38.7 KB, 1024 views)

 3rd February 2006, 01:55 AM #6 Zen Mod   Official Court Jester diyAudio Member     Join Date: Jan 2003 Location: ancient Batsch , behind Iron Curtain I dunno.... now I'm breakin' and bangin' my head with Aleph J besides-I'm greenhorn.... __________________ my Papa is smarter than your Nelson ! clean thread; Cook Book;PSM LS Cook Book;Baby DiyA ;Mighty ZM's Bloggg;Papatreasure;Papa...© by Mighty ZM
 3rd February 2006, 02:13 AM #7 jh6you Account Disabled   Join Date: Aug 2002 Location: Near to the Pacific Ocean I see . . . Following this project, I go with JFET-cascoded F1 . . . Regards jh Where is my power JFET . . . Where are they . . .
Flemming J P
diyAudio Member

Join Date: Oct 2001
Location: Sweden
Quote:
 Originally posted by jh6you I see . . . Following this project, I go with JFET-cascoded F1 . . .

I was thinking about the same thing, but due my limited understanding of the world and more specificly mofsets/jfets I need a complete ciruit.

jh6you
Account Disabled

Join Date: Aug 2002
Location: Near to the Pacific Ocean

Hurry up . . . ?
The music from F1 is already !!!
I do not have the power JFET . . .
Mmm . . . I could create a new thread with a conceptual darwing . . . if the master does not mind . . .

I donnu MOSFET/JFET either, but we are lucky with good supports here . . .

Back to the subject, I am going to try the shown Krazy, 10 days later when I return back to the exciting hell from the boring heaven I am staying now. Still have time for your positive or negative feedbacks.

Regards
jh
Attached Images
 krazy jfet cascoded bosoz_rev2.jpg (31.1 KB, 1133 views)

 3rd February 2006, 08:36 AM #10 Flemming J P diyAudio Member   Join Date: Oct 2001 Location: Sweden Ok ok, I will build the F1. I am still waiting for my heatsinks for it, but I should get them soon. All the other parts are already waiting for me on my work table. I'm sure it will be much better than my gainclones, but I also know that I will have to change it to JFet F1 (or what ever it is goning to be called) when I can. If one only had the time to learn, but I have so many other projects and a full time job to care of. Good luck with the Krazy.

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