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Old 12th June 2007, 03:25 PM   #141
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Quote:
Originally posted by Babowana



If you adjust the value of R-Source, the bias current would be changed in amount accordingly. This would change the DC-voltage at the Drain, and might affect the target symmetrical amplitude of the AC-swing. If the AC-swing is symmetrical at the voltage gain you want to have, that would be the good result. Otherwise, we should recheck the values of R-Source, R-drain, other resistors, symmetrical swing and the voltage gain in total once again . . . and repeat the process till we get all of them.

If we should consider one more factor. It will be distortion.







(ya funny Serb with gigglewiggle eyes)
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Old 12th June 2007, 03:25 PM   #142
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Quote:
Originally posted by Manu


Thx for your hints. Should I let the drain res at 2K2 if I reduce the Source res to may be 6R?

If you adjust the value of R-Source, the bias current would be changed in amount accordingly. This would change the DC-voltage at the Drain, and might affect the target symmetrical amplitude of the AC-swing. If the AC-swing is symmetrical at the voltage gain you want to have, that would be the good result. Otherwise, we should recheck the values of R-Source, R-drain, other resistors, symmetrical swing and the voltage gain in total once again . . . and repeat the process till we get all of them.

If we should consider one more factor. It would be the distortion.


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Old 12th June 2007, 03:27 PM   #143
Zen Mod is offline Zen Mod  Serbia
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how's this...........

my quote of preceding post is suddenly before that preceding post?

ZM Blond
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Old 12th June 2007, 03:30 PM   #144
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Quote:
Originally posted by Zen Mod


how's this...........


Magic
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Old 12th June 2007, 04:07 PM   #145
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Quote:
Originally posted by Zen Mod





hehe

seems that hot weather is cause of confusion..........

anyway.......better than me- I'm confused all the time......

again........increase them,to increase local degeneration - feedback- so stage clipp later


(You may be right : with 6R I got only distortions, ahem)
I think I need a

Manu
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Old 12th June 2007, 05:02 PM   #146
Manu is offline Manu  Europe
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17 V PSU
15R Source Res
Same as before
I need some more

I'am too stupid for the Job, I'am afraid.
Manu.

Babowana : Thank for Your post.
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Old 12th June 2007, 05:38 PM   #147
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As Choky stated earlier:


Quote:
Originally posted by Zen Mod



when you use that sort of three legged fuses,you always must use pot on input,just because any not-attenuated signal will drive little bstrd in saturation and output sig will be more than clipped.
just look at bias voltage present between g-s and compare it with blabla 2V from CD out..........
Manu, I recall your using attenuation at the pre amp output -

Could this be the trouble? -or part of trouble....
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Old 12th June 2007, 06:15 PM   #148
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Quote:
Originally posted by mpmarino
As Choky stated earlier:

Manu, I recall your using attenuation at the pre amp output -

Could this be the trouble? -or part of trouble....

I will check that, but without pot at the output I get some very dangerous noises.

After changing all connectors, the things improves somewhat, but still much to much distorsions.

I will try with some better pots at the input.

Again , I'am too incompetent for the job, and I don't wan't to give the impression that there is something wrong with the JFET BOZ.



Manu
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Old 12th June 2007, 07:14 PM   #149
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So I think I give up for today. Have to cook something for my (beautiful) bosnian girl-friend.
Wok with broccoli and cashew nuts I think.
Zen Mod
Now you got me.

manu (too incometent to give up)
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Old 12th June 2007, 07:16 PM   #150
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Quote:
Originally posted by Manu



I will check that, but without pot at the output I get some very dangerous noises.

After changing all connectors, the things improves somewhat, but still much to much distorsions.

I will try with some better pots at the input.

Again , I'am too incompetent for the job, and I don't wan't to give the impression that there is something wrong with the JFET BOZ.



Manu
Manu dont despair, you are doing great.
Do you have a picture of the board with the resistor values you used on it? The layout seems correct, but it would be nice to see the values.
Another thing, did you try and measure the actual bias current to see if it is as its supposed to be? If not; then measure the voltage drop across the source resistor and divide the value you get with the source resistor value to get the bias current. I=V/R

Steen
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