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 17th June 2012, 02:48 PM #531 AndrewT   R.I.P.   Join Date: Jul 2004 Location: Scottish Borders I did a check on the numbers being presented in the plot. @ Vin=0.5V Vout=6V V*I=10W IR7*2=1.8A, IR7 = 900mA IR8*2=0.3A, IR7 = 150mA Id1*4=0.16A, ID4 = 40mA Id2=N/A From these I can calculate that Iout = IR7*2 + Id1*4 - IR8*2 = 1.66A Gain = Vout / Vin = 12 (this seems very high !) Peak instantaneous Power = 6V * 1.66A = 10Wpk Vrs = 450mV ID4 = 40mA @ 450mVf These (except for gain) seem to make much sense. They indicate that when at quiescent bias, the diodes are effectively OFF. When the output current has risen to twice the bias current, i.e. maximum ClassA output current of 1Apk, the diodes have a fairly low current contribution. When the amplifier has transitioned into ClassAB operation the diodes begin to make a significant output current contribution. Other than the odd gain, this is the information I have been looking for. Can we compare a high Vrs quiescent setting and how the diode current contribute to the output current for this? I'll be rash and make a prediction. If Ibias requires a voltage across the diodes that turns the Diodes ON, then we will see that "kink" in the plots. Can we do a differentiation of the current slope to show up the kink more easily? __________________ regards Andrew T. Last edited by AndrewT; 17th June 2012 at 02:53 PM.
Woody1911a1
diyAudio Member

Join Date: Nov 2010
Quote:
 Originally Posted by AndrewT How do I reset to my normal view of windows?

ctrl + scroll back to whatever size you like

 17th June 2012, 02:53 PM #533 palmito   :) diyAudio Member     Join Date: Dec 2010 Location: Florida,US On most modern web browsers, zooming the page in/out is standardized to holding the control key and using the plus (+) and minus (-) keys to zoom in/out respectively. Holding the control key down and pressing zero (0) resets the window to its original size. I'm not a mac person, so on the mac it may be the funky option key instead of the control key. However, with most images on web pages, which are of a fixed size, If they are already displayed with a one to one image pixel to screen pixel resolution, zooming will just "replicate" pixels and will make the image fuzzy. The more you zoom, the fuzzier it will get.
 17th June 2012, 03:06 PM #534 buzzforb   diyAudio Member     Join Date: Oct 2010 Location: Burlington, NC Question. What would happen if you removed the resistors? second question. How is the use of diodes different then putting a cap across the Rs? __________________ ...Shape the sound , Man! Last edited by buzzforb; 17th June 2012 at 03:22 PM.
lhquam
diyAudio Member

Join Date: Mar 2010
Location: Olalla, Oregon: Land of the 100 Valleys
Quote:
 Originally Posted by AndrewT I did a check on the numbers being presented in the plot. @ Vin=0.5V Vout=6V V*I=10W IR7*2=1.8A, IR7 = 900mA IR8*2=0.3A, IR7 = 150mA Id1*4=0.16A, ID4 = 40mA Id2=N/A From these I can calculate that Iout = IR7*2 + Id1*4 - IR8*2 = 1.66A Gain = Vout / Vin = 12 (this seems very high !) Peak instantaneous Power = 6V * 1.66A = 10Wpk Vrs = 450mV ID4 = 40mA @ 450mVf These (except for gain) seem to make much sense. They indicate that when at quiescent bias, the diodes are effectively OFF. When the output current has risen to twice the bias current, i.e. maximum ClassA output current of 1Apk, the diodes have a fairly low current contribution. When the amplifier has transitioned into ClassAB operation the diodes begin to make a significant output current contribution. Other than the odd gain, this is the information I have been looking for. Can we compare a high Vrs quiescent setting and how the diode current contribute to the output current for this? I'll be rash and make a prediction. If Ibias requires a voltage across the diodes that turns the Diodes ON, then we will see that "kink" in the plots. Can we do a differentiation of the current slope to show up the kink more easily?
The gain is correct. Look at Nelson's F5 Turbo V2 schematic. The feedback network has 2 x 220 ohm resistors in parallel (110 ohms) and 10 ohms to ground. That is a 12:1 divider.

I will work up a different presentation show output stage open-loop transconductance vs output current.

AndrewT
R.I.P.

Join Date: Jul 2004
Location: Scottish Borders
Quote:
 Originally Posted by Woody1911a1 ctrl + scroll back to whatever size you like
does not reset. Yes one can guess at what one thinks is about right.

Quote:
 Originally Posted by palmito ........Holding the control key down and pressing zero (0) resets the window to its original size............
this resets, whether I use the number pad or the numbers above the alpha pad.

Thanks.
__________________
regards Andrew T.

lhquam
diyAudio Member

Join Date: Mar 2010
Location: Olalla, Oregon: Land of the 100 Valleys
Here is another plot. It shows the transconductance of the upper MOSFET stage and currents through the source resistors and diodes versus the input voltage.
Attached Images
 turbo-gm-sim4.gif (13.9 KB, 453 views)

 17th June 2012, 03:51 PM #538 jacco vermeulen   diyAudio Member     Join Date: Oct 2004 Location: At the sea front, Rotterdam or Curaçao The I(D)-I(R7) envelope looks good.
 17th June 2012, 03:55 PM #539 Zen Mod   Official Court Jester diyAudio Member     Join Date: Jan 2003 Location: ancient Batsch , behind Iron Curtain KLUNK!-!KNULK __________________ 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
 17th June 2012, 04:21 PM #540 buzzforb   diyAudio Member     Join Date: Oct 2010 Location: Burlington, NC IlQuam, Have you run this same simulation at higher bias through Rs? __________________ ...Shape the sound , Man!

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