JG´s Nobrainer and Nobrainer Discrete

[FdW]

Keep registering lower current in the lower half... is it normal ?

Plot I(R17)-I(R16) and all will be revealed also DO NOT USE THAT HIGH A BIAS (it's not improving anything (except global warming )). What you see is the non linearity of the OPS (output stage) due to class A operation (but not in a positive way) the + side compensates for the - side (so to say) and the other way around. The sum (or difference) of the currents shows the signal (not each of the currents).

 

[FdW]

I must say there are some compromises here..... difficult to use use another psu... can I keep the lovely 103 +-35v psu ?

Can I use other trannies (other than BC546/556) ?

2sa970/2sc2240 for instance

 

[FdW]

2sa970/2sc2240 for instance

Like here.

 

[FdW]

Change Q6 and Q12 also (Vce is borderline)

 

[brianco]

Hey Golden Titian Top, whats with .ASC files???

You trying to keep us elderly lightweight Mac guys out of it???

 

[RCruz]

2sa970/2sc2240 for instance

Change Q6 and Q12 also (Vce is borderline)

Can I use 2sa970/2sc2240 for Q6 Q12 ?

Where can I find the Toshibas ?

 

[FdW]

Can I use 2sa970/2sc2240 for Q6 Q12 ?

Where can I find the Toshibas ?

Yes you can!

In my transistor box [I did get a few 100 of each from eBay]

 

[FdW]

Hey Golden Titian Top, whats with .ASC files???

You trying to keep us elderly lightweight Mac guys out of it???

And for those who can't

You could install Wine http://wiki.winehq.org/MacOSX]
Or use parallels ]Run Windows on Mac - Windows and Mac side-by-side with Parallels Desktop 9 for Mac - Parallels
Or just miss the fun
Or get a real PC

 

[Joachim Gerhard]

So when the bias resistor is 165 Ohm R1, R2 are 115 Ohm ?
I do not see any Miller cap in this design.
Is the circuit stable without it ?

 

[brianco]

Thanks for the attachment FdW.

I won't have any Windows stuff here … being Irish anything like that is just too complicated.and when I did have a PC it was always a system problem which caused havoc!

 

[FdW]

So when the bias resistor is 165 Ohm R1, R2 are 115 Ohm ?
I do not see any Miller cap in this design.
Is the circuit stable without it ?

i did not yet test for stability, has to be done yet.

 

[FdW]

So when the bias resistor is 165 Ohm R1, R2 are 115 Ohm ?
I do not see any Miller cap in this design.
Is the circuit stable without it ?

R1/2 need more work.

 

[Joachim Gerhard]

Sure. I arived at 115 Ohm because that gave the best thermal stabily.
I used an amplified diode though in my prototype and not the transdiode string.
The transdiode idea came later but was never build, only simulated.

 

[RCruz]

Well, the transdiode thing works (very well indeed).... will now wait for r1/2 and thermal tests on the improved FdW version

 

[FdW]

Stability plot, the amp needs a 10p capacitor for compensation. The OpAmp has been changed to a LME49710

 

[Joachim Gerhard]

Many thanks.
What is the frequency response ( -3dB ) with this setup.

 

[RCruz]

I am using the 49710 opamp... but with 100p miller cap.... this is a good sign.....

Now, why do you use three transdiodes and not only two and increase the bias resistor a little bit ?


And here is something special indeed: Krylov - Bach - Toccata and Fugue - YouTube

This guy (Sergej Krilov) might as well be the highest violin player alive

 

[FdW]

I am using the 49710 opamp... but with 100p miller cap.... this is a good sign.....

Now, why do you use three transdiodes and not only two and increase the bias resistor a little bit ?

actually 10p (not 100p)

Still working on that, bias generators are a PITA (and the 3-trans-diode version works not bad)

 

[FdW]

Many thanks.
What is the frequency response ( -3dB ) with this setup.

Soon ... I need a bit of time

 

[Joachim Gerhard]

Sure, just curious.