ODP: New Stuff

[Roman Sowa]

	>Finally, what do you think about differential pair with fully
balaned dynamic
	>load by a current mirror ? Like the one proposed by Roman at
> http://www.multimania.com/romcio/m_modvca.gif
	>I must admit I love the simplicity of his ciruit.

[RS]
I choose it because I wanted to have current output at 0V. This VCA goes
directly to next opamp summing node.


BTW - I have slight questions about the biasing of Roman's circuit,
especially
about the dc voltage levels around T2. Does it really work with the bases of
T2
and T3 at approximately the same level ? Roman ?

JH.

[RS]
It is close. Base of bias transistor sometimes gets "higher" than base of
signal
transistor, but it works! Those voltages are really small, in range of
30mVpp.
However, it introduces asymetrical distortion when voltage at T3 base
exceedes 30mVpp, and still I think it is because of differential pair in
itself
than T2 base at 0V. 
I will spend more time with this VCA soon, as I plan to make pan/x-fade/2vca
module using those circuits (already have the PCBs)

Roman

PS, today is 9.9.1999 isn't that cool? But I missed the time 9:09 this
morning :-(