Schematics / VCA 1 Linear-exponential
VCA1 linear/exponential by Scott Bernardi shared on his page as part of the lock box synth http://www.bernacomp.com/elec/lockbox/lockbox_home.html ,from the notes :
VCA1 has both linear and exponential inputs. The linear CV input is hardwired to the ADSR1 output. The exponential CV input is hard wired to the MIDI Velocity control voltage. This is how touch sensitivity is produced.
Read more on the theory of operation of both VCA's in the LockBox Synth here : http://www.bernacomp.com/elec/lockbox/lockbox_vca_oper.html