MODULATE THE PITCH
This project makes the pitch follow the envelope..
It makes the volume of the tones to gradually fade in and out.
At the same time the pitch rises and falls with the volume.
Build the synth like you did in project #03.
Move the wire from the Pitch Control knob to the AMP VC.
Verify that all connections are like the picture.
Finally connect the battery to the power strips.
Mind the color for correct polarity.
The envelope circuit makes a control voltage that changes in time depending on the position of the knob and how long you keep the button pressed.
And the pitch now follows the envelope.
Like a siren or dropping a bomb.