Project #03 – Add some envelope


This project adds an envelope to the synth sound.

It makes the volume of the tones to gradually fade in and out.

Step 1.

Build the synth like you did in project #02.


Step 2.

Rewire the right control knob like the Picture and insert the capacitor.
Mind the polarity of the capacitor (White band down to the blue stripe)
Connect the Filter VC to the red stripe so that its fully open all the time.



Step 3.

Verify that all connections are like the picture.

Finally connect the battery to the power strips.
Mind the color for correct polarity.

It should now be quiet when you connect the battery.
And make a sound when you push the button.

Turn the left knob to change the pitch and the right knob to adjust the time for tone to fade in and out.

This is called an envelope and makes the sound behave like when you pluck a string, changing the volume in time.

The control knob changes both the fade in and fade out time.

To zero out the fade in time and make it sound like a piano or plucked string insert a diode like in this Picture.

The diode bypasses the knob value when you push the button and makes the capacitor charge instantly  regardless of the knob position.

If you flip the diode the other way around it removes the fade out time and the synth turns quiet when you release the button.

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.