few questions about the cmos-adsr

[smallstone]

hey guys,

sorry but my english ist not so well because iam from Germany.

In the moment i build the 8038 oscillator from Thomas Henry, i want controll the pitch via a keyboard with controll voltage.
Tomorow came the next components (resistors, capacitors) for the 8038 VCO. Then i finish the VCO.

After that i want build the ADSR from Thomas Henry, but i dont understand wehre i must connect the "gate" and the "trigger" on my 8038 VCO or keyboard.

Could you help me please ?


Thanks for your help, i hope you understand me

[elmegil]

If I understand correctly what you want to do, you will need a VCA as well. The one in Analog Synth for the 21st Century is pretty straightforward; I've built it as written (VCA + VCF) and also as a dual VCA (duplicate the core circuit for both halves of the V2164 chip).

the "traditional" arrangement is

keyboard CV -> VCO V/Oct
VCO out -> VCA audio in
Keyboard gate + trigger -> ADSR gate + trigger in
ADSR out -> VCA control in
VCA out == your "notes" with the envelope specified by the ADSR.

I googled for images but found very little. If you get Analog Synth for the 21st Century from Lulu it has a diagram at the end which includes these parts and many others.

[smallstone]

Yes, you understand me correctly.

But i have one more questions.

Is "gate" = Control Voltage ?


Thanks for your patience !

[elmegil]

No, a keyboard (or a MIDI2CV interface) will generally create three signals

1) CV is a voltage corresponding to the pitch of the key.

2) Trigger is a pulse corresponding to the initial press of the key.

3) Gate is a signal that is high while the key is pressed and low when it is released.

Many ADSRs will recognize gate, or trigger, or both. The advantage of both is it lets you do things like legato playing where the gate stays high the whole time but the envelope re-triggers on each key press.