SV: RE: [sdiy] Gate from pitch change

[Karl Ekdahl]

I think i managed to fix it (it's amazing what a good
nights sleep can do!), both sound and cv is
uC-generated but the cv apparently allways decays a
little in the beginning. So i made a op.amp.
comparator with a very sensitive threshold that
generates the Gate signal. Seems to be working! I'm so
happy i didn't have to get into the keyboard matrix
and solder 20+ cables to check for keydowns....

Karl

--- Fredrik Carlqvist <Fredrik.Carlqvist at iar.se>
skrev:

> 
> 
> Have you tried a pull-down resistor load on the VCA
> CV output? Maybe
> it's an open collector output or something like
> that. Seems strange to
> provide a CV out that cannot be used for anything
> interesting?
> 
> 
> Fredrik C
>  
> 
> -----Original Message-----
> From: owner-synth-diy at dropmix.xs4all.nl
> [mailto:owner-synth-diy at dropmix.xs4all.nl] On Behalf
> Of Karl Ekdahl
> Sent: den 3 maj 2006 05:15
> To: synth-diy at dropmix.xs4all.nl
> Subject: [sdiy] Gate from pitch change
> 
> Hi list, i'm hacking up an old Casio and need to get
> a gate signal to
> control an ADSR. 
> 
> The keyboard has both VCA CV output (and obviously a
> VCA!) and a squarewave output, both which decays a
> couple of 100 ms
> after key release which makes them unusable as
> direct ADSR gate. The
> only feasible way that i can think of to get a
> working gate out of this
> would be to detect pitch changes but i'm not sure on
> how to implement
> this. 
> 
> I'm thinking of a Voltage to frequency converter
> (LPF?) a S&H and a comparator but that seems
> unnecessarily complicated. 
> 
> Either way a pitch-change detector would only
> generate a new gate signal
> if a new key is pressed but i guess i'll have to
> live with that.
> 
> Any ideas would be appreciated!
> 
> Karl
> 
> 
> 
>