[sdiy] Idea - Triangle wave DCO core

[ASSI]

On Wednesday 14 March 2012, 10:15:54, Tom Wiltshire wrote:
> It occurred to me today that you could fairly easily build a triangle core
> DCO. This wouldn't use a reset pulse, but would instead use a bipolar
> DAC.
> 
> You'd simply output a charging CV from a DAC to an integrator. After half
> a cycle has been timed by the uP, it switches the DAC charging CV to the
> opposite polarity. And so on. Instant triangle wave at known frequency.

Nope.  Don't use a voltage out DAC if you need a current out into the 
integrator.  And if you already get a current out DAC, chose one with an 
external reference that you can flip to both polarities based on a 
comparator signal so the triangle wave stays centered between the rails.  
You do want to modulate the frequency, don't you?  The upshot is that you 
don't really need a very fast DAC for this.  Getting sync on is just a tiny 
bit more work.


Regards,
Achim.
-- 
+<[Q+ Matrix-12 WAVE#46+305 Neuron microQkb Andromeda XTk Blofeld]>+

Wavetables for the Waldorf Blofeld:
http://Synth.Stromeko.net/Downloads.html#BlofeldUserWavetables