AW: [sdiy] AD/DA schematics? quantizers,etc

[Matthias Herrmann]

> -----Ursprüngliche Nachricht-----
> Von: synth-diy-bounces at dropmix.xs4all.nl
> [mailto:synth-diy-bounces at dropmix.xs4all.nl]Im Auftrag von Dan Snazelle
> Gesendet: Donnerstag, 14. Mai 2009 19:49
> An: jerryge at cableone.net; sdiy
> Betreff: RE: [sdiy] AD/DA schematics? quantizers,etc
>
> actually i was hoping to get at least close to 1v/oct
>
> my issue at this point seems to be either that my clock is not
> correct for this application
> or that my references and or offsets are wrong
>
> i am comparing the output of my quantizer to the ray wilson mfos
> quantizer and while mine IS doing something to the cv, it is not
> getting the nice steps in between notes that you get with a slow
> sawtooth,etc
>
>
> 1.
> i am assuming that for cv I WANT to be running the clock at a
> HIGH rate (say 400khz)
> i am using a 555 clock off of +5 and 0. is this ok?


i am using a simple schnitt trigger clock running at approx. 30MHz


>
> 2.
> i wish i knew a bit more about where to start looking for the
> errors. my offset trim right now on my output stage is between
> +12 and grnd (maybe as fonik said this should be going to a
> negative and a positive?)
>
> 3.
> AND my output is going through a 1uf cap which i think removes offset?


the cap alone would propably not do. add a 100k to GND after the cap (i.e.
22uF, neg to output).


>
> or should that come BEFORE the output opamp??
>
> 4. one other very important thing...for quantizers should i ditch
> the cap i have on the input before the input opamp?
>
> anyway...back to the bench....i am very close i think
>
>