From Paul Schreiber
Sent Wed, Sep 10th 2008, 05:59
I am designing 2 new Frac VCO modules (1 analog, 1 digital) and I started looking at other folk's specs. Noticed that no one publishes (that I can find) what the scaling of the Linear FM input is. 500Hz/volt? 1000Hz/volt? Anyone have any ideas what would be a good spec? Second question: what would be an upper limit of +15V (-15V is pretty small) DC current spec? Is 100ma "a whole lot" or no big deal? The digital VCO uses 3.3V internally for the DSP (I have a little switcher for it). I am also looking at "high end" TI/Burr-Brown op amps that are supposed to be great sonically but suck current like no tomorrow. I'm going to have several people listen to different op amps to see if in this VCO instance, there is enough audible difference to justify adding 20ma current drain to the +15V line. For example, the Blacet Hex Zone is a 150ma module, and their 2100 VCO page lists nothing, "spec-wise" for power or the linear FM scaling. Maybe someone can measure it? Paul S.