[sdiy] Op amp for saw core VCO

[rsdio at audiobanshee.com]

On Oct 26, 2014, at 12:56 PM, Oren Leavitt <obl64 at ix.netcom.com> wrote:
> On 10/26/2014 1:29 PM, Tim Ressel wrote:
>> So your standard sawtooth core VCO with the integrator and discharge FET. I am re-designing an existing product that uses a CA3130 as the integration amp and want to update it. What is a good modern amp for this application? Or if you prefer, what kind of amp is needed here? Precision? High speed? I have used an OP37 and an OPA602 with good results, but I am hoping for an inexpensive alternative.
> 
> High input impedance for sure, and a fast slew rate to keep the reset step sharp.
> I'm with Ian on the OPA134.

If you're using an external FET for discharge, then I think you don't need to pay for exceptionally fast slew rate.

Brian