[sdiy] Op amp for saw core VCO

[gordonjcp at gjcp.net]

On Sun, Oct 26, 2014 at 06:29:35PM +0000, Tim Ressel wrote:
> Hey,
> 
> 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.

One of the neat things about opamps is that they are all approximately interchangeable, within the limits of their spec.  So you can build your saw core VCO with whatever FET-input opamp you have lying around (like one of the couple of thousand TL07x opamps you have always got in stock because they're in everything) and later on swap it for a high-performance one if you feel it'll improve things.

-- 
Gordonjcp MM0YEQ