[sdiy] NIC-based wave folder/shaper

[Scott Bernardi]

The schematic is correct, but shouldn't the "output" be at the inverting input of
the opamp (i.e., the "right side" of the 47K)?
I ran a simulation; with the pot at 50% rotation, a +/-5v saw is turned into a
phase shifted traingle with a glitch  on the upslope. Picture is at
http://home.attbi.com/~sbernardi/elec/NIC_wavefolder.gif.  The top trace is the
"output" at the inverting terminal, the middle is the input saw, and the bottom
is the opamp output.

Ian Fritz wrote:

> At 11:03 AM 1/26/2003, Scott Gravenhorst wrote:
>
> >Is this correct?  I love simple things like this.
>
> Your schematic is correct.  Thanks for taking the trouble to do
> it!  Remember that you may need to add 20 pF or so around the upper 100k.
>
> >Should the 100K resistors be 1% ?
>
> No.
>
> >Also, is there anything to be gained by changing the ratio of the 2 100K
> >resistors to something other than 1 to 1?
>
> The analysis is just a bit more conplicated with different values and the
> response will be different.  If you want to make the triangle accurate
> there will have to be a trimmer somewhere, but I haven't gotten that far yet.
>
>    Ian