Re: TS808 schematic variants 08/ 09 /10 that part with C3 and R4 (pin 2 of OpAmp, 47nF and 4k7)

Posted by nocentelli on Nov 15, 2021; 6:47am
URL: http://guitar-fx-layouts.238.s1.nabble.com/TS808-schematic-variants-08-09-10-that-part-with-C3-and-R4-pin-2-of-OpAmp-47nF-and-4k7-tp50325p50326.html

j-pee wrote

at first I thought I spotted an error... now I know it can go any way...

but can it, really?

Yes. The order of components in series makes no difference to operation if there is only a single "input" and a single "output" to/from that particular branch. In this case, the input could be considered to be the opamp's inverting input, and ground/vref is the output: The order of the cap and resistor that join these two points is irrelevant.

On a second issue, actual ground (zero volts) and virtual ground (4.5v) also have no functional difference from the point of view of the opamp's inverting input IF A CAPACITOR IS USED, so that cap + resistor can be connected to ground (0 volts) OR to vref (4.5v) with no functional difference in the circuit's operation. You will occasionally see a circuit with the opamp inverting input connected to vref directly through a resistor with no cap present, but never directly to ground without a cap.