how to switch between normal signal and modified signal with analog intput signals arduino?

Question

I have a signal input like the sine V1 that is modified by the arduino and transformed it into a square signal. The value of the output depends on the value of a voltage reference given by a potentiometer. Both, the input signal and the reference are ADC inputs in the arduino. I put an interruptor just like the image, assuming PWM2 as arduino, and when the i put the interruptor in the position of the image i see the same voltage on the output as the potentiometer voltage reference, as is this where connected. Why is this happening ? can i do this in a different way ?

^{simulate this circuit – Schematic created using CircuitLab}

Answer 1

Are you looking for a bypass switch? This is very common in guitar circuits using a DPDT switch.

If you also want to switch power, you can use this method and use the other pole as a power switch, or you can just use the first method and a DP3T switch, which is a little harder to come by.

Picture credit http://screaminfx.com/tech/what-is-true-bypass-guitar-pedal.htm

Answer 2

You have the switch on the wrong side of the circuit. As shown you have the sinewave fighting the OUT of the Arduino. For example, if the Arduino output is low it will pull down the sinewave towards zero volts.

Move the switch to the other side and remove the short-circuit to ground.

^{simulate this circuit – Schematic created using CircuitLab}