# Polarity of input signal and capacitor in voltage clamper

I am stuck at understanding how voltages add up in a voltage clamper, reading through Learning About Electronics - Diode Clamper and All About Circuits - Voltage Clamper, and also YouTube a few tutorials. If I have a simple clamper circuit with an AC input signal series with a capacitor and parallel to a forward or reverse diode and a load, after the first positive part of the input cycle charging the capacitor, once the diode is forward biased, the polarity of the capacitor's voltage would always be opposite to the polarity of the AC input signal (hence, DC-AC instead of DC+AC). The clamper circuit should shift the output signal horizontally through time, instead of vertically on the voltage.

Take the image as an example of a positive clamp circuit:

1. After initial positive input signal, input polarity reverse and capacitor is charged in the negative direction, thus voltage negative to positive from left to right
2. Input signal goes positive again but capacitor is charged in the opposite polarity and would cancel out instead of adding up the voltage

Clearly I am mistaking somewhere in the voltage clamper and hope someone can clarify.