Negative peak clipping

Why you need the DC power supply?

Loss less zener diode is created such way. It can be somehow think as DC current reactance cuz power isn't dissipated when charges forced to move against voltage but absrbed and stored. Somewhat real life example of such lossless DC impedance is nothing more than discharged lead acid battery lol ...as long as it store power no heat is generated but 12 counter voltage is constantly established and attenuate source in the same means as zener diode but without heat (if it has low internal resistance) as the capacity start to fill up a heat will constantly builds up and bubles of hydrogen oxygen as chemical reactance is changing to active resistance partly a thermal partly a electrolysis