Answer 3—This circuit is called a voltage tripler. D1 is a half-wave rectifier that charges C1 to approximately 14 V, which is +V_A. On the half cycles where X is negative relative to Y (–14-V peak), D2 charges C2 to 28 V, or double the nominal value. Then, on the positive half cycles, the voltage on C2 is transferred through D3 to C3. +V_B becomes the sum of this voltage and +V_A, or approximately 42 V, which is triple the nominal value.

Contributor: David Tweed