AC voltmeter circuit composed of milliammeter a

By adding a few semiconductor diodes to the milliammeter, you can measure AC voltage and turn it into an AC voltmeter . The circuit is shown in Figure s-38.
    In Figure 5-38, VD1 and VD2 form a half-wave rectifier. The four resistors in Figure a are separate multiplier resistors; the multiplier resistors in Figure b are
connected in series, and their effect is the same as that in Figure a. The "*" terminal in the figure is the common terminal. No matter what voltage is measured, there must be one in the two test leads.
The branch is connected to the “*” end,