The easiest way to accomplish this is to apply a potential across the entire tube and tap the dynode voltages off a voltage divider, as shown in Figure 4-13.

Connected to the other input of the error amp is the midpoint of a voltage divider. We'll come back to this later.

Capacitor voltage divider is the voltage sensor. The influence of stray capacitor to measurement is discussed, and the influence of transient element to the divider is analyzed.