Variable manipulation element. The function of this element is to manipulatethe signal presented to it preserving the original nature of the signal.Manipulation here means only a change in numerical value of the signal. Forexample, an electronic amplifier accepts a small voltage signal as input andproduces an output signal which is also voltage but of greater magnitude. Thusvoltage amplifier acts as a variable manipulation element. It is not necessarythat a variable manipulation element should follow the variable conversionelement as shown in Fig. 4.2. It may precede the variable conversion elementin many cases. In case, the voltage is too high, attenuators are used whichlower the voltage or power for the subsequent stages of the system.