Abstract: A scale removing or preventing device can send a signal to a hollow body containing a fluid through a wire wound around the hollow body. The device includes a signal generator for generating a signal and a signal modulator for modulating the signal. The signal has a continuous sinusoidal wave form having a parametric representation and a frequency cycle, and a plurality of parametric pieces joined together at respective switching points in the frequency cycle, wherein the first derivatives of the parametric representation of the wave form at the respective switching points are continuous or discontinuous. The provision of a plurality of switching points with continuous or discontinuous first derivations and/or zigzag patterns over the entire signal increases the sudden momentum to the deposition molecules of the scale in each frequency cycle, and thereby increases the mobility of the water scale and removes the scale more effectively.