Electrochemical deposition can produce interesting patterns ranging from random fractals to orderly dendrites. We have studied the electrical signals due to the deposition of Zn ions in a cell with ${\mathrm{ZnSO}}_{4}$ electrolyte. In the dendritic regime, the current (voltage) exhibits periodic oscillations with constant applied voltage (current). The frequency is proportional to the applied voltage V and the electrolyte concentration n. We relate this behavior to the side-branching nature of the dendrites.