In electrical measurements and research work it is frequently necessary to have available a source of e.m.f. having a sine wave form. It is also desirable to be able to produce electrical wave forms having special contours. Existing means for producing special e.m.f. wave forms have serious limitations. By utilizing a continuously varying capacitance, means are developed whereby a pure sine wave, as well as special forms, may be produced. Filtering is not required. The theory underlying the production of any desired wave form is outlined. Factors which tend to modify the resultant wave form are pointed out.