An electromechanical device which uses a coil operated switching mechanism to convert a direct current input into a pulsating direct current output of the same value. The direct current input is periodically interrupted at the resonant frequency of a coil driven vibrating armature (reed). The resultant pulsating direct current output produces an inherent alternating current component necessary for ultimate purposes of transformation. It does not include a means of amplification or rectification. For items designed to operate over a wide and comparatively high frequency range and whose drive coil may be excited from either an alternating current or a direct current, see chopper, electronic.