Abstract: A circuit arrangement for producing a composite waveform comprises a multiplexer controlled by a logic network for successively energizing a load with an aperiodic voltage from a switching circuit and one or more sine waves or other periodic voltages continuously produced by respective oscillation generators. The logic network includes a cycle counter stepped by a selected oscillation generator for terminating the transmission of its output voltage ater a preset number of cycles. An analog comparator, continuously receiving a d-c potential from a manually settable voltage source and a sawtooth voltage from each oscillation generator, emits an enabling pulse to the logic network upon detecting a coincidence between the sawtooth voltage of a selected generator and either the manually selected d-c potential or the sawtooth voltage from another selected oscillation generator.