Differential pulse voltammetry (DPV) and related techniques are examined. The proposed treatment is valid for any pulse method performed at stationary plane or spherical electrodes in the case of simple reversible reactions with both redox forms soluble in solution. The behaviour of the waves in DPV depends on the ratio R of the duration of the impulses to the duration of the steps of the potential staircase on which the impulses, of amplitude Delta E, are added. The waves behave as in differential pulse polarography performed at a renewable mercury drop electrode only if R > 0.8. Square-wave voltammetry, where R = 0.5, and differential staircase voltammetry, where Delta E = 0, appear as particular cases of the DPV. All these methods can be analysed satisfactorily in a simple way.