An electrotherapy unit includes a central processor, a digital force modutator connected to and controlled by the central processor, a voltage-increasing transformer, and two conductive pads connected to a secondary coil of the voltage-increasing transformer. The digital force modutator includes two pairs of transistors each having an input side connected to the central processor. The central processor controls conduction/non-conduction of the transistors. A loop for each transistor is connected to the power supply and the primary coil of the voltage-increasing transformer. A diode and a capacitor are connected in parallel between a collector and an emitter of each transistor. The diodes avoid damage to the transistors resulting from an electromotive generated by the primary coil of the voltage-increasing transformer. The capacitors reduce noise signals generated during switching operation of the transistors and the diodes. The capacitors provide bypass for high-frequency noise signals.