Several tools have emerged as community favorites for generating and managing these specialized files:
A small, cheap digital audio amplifier (such as a Lepai or Nobsound mini amp) can take the signal from your laptop's headphone jack and boost the power. You then connect the speaker outputs of the amplifier to a step-up transformer, which converts the low-voltage, high-current speaker signal into a high-voltage, low-current e-stim signal. Commercial E-Stim Boxes with Audio-In estim audio generator top