Estim Audio Generator

For mobile users, apps like StimPlayer (Android) or using a signal generator app (like "Signal Generator - Tone Gen") can turn your phone into a portable estim audio generator. Warning: Phone headphone jacks have very low voltage. You still need your power box connected via line-in.

# Pseudo-code for a 100 Hz pulsed tone with 20 Hz amplitude modulation
import numpy as np
import soundfile as sf
fs = 48000  # sample rate
duration = 60  # seconds
carrier_freq = 100  # Hz
mod_freq = 20  # Hz
mod_depth = 0.8 estim audio generator
t = np.linspace(0, duration, int(fs * duration))
carrier = np.sin(2 * np.pi * carrier_freq * t)
envelope = 0.5 + mod_depth * 0.5 * np.sin(2 * np.pi * mod_freq * t)
signal = envelope * carrier For mobile users, apps like StimPlayer (Android) or
| Issue | Consequence |
|-------|--------------|
| Clipping / DC offset | Sharp pain, skin irritation |
| High-frequency harmonics (>5 kHz) | No effect, wasted power |
| Low sample rate (<22 kHz) | Aliasing of pulse edges → unpredictable sensation |
| Unbalanced stereo | One channel drives both electrodes → no differential effect | # Pseudo-code for a 100 Hz pulsed tone