The present invention provides methods and apparatuses configured for transdermal electrical stimulation. The present invention describes single-use or limited-use TES apparatuses and methods of usingthem that include an integrated (e.g., flex-circuit) electrode assembly and controller apparatus including a waveform generator and power supply. The present invention aslo provides TES apparatuses including a cord or wire having current control circuitry and configured to connect a mobile computing device (e.g., smartphone or wearable electronics) to an electrode assembly. Finally, The present invention aslo describes intermediate apparatuses including a flexible circuit electrode assembly including a waveform generator but receiving power from a cable connected to a mobile computing device.