A system and method for applying a low strength, low frequency magnetic field therapy to biological tissues. A coil is excited with a low frequency oscillating current, e.g., 10-1000 Hz. The coil is, e.g., 5-200 turns, having a diameter of 2-20 mm, and produces a magnetic field strength of about 0.01-5 mTelsa at a distance of 1 cm from the coil, or a cover over the coil, into the tissue. The current is preferably controlled by a smartphone or other programmable device controlled by a downloadable app in accordance with a PEMF program which may be separately downloaded or updated, and may be provided through an audio jack. Alternately, a digital interface and/or wireless interface may control the current. An app on the smartphone may be used to control the frequency, amplitude/envelope modulation, waveform, duration, etc. of the oscillation. The coil may be in mineral housing with a simple filter, and TRRS-type audio jack.
