Abstract: Apparatus and associated methods relate to a symphonic pulsed electromagnetic field (PEMF) therapy device operably coupled to a handheld solenoidal coil. In an illustrative example, the symphonic PEMF therapy device may be configured to drive the handheld solenoidal coil to generate a time-varying symphonic PEMF. The symphonic PEMF may, for example, be generated in response to activation of a predetermined symphonic frequency profile (PSFP) selected from a library of PSFPs. Each of the PSFPs may include a frequency set of, for example, at least 50 frequencies. The frequencies may, for example, include frequencies from at least four decades starting at 10 Hz. The PEMF therapy device may advantageously generate symphonic PEMF in response to user input selection, for example, of a predetermined medical therapeutic and/or a non-medical optimization effect.

Abstract: A remotely controlled microphone amplifier has a first amplifier stage with a variable gain circuit operatively connected in the overall feedback loop of the first stage for controlling the gain in first increments. A unity gain second amplifier stage has variable attenuator operatively coupled between the output of the first amplifier stage and the input of the second amplifier stage. The variable attenuator controls the input to the second stage in second increments less than the first increments. The overall gain is linearly adjustable and varies in equal increments.