Abstract: A power supply includes a DC/AC inverter and an AC/DC converter connected in a loop such that a DC output of the AC/DC converter is connected to a DC input of the DC/AC inverter and an AC output of the DC/AC inverter is connected to an AC input of the AC/DC converter. Another AC output of the DC/AC inverter is available to provide power to a load.

Abstract: A system for playing music includes an guitar with two audio output channels, a cable to connect to the two output channels to an amplifier, an amplifier having two channels, an effects apparatus, and a guitar tuner mounted within the guitar. A looping circuit is connected to record instrument performances and play a looped playback of the performance, permitting the performer to accompany his earlier performance. Multiple channel looping circuits are provided. A guitar strap is provided with a vocal microphone that is connected through the strap end for amplifying the vocal signal. An alternate guitar strap includes an instrument input, an amplifier, battery and speaker positioned near the player's ear.