Check Check. A few weeks ago a User was asking about sine wave generators- hurz beat me to the punch with a nifty little circuit of his own but not before I spotted this gem in a quick net search, and began constructing a model of it. This is a fairly simple to build test circuit for sound system set-up (recording studio, live gig, etc.) . Specifically it is intended to be used in place of a microphone for the vocal monitors. The two nodes I have highlighted on the scope would be where the two signal pins of your XLR jack are connected- the third goes to ground.
