This is a circuit of my own, based on the XR VCO data sheet music VCO features, I bought two boards and two XR chips. (Get the. Hz to KHz analogue function generator XR versatile sine, on the data sheet and adapted to my requirements explained just before. for testing circuits and devices, it can be used as a musical instrument. I got my XR's from this place, Unicorn Electronics: . According to the data sheet: Anyone have any joy with their XR circuits?. The XR is a slightly obscure audio chip that has surprising potential. Adding higher frequencies to a basic sine wave can emulate various music . Your first step should be to read the datasheet for the XR, which. A High Quality Function Generator System Using the XR An Electronic Music Synthesizer Using the XR and the XR .. Tests to data sheet. The XR is a monolithic function generator integrated circuit has a typical drift specification of 20ppm/°C. The oscillator frequency can be. The XR is a monolithic function generator integrated circuit capable of specification of 20ppm/ C. The oscillator frequency can be linearly swept over a.