The PAiA 4750 module appears to be identical to the 2720-5 module as the manual had 4750 nomenclature while the PCBs 2720-5 nomenclature. The schematics are identical between the two manuals. The module consists of a sine wave oscillator and noise source. The sine wave output is unipolar while the noise output is bipolar. The 2720-5 kit was $20.95 in the 1976 catalog. There is no 4750 kit listed. The 4750 is listed in the 1980 catalog for a price of $21.95 for the kit or assembled for $30.00.
PAiA 4750 Control Oscillator-Noise Source User Manual
The module originally used a 500K potentiometer with a 470K resistor to make it more of a log contour. I simply replaced it with a 500K log taper.