A microprocessor-based system for measuring low-frequency (less than 100 Hz) electrical noise power spectra is described. The main function of the microprocessor was to determine the noise autocorrelation function using simple ''one bit'' autocorrelation arithmetic, subsequent Fourier transformation to find the power spectra being done on a larger computer. Given that such larger computing facilities already exist, this system is much less expensive than more conventional analogue techniques. We illustrate the way in which this system was implemented to measure current noise in insulating polymers.