Using an Arduino Micro-controller, this circuit displays the frequency spectrum of a guitar signal. The analog guitar signal is amplified and offset so it can be correctly read into the Arduino ADC to become a digital signal. This is accomplished via an OP AMP and a voltage divider. The Arduino runs the Fast Hartley Transform (FHT) algorithm, which is a Fast Fourier Transform on only real data and not complex data, on the signal. After the signal has been converted to a function of frequency, coefficients are assigned to each of the 16 bins that cover the frequency spectrum. The values of each bin are displayed on a 16x8 LED Matrix via a I2C interface.