It produces three types of signal: white noise, colored noise, and random voltage. White and colored noise can be used as audio sources, and also, in conjunction with a sample and hold module, as control voltages, and the random voltage is a useful source of voltage control, especially for its low frequency content.

The A-118 gives you the ability to mix the relative amounts of Red (low frequency component) and Blue noise (high frequency component) in the colored noise output. There are knobs to control the rate of change and amplitude of the random voltage, and two LEDs indicate the state of the voltage at any one time.

Important notes:

After power on it takes a few minutes until the two noise signals and the random signals are generated. The module is not faulty when after power on the signals do not appear immediately !
The level of the random voltage changes with the settings of the Blue and Red controls. Especially the Red control affects the random voltage level (which is derived by low pass filtering from the colored noise signal) because the Red control changes the share of the low frequencies in the colored noise signal. The effect of the Blue control is much smaller because it changes the share of the high frequencies in the colored noise signal which are filtered out by the low pass of the random circuitry. At certain combinations of the control positions even clipping of the random voltage may occur (e.g. with Red and Level fully CW).

Similar modules:

    A-117 Digital Noise
    A-118-2 Noise/Random/S&H/T&H (slim version) 
    A-149-1 Quantized/Stored Random Voltages
    A-149-4 Quad Random Voltages

Remark: Module A-118 has been be renamed to A-118-1 to distinguish it better from other modules of the A-118 series (e.g.  A-118-2 )