The A-171 is a voltage controlled slew limiter, otherwise known as a portamento controller or integrator. Whenever there is an abrupt transition in the voltage present at the input, the slew limiter works as an integrator, slowing down the transitions in the output signal, so that abrupt transitions are sloped.
The steepness of the slope is governed by the rate control. As well as manual setting of this slope, the A-171 also gives you the possibility of voltage control of the slope’s gradient by patching in an appropriate voltage to two CV inputs, one of which has an attenuator for level adjustment. Two LED’s serve as status indicators to show the relative amounts of positive and negative signals at the output.