Module A-176 (Control Voltage Source) provides three voltage sources, to use wherever an extra CV is required. The top two voltage sources (CV 1 and CV 2) have controls for coarse and fine control of the voltage output; the third source (CV 3) just has the one control.
The range of the voltages output can be preset, either to 0 to +5 V or to -2.5 V to +2.5 V depending on your likely requirements. There is a jumper on the circuit board for each of the three voltage sources.
A typical use for the module would be to provide fine as well as coarse tuning for an A-110 standard VCO, (which, unlike the A-111, only has one tune control). 
In general, this module will be useful whenever you need a manually controllable CV on a module which doesn't itself have a built-in control.

For more detailed information please look at the English user's guide: A176_man.pdf