This simple module could be used to display DC or AC voltages by means of an illuminated moving coil meter with mirror scale.
The display range is 0...+10V (resp. -5V...+5V in the offset mode) and the module features 3 different measuring methods that can be selected with a toggle switch:
|Picture via Matrixsynth|
Direct Mode: In this mode the incoming voltage is lead to the meter without additional electronic modification.
This mode is used to display positive DC voltages, e.g. ADSR (A-140/141/A142), MIDI-to-CV (A-190/191), positive random voltages (A-149-1), foot controller (A-177), Gate/Clock signals.
Offset Mode: In this mode +5V are added to incoming voltage before it reaches the meter.
Zero volt input correspond to the middle position of the display needle (i.e. +5V read out).
This mode can be used to display positive and negative voltages, like for example a slowly swinging LFO (A-145/146/147), A-148 Sample&Hold, bipolar Random Voltages (A-118), A-174 Joystick, A-178 Theremin, A-179 Light Controlled CV source.
The measuring input is available as a triple multiple so that the signal can be used in the system simultaneously.
An LED lights up if a negative voltage appears at the measurement input.
I don't own an A-197... The module seemed useless to me at first because of the lack of possibilities, and i was (and still am) thinking about buying an oscilloscope at some point.
Since this module is no longer available it will be hard to find one nowadays.