Monday, February 13, 2012

A-197 Analog Meter

Another A-100 module that was discontinued a few years ago is the  A-197 Analog Meter.

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
Full Wave Rectifier: This mode is normally used to display audio signals resp. AC voltages. The incoming signal is rectified and smoothed with a low pass filter.

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.