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AM8018 Module - Precision Exponential VCA
 Overview This module is a new design based on the high quality
single VCA chip from Analog Devices - the SSM2018. The chip is available as a trimless version SSM2018T, and it is this chip I have used. The module provides a high quality VCA with audio and control voltage mixing, an
exponential response to CV's and a level monitoring LED. The specifications of the chip are:
117dB Dynamic Range 0.01% THD 140dB gain range
AM8018 Module The circuit follows the datasheet suggestion for a core VCA
design, and then adds an OPA2134 dual Op Amp for audio signal mixing on the input side and output buffering. An LT1013 dual Op Amp performs CV summing duties, whilst the trusty TL072 provides the LED monitoring of the signal output The VCA has the following front panel controls:
Signal Input Levels for 3 inputs (A, B and C) 3mm LED shows overall output level VCA Gain CV Levels for 2 inputs (CV1 and CV2)
There are 6x 3.5mm jack sockets mounted on the left hand side of the panel, these are:
3x Signal Inputs 2x CV Input Signal Output
Build Notes This simple VCA design goes together easily and there are no hard
to find parts and it only requires one trim operation to set the overall gain of the VCA to unity.
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