CGS mixer and ETI 4600 VCA

The CGS mixer and VCA module is the combination of two sub modules, a mixer and a voltage controlled amplifier.

For the construction details of the mixer, see the CGS DC mixer (previous version). In this case, only two inputs are used, and there is no overal gain control. The output is fed both to the output socket and the switched input of the the VCA signal input (normalised connection).

The VCA itself is the VCA/Ring Modulator from the International 4600 (Maplin 4600).

Two have been constructed, and there is a third waiting for a panel. Two of these VCA boards were hand etched, and the third was one of the boards from the 3800.