Arduino based CV/Gate controller with four channels

With my first post on the Arduino based CV/Gate controller I implemented a single control channel using a single DAC. Now, using four TI LF398 sample-and-hold ICs, I multiplexed the DAC output into four control channels. I updated the Arduino sketch and managed to control all four outputs independently.

However, something that I overlooked is that the LF398 needs +5V and -5V, whereas I only have +5V available over USB. So the output voltage dropped considerably, from 5V (actually 4.8V) to about 2.3V. That is not nearly in the range that we need for the Control Voltages.

With an Intersil ICL7660 voltage inverter/doubler I was able to create the -5V. But the output current of the ICL7660 is not enough to drive the 4 sample-and-hold ICs.

So I have the four control channels, but not yet at the required output voltages. To be continued…

Update (18 October 2015): I completed the implementation of a four-channel CV/Gate controller.