Part 4 in the series on building a Lunetta synth with a Quad NAND CMOS chip. Now, we add a closed feedback loop through all NAND Logic nodes on the chip back to the first one. The result is an unpredictable, wild, and almost insane gate modulation.
While our Lunetta synth circuit made the best of gated noise, we now concentrate on creating gated mayhem. To achieve this, we connect all of the four nodes on the CD4093 Quad NAND CMOS chip in a feedback loop.
The concept is fairly simple to grasp. We let all output Y nodes modulate the next A input node on the chip. The last output node (4Y) then loops back into the first input (1A). The result is totally unpredictable. Here’s how the messy schematic demo looks like.
I took the liberty to add a smaller 10k resistor on the final NAND node. You can experiment with different capacitor and resistor values all you want. In fact, this is what we plan to do in our next part. Instead of using fixed resistors, we replace those with light dependent resistors. The result is a highly playable and enjoyable Lunetta noise synth.