A DIY Ring Counter based on Ken Stone's Gated Comparator circuit.
My inspiration for this module was Grant Richter's Wiard Noise Ring - a random CV generator with a form of memory. While I liked its ability to capture an eight note sequence, I found it hard to control and wanted some method to reliably input my own data.
I first thought an analogue shift register - a chain of sample + holds - might provide the solution. Thanks to a prod in the right direction from Matthias of Fonitronik, I discovered Scott Stites' Klee sequencer and later Rob Hordijk's Rungler and Ken Stone's digital shift register circuits.
Using a CMOS chip like the 4015 or 4021 won't allow you to sample your own CV stream, but the end result is the same. A series of zeros and ones is converted into a stepped CV via a DAC, in this case an R/2R network. Feeding the last stage of the shift register back to the input allows you to hold a sequence. Here's how it sounds:
I built Bitsy as a companion to the Wogglebug, which provides the clock and data, via its burst output. Like the Klee, it can also be programmed via a sequencer or manual gates. To simplify the design, I left out the input comparators of Ken Stone's circuit. A switch is used to manually hold a sequence. The last stage is also available, allowing VC over new/ old data selection via a sequential switch like the Doepfer A-151. An LED reflects the voltage level.
I used the DIY Layout Creator to plan my perfboard and a 6HP Makenoise blank as faceplate. This was the first time I'd made a parallel board, which meant using wire connections for the jacks etc. However, the benefit of this was I didn't have to be totally accurate when drilling holes.
Thanks to Matthias for the hint and to the designers of the original circuits which inspired this project!