Number 39

Number 39

The first post-TicoTronics TicoTron, formed out of good intentions and assembled from parts pulled from the basement. Here’s how it went down. At the beginning of April, 2013 we had just completed our first intensive TicoTronics course, producing what are arguably the first modular synthesizers to be assembled in Central America and pictures were hitting the web of of accomplishment – along with queries about when we’d be offering the next class and doing what we could to figure out alternatives – after all, I was leaving Costa Rica. Eventually, we decided to offer a one day class that concentrated on building a single module that could be either incorporated into the larger TicoTron system, or serve as a stand-along module, of the spirit moved. Looking to keep things simple, avoiding opamps and transistors as much as possible, I was examining CMOS circuits inspired by Stanley Lunetta and came upon a Benjolin-inspired Rungler circuit that could potentially fit the bill, using a 4015 IC triggered by a square-wave clock source. I happened to have a 4015 floating around, left over from a previous build, but the local electronics were out. Expecting 4 students, that wouldn’t be an option – so we ended up building a variation on the first TicoTron module instead. But I still had this 4015 and was kind of curious to see what I could do with it, since diy-synth documentation is… well, it’s a weird crowd, as far as I can tell. A couple days later, while packing for my return trip to NY, I took a quick break from packing to see what was up on the social network and saw that here was a benefit show being planned at the Upstate Artist’s Guild in Albany – cool place – played there like, 5 years ago now – and, unlike a majority of the other venues that I played at 5 years ago, this one’s still open. Realizing I could make use of this IC out of curiosity, finally use a couple circuits sitting in a box in my folks’ basement and do some good, I dropped a line to the event organizers, wondering if they’d be interested in me donating a synth to them as part of their fundraising efforts. They jumped at the opportunity. Well, I don’t know if they actually jumped, but the project was green-lighted.

On April 18, I took the flight north and subsequently spent the next few days hopping around the east coast via Chinatown busses, running errands. I returned Tuesday night around midnight and got to work – three days to go from a single IC and a couple junked proto-circuits into a functioning instrument, case included. The front panel was taken from the surplus stack of TicoTron panels – no problem. Anticipating a couple sketches made on a bus from Baltimore to NYC, I drilled my panel, populated it and went to work on the circuit – kind of a roundabout approach, but I figured why not build to the panel instead of designing the panel around the circuit. Call it a challenge. The 4015 required two inputs – a clock and a datastream. Using a 4093, I hacked together a simple clock circuit and plugged it direct to the clock input. Using the three other nand-gates on the 4093, I assembled a cascading nand-synth and plugged that into the data section of the 4093, figuring a modulated, chirping, semi-stable data-source would be more interesting than a static square-wave. Drawing inspiration from Ciat-Lonbarde’s Ol’ Mr. Grassi circuit, I added a resistor to each output of the 4015 and fed it back into the first input of the 4093’s three cascading oscillators – essentially creating an interdependent feedback network where the 4093 is supplying data to the 4015, which is in turn powering the 4093. The controls were chaotic – instead of simply changing a frequency, canging a potentiometer would interrupt the entire feedback system – kind of cool, actually – especially when monitoring the progress of this via LED’s on the front panel. To make things more interesting, I added a modified switched-capacitor lowpass filter to the output with a fixed resonance – making certain frequencies sound like bit-reduced crunch and others like heterodyned atmospherics. Impressive to see and hear, actually.

I finished everything on Saturday morning, about 20 minutes prior to leaving for the show in Albany. Not to go into details, but the box was a huge success at the show – happy to help, all said. May she serve her new owners well.


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