Tuesday, September 8, 2015


Wow, been a busy summer! been slowly chipping away at this waiting list i have accumulated over the past few months. to everyone who has waited, thanks for hangin' in there! i'm doing the best i can to get to all of you. that said, i am not adding to the list until i can get through some first.

This project was a commission for an artist who needed a circuit to add to one of his installation pieces. the intent was to have the circuit and all of its hardware be removable from the temporary enclosure, so that it could be installed in the installation piece at a later time. this seemed easy enough in theory, but was actually pretty complicated. it is hard to know what vulnerabilities exist in the wiring when you are looking at it through someone else's eyes.  i did my best to make things as strong and clean as possible. that in itself was a real challenge since the circuit was pretty complex for the amount of hardware it uses. 

The piece was designed to have maximum sonic flexibility through the use of only two analog joysticks. this was because in the art-installation application, the analog joysticks would be the only thing to be used. the customer was OK with having simple functions, since there are really a limited number of things you can do with four joystick axis(four), but i convinced him that i could cram some more functions in to it that could be toggled by the joysticks' center push switches, and still be small enough to fit into a small enclosure. i ended up biting off more than i could chew, as always, but after some backtracking, we came up with a good signal path that had enough flexibility that it was not boring, but not so much complexity that the enclosure would have to be substantially larger. 

This project took a lot of back and forth. over the past few months that i have been working on a commission basis, i have really been learning a lot about communication, and it has really been great. i really feel like i am getting better and better at giving people what they want, and whining less about why it is difficult for me to do. anyway, back on topic. it was really great to work with this particular artist and talk with him on the phone. that rarely happens. in fact, lately it has been rare that i work for someone who lives in the US!

Anyway, back to the circuit. the circuit consists of one square-wave VCO that is fed to a 12db lowpass filter with a fixed resonance. the signal is then sent to a VCA, and finally a PT2399 delay before being sent to the power-amp and output section. there is also one triangle LFO that can be toggled on or off to modulate the VCO or VCF. the LFO can modulate the VCA in a kind of interesting way. on one joystick axis, the VCA can be controlled manually from center(full-off) to one outer direction, and in the other direction from center, can control the depth of the LFO to the VCA. this was a pretty fun circuit to design and i will definitely be using it again someday. the center-push switches of the two joysticks are hooked up to a counter chip that sequences through the LFO modulation combinations, as well as turns the PT2399 on or off, and switches the LFO range to high or low. in all, there are 16 different mode combinations possible. there are four mode LEDs that indicate when a mode is active or not. the VCA also has a manual gate switch that opens up the VCA to full when pressed. the volume control knob has the power switch built in, so when the master volume is turned all the way down(counter-clockwise), the power clicks off. i also added CV inputs. the CV inputs simply bypass the positive rail to the joysticks, so the joysticks act as threshold controls for the CV inputs.

Because this was only to be a temporary enclosure for the circuit, i used an enclosure from my NT series. i had an extra box from the NT01 series, so i used it. it was a really good fit too. 

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