# Kassutronics variable shape LFO **URL:** \ **Category:** KOSMO MODULES\ **Created:** [May 11, 2022, 3:47pm UTC](https://lookmumnocomputer.discourse.group/t/kassutronics-variable-shape-lfo/5000 "2022-05-11T15:47:30Z")\ **Posts on this page:** 5\ **Page:** 1
**Author:** ![analogoutput](https://yyz2.discourse-cdn.com/free1/user_avatar/lookmumnocomputer.discourse.group/analogoutput/32/29663_2.png) [@analogoutput](https://lookmumnocomputer.discourse.group/u/analogoutput)\ **Post date:** [May 11, 2022, 3:47pm UTC](https://lookmumnocomputer.discourse.group/t/kassutronics-variable-shape-lfo/5000/1 "2022-05-11T15:47:30Z")
This is a dual LFO synth module in Kosmo format, based on a [Kassutronics design](https://kassu2000.blogspot.com/2015/10/variable-waveshape-lfo.html). There are three outputs for each LFO. Depending on the shape pot setting these provide ramp, asymmetric triangle, symmetric triangle, or sawtooth waveforms; sine or skewed “sine” waveforms; and narrow, square, or wide pulse waveforms respectively. ![bitmap](https://global.discourse-cdn.com/free1/uploads/lookmumnocomputer/original/3X/4/4/443841d0eb20b794bd2a1e6431b1e8d6670983ba.jpeg) ![DS1Z_QuickPrint13](https://global.discourse-cdn.com/free1/uploads/lookmumnocomputer/original/3X/4/4/44da9ae6918b96803c835d5289cc03344418525c.png) ![DS1Z_QuickPrint14](https://global.discourse-cdn.com/free1/uploads/lookmumnocomputer/original/3X/7/a/7a109ae8698fa138686b35e3ec472d3a82c3bb27.png) I replaced the original JFET-based tri to sine section with a differential BJT pair one. A few problems on the first run PCBs but they’re fixable with some kludging. Some mistakes of mine, and a couple of problems with the Kassutronics circuit. I made corrections to the PCB but have not tested the corrected version. I also updated design of the front panel, which should say “Kassutronics” rather than “Analog Output”. Schematics, KiCad design files, Gerbers, and documentation in the GitHub repo: [GitHub - holmesrichards/kdlfo: Shape variable dual LFO synth module in Kosmo format](https://github.com/holmesrichards/kdlfo) ---
**Author:** ![analogoutput](https://yyz2.discourse-cdn.com/free1/user_avatar/lookmumnocomputer.discourse.group/analogoutput/32/29663_2.png) [@analogoutput](https://lookmumnocomputer.discourse.group/u/analogoutput)\ **Post date:** [August 20, 2022, 11:35am UTC](https://lookmumnocomputer.discourse.group/t/kassutronics-variable-shape-lfo/5000/2 "2022-08-20T11:35:14Z")
[![](https://global.discourse-cdn.com/free1/uploads/lookmumnocomputer/original/3X/4/6/46f601b5031b6ef5b999ed5a50f9dd10ddb0837e.jpeg "Kassutronics dual LFO") ](https://www.youtube.com/watch?v=Oh2Ix0G7Luk) ---
**Author:** ![BenRufenacht](https://avatars.discourse-cdn.com/v4/letter/b/ba8739/32.png) [@BenRufenacht](https://lookmumnocomputer.discourse.group/u/BenRufenacht)\ **Post date:** [April 12, 2023, 3:16am UTC](https://lookmumnocomputer.discourse.group/t/kassutronics-variable-shape-lfo/5000/3 "2023-04-12T03:16:44Z")
I had a run of these made from the latest Gerber’s, and found that you need to re-fill your ground plane on one side of the board after the addition of the 200R resistors. I still managed to get it working with some bodging. ---
**Author:** ![analogoutput](https://yyz2.discourse-cdn.com/free1/user_avatar/lookmumnocomputer.discourse.group/analogoutput/32/29663_2.png) [@analogoutput](https://lookmumnocomputer.discourse.group/u/analogoutput)\ **Post date:** [April 12, 2023, 3:50am UTC](https://lookmumnocomputer.discourse.group/t/kassutronics-variable-shape-lfo/5000/4 "2023-04-12T03:50:58Z")
Yikes, very sorry about that. The PCB and Gerber files _should_ be OK now. ---
**Author:** ![BenRufenacht](https://avatars.discourse-cdn.com/v4/letter/b/ba8739/32.png) [@BenRufenacht](https://lookmumnocomputer.discourse.group/u/BenRufenacht)\ **Post date:** [April 12, 2023, 4:12am UTC](https://lookmumnocomputer.discourse.group/t/kassutronics-variable-shape-lfo/5000/5 "2023-04-12T04:12:56Z")
No worries. A smart person would have checked them over before ordering. It did say they were not tested.