# AO Noise Bells ,,,,,,,,,,,,,,, **URL:** \ **Category:** KOSMO MODULES\ **Created:** [November 15, 2020, 2:45am UTC](https://lookmumnocomputer.discourse.group/t/ao-noise-bells/2301 "2020-11-15T02:45:39Z")\ **Posts on this page:** 7\ **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:** [November 15, 2020, 2:45am UTC](https://lookmumnocomputer.discourse.group/t/ao-noise-bells/2301/1 "2020-11-15T02:45:39Z")
This is a percussion and drone synth module based on ideas presented in the 2015 Hackaday article “[Logic noise: More CMOS cowbell!](https://hackaday.com/2015/04/10/logic-noise-more-cmos-cowbell/)” by Elliot Williams. (See also [Cmos noise bell](https://lookmumnocomputer.discourse.group/t/cmos-noise-bell/1103) .) The PCB and front panel are Kosmo format but the same circuit could be implemented in Eurorack format, or other ±12V formats, with no changes other than PCB, panel, and jack dimensions. ![IMG_6415](https://global.discourse-cdn.com/free1/uploads/lookmumnocomputer/original/2X/a/a963b8dd4451ec7a589b608f51ddbe8170cb210c.jpeg) The module consists of two separate sections. One is a 2-oscillator circuit based on the “cowbell” section of the Hackaday article. The other is a 4-oscillator circuit, lying sort of halfway between the “cowbell” and “hi hat” designs and designed to use most of the IC functionality left over from the “cowbell” side. Whether it leans more toward bell or cymbal sounds I leave for you to decide. The two sections differ only in the number of oscillators and XORs used. Aside from a few component value changes, notably a larger capacitor allowing longer decay times, there are a couple of significant modifications to Williams’s design: - The 2-diode “VCA” has been replaced by a 4066 analog switch “VCA” as discussed in the article’s comments and at [http://files.electro-music.com/forum/viewtopic.php?highlight=diode+vca&t=23960](http://files.electro-music.com/forum/viewtopic.php?highlight=diode+vca&t=23960). - A switch has been added to bypass the EG/VCA section, sending the output of the final XOR straight to the output buffer. This allows using the module for noisy drones. Pots are used for variable oscillator frequencies and amplitude envelope decay rates. Schematics, Gerber files, BOM, build notes, and other information at [GitHub - holmesrichards/NoiseBells: Percussion module based on Hackaday CMOS Noise article](https://github.com/holmesrichards/NoiseBells) Video: [![](https://global.discourse-cdn.com/free1/uploads/lookmumnocomputer/original/3X/7/5/75381c04551d32e13e882c31fada82246742c724.jpeg "Noise bells") ](https://www.youtube.com/watch?v=vi7xciDVn3E) ~~Extra boards and panels should be up on [Tindie](https://www.tindie.com/stores/analogoutput/) early next week.~~ Sold out! ---
**Author:** ![Vumnoo](https://yyz2.discourse-cdn.com/free1/user_avatar/lookmumnocomputer.discourse.group/vumnoo/32/6942_2.png) [@Vumnoo](https://lookmumnocomputer.discourse.group/u/Vumnoo)\ **Post date:** [November 15, 2020, 8:45am UTC](https://lookmumnocomputer.discourse.group/t/ao-noise-bells/2301/2 "2020-11-15T08:45:53Z")
Enjoyed the video! Thankyou ---
**Author:** ![Dud](https://yyz2.discourse-cdn.com/free1/user_avatar/lookmumnocomputer.discourse.group/dud/32/610_2.png) [@Dud](https://lookmumnocomputer.discourse.group/u/Dud)\ **Post date:** [November 15, 2020, 8:52am UTC](https://lookmumnocomputer.discourse.group/t/ao-noise-bells/2301/3 "2020-11-15T08:52:29Z")
great realisation and explication, like allways 🙂 ---
**Author:** ![eric](https://avatars.discourse-cdn.com/v4/letter/e/898d66/32.png) [@eric](https://lookmumnocomputer.discourse.group/u/eric)\ **Post date:** [November 15, 2020, 9:43am UTC](https://lookmumnocomputer.discourse.group/t/ao-noise-bells/2301/4 "2020-11-15T09:43:49Z")
Hi, That’s cool. I’ll put it in my next PCB order. Checking the BOM I see this C1-C6: 100nF polystyrene (Tayda A-564) C14-C16: 100nF ceramic (Tayda A-564) A-564 are: # 100NF 0.1UF 100V 5% POLYESTER FILM BOX TYPE CAPACITOR I guess decoupling caps C14-C16 can use Tayda A-4008, or maybe even need to because of the footprints on the PCB. ---
**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:** [November 15, 2020, 1:17pm UTC](https://lookmumnocomputer.discourse.group/t/ao-noise-bells/2301/5 "2020-11-15T13:17:04Z")
Yeah, I used ceramics for decoupling caps, and boxes for the others. I’ll fix the BOM. Thanks for pointing it out. ---
**Author:** ![BratAttack](https://yyz2.discourse-cdn.com/free1/user_avatar/lookmumnocomputer.discourse.group/bratattack/32/14401_2.png) [@BratAttack](https://lookmumnocomputer.discourse.group/u/BratAttack)\ **Post date:** [April 21, 2021, 9:30pm UTC](https://lookmumnocomputer.discourse.group/t/ao-noise-bells/2301/6 "2021-04-21T21:30:44Z")
Long day at work. Time to assemble some bells 🙂 ![Untitled](https://global.discourse-cdn.com/free1/uploads/lookmumnocomputer/original/2X/b/ba2f493d7864f0b57ab7850ec9755a4df3bdd93a.jpeg) EDIT: Litany incoming… ---
**Author:** ![saint\_et\_moudulard](https://yyz2.discourse-cdn.com/free1/user_avatar/lookmumnocomputer.discourse.group/saint_et_moudulard/32/12683_2.png) [@saint\_et\_moudulard](https://lookmumnocomputer.discourse.group/u/saint_et_moudulard)\ **Post date:** [April 30, 2021, 1:16am UTC](https://lookmumnocomputer.discourse.group/t/ao-noise-bells/2301/7 "2021-04-30T01:16:19Z")
So nice design, great circuit !! And always good explications in videos ! I have add a vactrol on the decay pot for a cv control, It work enough good ! 🙂