# Glitches or ringing on the pulse output of the AS3340 and CEM3340

**URL:** <https://lookmumnocomputer.discourse.group/t/glitches-or-ringing-on-the-pulse-output-of-the-as3340-and-cem3340/752>\
**Category:** DIY STUFF\
**Created:** [April 28, 2020, 8:32am UTC](https://lookmumnocomputer.discourse.group/t/glitches-or-ringing-on-the-pulse-output-of-the-as3340-and-cem3340/752 "2020-04-28T08:32:52Z")\
**Posts on this page:** 1\
**Showing post:** 2

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**Author:** ![fredrik](https://yyz2.discourse-cdn.com/free1/user_avatar/lookmumnocomputer.discourse.group/fredrik/32/682_2.png) [@fredrik](https://lookmumnocomputer.discourse.group/u/fredrik)\
**Post date:** [April 28, 2020, 9:42am UTC](https://lookmumnocomputer.discourse.group/t/glitches-or-ringing-on-the-pulse-output-of-the-as3340-and-cem3340/752/2 "2020-04-28T09:42:00Z")

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@Caustic mentions it briefly here (later updates):

> [@AS3340 VCO /w hard/soft sync, FM modulation](https://lookmumnocomputer.discourse.group/t/as3340-vco-w-hard-soft-sync-fm-modulation/249):
>
> Hey yall, I got some time today to take a look at my old VCO build. Couldn’t figure out what the hell was wrong with it, so i just built it again. Rather than just be boring, i also attempted to add the other features that were not included in the original stripboard design. Things like soft / hard sync and FM modulation. I dont really have the capacity to check that this works right as is, i did my best given the diagram in the datasheet and some example schematics on Electric Druid. All i ca…

And yeah, the raw pulse output works for a handful of audio octaves, but seems somewhat broken by design beyond that (hence things like the AS3340 hybrid that I haven’t used).

(decoupling at VEE instead of −12V seems wrong, btw, pretty sure you want a low impedance path to the capacitor)

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