# My build progress

**URL:** <https://lookmumnocomputer.discourse.group/t/my-build-progress/345>\
**Category:** DIY STUFF\
**Created:** [March 1, 2020, 8:57pm UTC](https://lookmumnocomputer.discourse.group/t/my-build-progress/345 "2020-03-01T20:57:53Z")\
**Posts on this page:** 1\
**Showing post:** 2710

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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:** [February 18, 2021, 4:13pm UTC](https://lookmumnocomputer.discourse.group/t/my-build-progress/345/2710 "2021-02-18T16:13:41Z")

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Note that the 3340 sync inputs are slightly weird. The original CEM3340 datasheet has a discussion and some sample schematics, if you want more “normal” sync inputs, see here:

> [@AS3340 VCO /w hard/soft sync, FM modulation](https://lookmumnocomputer.discourse.group/t/as3340-vco-w-hard-soft-sync-fm-modulation/249/2):
>
> The AS3340 example circuit uses a higher pulse out pulldown, and the onboard zener is a bit different so you can use a slightly lower Vee series resistor, but it works just fine with the CEM3340 values. The sync inputs expect brief spikes, and the example schematics just use 1 nF capacitors on the way in, to turn pulses into spikes: EDIT: The 1222 performance VCO follows the example schematics, and routes the sync input via a 1 nF capacitor (C4). EDIT: I just noticed that [the CEM334…](http://www.bustedgear.com/images/datasheets/CEM3340-3345.pdf)

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