CEM3340: Difference between revisions

The '''CEM3340''' and '''CEM3345''' are a self contained [[VCO]], originally produced by [[OnChip Systems|Curtis Electromusic Specialties]]. With both [[exponential]] and [[linear]] control inputs and up to four output waveforms: [[triangle]], [[sawtooth]], [[square]], and [[pulse]] with voltage controllable [[pulse width]]. It has full temperature compensation making it extremely stable. Also included is provision for [[oscillator sync|hard and soft synchronization]] of the [[frequency]], and an output for easy adjustment of [[VCO high frequency tracking|high frequency tracking]].<ref name="3340dsdslong">[https://static.miraheze.org/sdiywikiwiki/1/1c/CEM3340-3345_long.pdf CEM3340/3345 data sheet]</ref>

The [[Digisound 80-2]] and [[Digisound 80-3|80-3]] are well designed and versatile analogue VCO and VCLFO.<ref>[http://www.soundonsound.com/sos/jan00/articles/digisound80.htm Digisound 80, Modular Synthesizer (Retro)], SOS Jan 2000 by Paul Nagle</ref><ref>[http://www.digisound80.co.uk/digisound/modules/80-2.htm 80-2 Voltage Controlled Oscillator]</ref> To prevent the IC being put under too much stress if/when the outputs are shorted, all outputs should have a series 1K resistor. The triangle wave output is unbuffered and should never be used to drive an output directly, add a J201 FET follower to buffer it.<ref>[https://www.modwiggler.com/forum/viewtopic.php?t=24134 Does the A SOL MC-202 modular kit work on the SH-101?], Mod Wiggler forum, Nov 2010</ref> A better sine output can be achieved by using instead the [[Thomas Henry]] [[VCO-1 waveshaper]].<ref>[http://www.birthofasynth.com/Thomas_Henry/Pages/VCO-1.html The VCO-1 Project]</ref><ref>[https://www.modwiggler.com/forum/viewtopic.php?t=143298 VCO/LFO PCB for CEM3340 chips], Mod Wiggler forum, Aug 2015</ref>