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Subject: More Korg NJM 2060 VCF chip madness..

From: bperkins211@...
Date: 2016-02-13

Managed to get the NJM 2069 VCF chip whittled down to minimum parts needed to run it and to get it to do more...




Sound Demo-


https://youtu.be/fExbdRKDSzo




and some explanation of the controls...



https://youtu.be/ZAUnktgci9Y




I noticed I made an error about what was said regarding the LFO ramp waves.. the scope will show an up ramp wave but it sounds like a down ramp.. that is because of the VCF response to voltages is +5v will totally cutoff the frequencies.. 0v lets all the freq. thru.  So basically the VCF inverts CV's from what you'd normally expect.

Which is my next challenge.. using a SSM2056 ADSR chip to get an EG for the VCF.  But for it to work, I must invert the ADSR's V+ output (or I should just have the inverter right before the VCF)..  I am hoping a simple differential opamp circuit will do the trick.   To trigger the gate, I will again try to use the same MIDI interface I used in the vid to send a +5v trigger/gate to the SSM2056 whenever any MIDI note ON is detected..  and hopefully at a minimum, it stays triggered/gated until I release the last note held.


/Blaine