[sdiy] trouble driving cmos from modular signals

[Ullrich Peter]

Hi!

The problem with the 4017 could be that not the levels are the problem but the signal edges.
The 4017 needs fast edges to work properly. Slow rising signals will not work.

So a Schmitt trigger on the clock input could be necessary.
Something like a 40106 (Schmitt trigger inverter) - use two if non inverting is needed.

Ciao
Peter

http://www.ullrich.at.tt


-----Ursprüngliche Nachricht-----
Von: synth-diy-bounces at dropmix.xs4all.nl [mailto:synth-diy-bounces at dropmix.xs4all.nl] Im Auftrag von dan snazelle
Gesendet: Freitag, 14. September 2012 06:48
An: *SYNTH DIY
Betreff: [sdiy] trouble driving cmos from modular signals

normally when I interface a modular signal into a counter, say a +/-5volt VCO signal into a 40xx,  (in this case a 4017)


i put it through a resistor with a diode to ground, or a diode with a resistor to ground.
but i am working right now with a 4017 which WILL NOT 

see the VCO output unless I put it through a level shifter module first and add a bunch of gain.


i would LIKE to find a passive solution  to this predicament,  but I am not sure if that is possible.

(maybe 2 diodes and a resistor?)
                                                                                                                                                                                                            


THANKS FOR ANY HELP!!!



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