[sdiy] trouble driving cmos from modular signals

[Tom Wiltshire]

Peter could well be right about it being speed not levels that is causing the problem.

However, if it were levels, you might be able to make it work by putting a voltage divider between the rails on the input, and then feeding that with a diode - biasing the input to a midpoint value essentially. It's dirty but it can work, especially on 4000 series CMOS.

HTH,
Tom

On 14 Sep 2012, at 07:24, Ullrich Peter wrote:

> 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!!!
> 
> 
> 
> _______________________________________________
> Synth-diy mailing list
> Synth-diy at dropmix.xs4all.nl
> http://dropmix.xs4all.nl/mailman/listinfo/synth-diy
> 
> The information contained in this e-mail message is privileged and
> confidential and is for the exclusive use of the addressee. The person
> who receives this message and who is not the addressee, one of his
> employees or an agent entitled to hand it over to the addressee, is
> informed that he may not use, disclose or reproduce the contents
> thereof, and is kindly asked to notify the sender and delete the e-mail
> immediately.
> 
> 
> _______________________________________________
> Synth-diy mailing list
> Synth-diy at dropmix.xs4all.nl
> http://dropmix.xs4all.nl/mailman/listinfo/synth-diy