[sdiy] 4027 flip-flop weirdness

[Mike]

> At 12:30 PM 3/10/2009, Scott Gravenhorst wrote:
>
> >The debounce you describe - why the 10uF?  Is this for a switch?  I think
> >a schmitt
> >trigger following that might be better...  A capacitor/resistor (if I'm
> >visualizing
> >what you did correctly) will cause the signal to transit logic levels
> >slowly and when
> >the input is halfway between the IC's rails, it can "chatter" and do
> >naughtiness.
>
> According to the data book I  have the clock needs to transition in under
5
> us.  How exactly are you doing your debouncing?
>
This is a classic problem: too slow a debounce time contant and the input
spends too long in the indeterminate state. It can oscillate or pick up
noise and generate multiple triggers.

Options: If you want to use a long time constant - like to 'slug' double
pushes or seomthing like that, put a schmidt trigger circuit inverter
(40106), on the input. If that gets the polarity wrong, just use another of
the schmidts asa pure inverter. The input time constant will stay 'soft',
but the on/off transition at the output will be up to spec'.

||\/||ike