[sdiy] Delaying a pulse with a CMOS chip ?

[Colin Hinz]

On Tue, 18 May 2004, Ken Stone wrote:

>> Thks for the info you sent to me, i implemented it but without this
>> chip. It seems to work ! :)  Since the pulse goes to a 4516 counter,
>> i assume that i don't need the inverter ?
>
> Correct.
>
>> Or is there some special need for the CD40106 (or equivalant), for
>> instance is the input pin of this chip of a special kind that is
>> needed after the RC thing ? Does it need Schmitt Trigger input
>> to work well  (better stability of the voltage threshold) ?
>
> A schmitt will tidy up the waveshape, which is better when you are driving
> an edge triggered input. If it is a level sensitive input (e.g. a data
> input) it is not as critical. I do it without any form of buffering when
> using 4015 shift registers as I am connecting the delayed signal to a data
> input.
>
> however, if it works, it works.

Yes, for a single device, operating at a specific voltage and temperature.

Do you really want the (relatively mild) horror story? I wrote it up,
but snipped it for being excessively diversionary.

People who meet me in person assume I'm some sort of hippy freak,
which may in fact be true, but I do have a pretty conservative
philosophy to circuit design. Go figure......

Okay, enough rambling.

- Colin Hinz
  Toronto, Canada