[sdiy] 4042 latch question

[harrybissell]

Hi Dave...

I don't think the diode would work... it would have to be in polarity
to allow the higher source to feed voltage from the pullup to the output
(effectively making an open collector output... but with an upper transistor
in the totem-pole that would reverse bias... )

H^) harry

Dave Magnuson wrote:

> At 01:33 PM 12/1/02 +0100, mark verbos wrote:
> >You could try putting some resistors to the + supply in betweent he
> >chips. Maybe it will be pulled up to switching between +3 and +8 insted
> >of ground and +5 then, That woudl work I think.
> >
> >mark
>
> I've never tried Mark's idea, but it may work....
>
> But:  common sense tells me you would also want a diode between the
> lower-voltage chip and the pull-up resistor to prevent damage
>
> Dave
>
> >
> >Peter Grenader wrote:
> >
> >>You've got to be kidding me.  So it ain't so!  To quote Bart Simpson
> >>
> >>"Oh Mee-aan"
> >>
> >>You mean i'm going to have to install...transistors????  i hate having to
> >>duts with transistors.  Would a 4050 see that 5 volt high? (its quoted as
> >>being able to do voltage converstions).
> >>
> >>thanks for this and let me know,
> >>
> >>P
> >>
> >>
> >>Paul Schreiber wrote:
> >>
> >>>CMOS switches at .3VCC and .7VCC. So for a +12V system, the HI threshold is
> >>>8.4V.
> >>>
> >>>Paul S.
> >>>
> >>
> >>
> >>>>if it's running off of +12, is there any reason the latches will not
> respond
> >>>>to an input where the high state of the D inputs only goes to 5 volts?
> >>>>
> >>>>
> >>>
> >>
> >>
> >>
> >
> >
>
> Resonant Frequency:
> resfreq at hoohahrecords.com
> http://www.hoohahrecords.com/resfreq/index.html