[sdiy] 4042 latch question

[Scott Gravenhorst]

I think this is not a good idea.  Perhaps you could get the "high" a little
higher, but you may also pull the low up too.  I've tried things like this in
the past and found they result in marginal performance at best.  If it works at
all, this kind of thing is likely to cause an annoying intermittent condition.
 I think the level translator ICs suggested are the best bet, or if only one
input needs to be conditioned, you should be able do this with 2 NPN
transistors (I know, there's the "duts" factor...).


Dave Magnuson <resfreq at hoohahrecords.com> 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

=========================================================  
- What good are laws that only lawyers understand?
- Government: The other religion.
- The media's credibility should always be questioned.
- Thankfully, insects are rather small.

-- Scott Gravenhorst | LegoManiac / Lego Trains / RIS 1.5
-- Linux Rex         | RedWebMail by RedStarWare
-- FatMan: home1.GTE.NET/res0658s/FatMan/
-- NonFatMan: home1.GTE.NET/res0658s/electronics/