15V 7400 logic family??

A.S.P. ms20 at serv.net
Fri Mar 28 20:45:58 CET 1997

On Thu, 27 Mar 1997, John Speth wrote:

> At 11:17 PM 3/27/97 GMT, you wrote:
> >On Thu, 27 Mar 1997 08:40:37 -0800, you wrote:
> >
> >>I'm designing a nice and simple 2 channel sequencer and, of course, I'd
> >>like to make it small and easy to build.  Naturally I'm drawn to using CMOS
> >>digital ICs because 1) they allow supply voltage of 15V and 2) they consume
> >>next-to-nothing power under static conditions.  So I looked over the CMOS
> >>CD4000 family and found the functionality was kind of light compared to the
> >>classic TTL 7400 family.  
> >Perhaps a little lighter with respect to more hardcore computer
> >related binary stuff, but there are other devices that are *perfect*
> >for analog signal handling, such as analog multiplexors and
> >transmission gates.  Perhaps you could let us know what kind of
> >devices TTL offers that you'd like to emulate in CMOS.  Very often, a
> >simple combination of basic elements will yield what is desired.  And
> >as you say, power consumption is next to nothing, so a small increase
> >in package count will not seriously affect power supply design.
> Ok, the analog portion of the circuit is pretty simple.  I'll use a couple
> of CD4051's that will select 1 of 8 voltages from 2 rows of 8 pots and the
> 4051 outputs going to 2 opamps.  The TTL-like device I have my eye on is
> and would be the core of this sequencer is a 74161 (4 bit cascadable full
> synchronous binary counter).  I'm pretty sure that with the features I plan
> to design into this, I can use this chip with just several other "glue"
> chips as the engine that steps the sequencer.  I'm really bent on a lean
> design.  I don't want to have to fashion a fancy substitute using the
> CD4000 series just to make a synchronous counter.  

I'm surprised you're looking at such an old IC (74161).  You can use a
CD4516 as a counter, then you can use a CD4514 as a decoder, or a pair of
4051s and an inverter.

THe 4516 will let you count up or down, which is a feature I find really
useful. It also has parallel inputs, in case you want to jam some crazy
bits in and do strange, non linear sequencing.

> After giving it some thought, it will probably be easiest to simply use the
> 5V 74HC00 family with an onboard lower power 5V regulator.  My working pot
> voltage would then be 5V (so I won't blow the 4051's) and I'll amplify the
> selected pot voltage with the opamps to get it to the final ouput level
> that I need.

Hm... the sequencer I built uses 15V.  The output is then scaled to 10
with an opamp.


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