[sdiy] CMOS chip questions

Scott Gravenhorst music.maker at gte.net
Sat Jul 18 19:01:05 CEST 2009


"David G. Dixon" <dixon at interchange.ubc.ca> wrote:
>> well i meant in a situation where you are trying to replace 74 TTL with a
>> higher voltage CMOS compatible TTL.
>> 
>> i suppose i should just learn to design with actual 5 volt 74LS
>
>I think the most convenient way to go when mixing digital and analog is
>simply to add a 5V supply to the board for digital IC's with 78L05.  Then
>you can use whatever digital IC's are best for a given application, and you
>don't need a stand-alone 5V supply.
>
>Of course, the gurus may beg to differ.  I'd be interested in hearing the
>arguments against this notion.

I would agree with that and I think there's quite a bit of gear out there designed like
that.  The PAiA FatMan is weird, but still consisitent with that having +8 & -12 for
analog stuff and +5 for digital (it has an MPU for MIDI).  +5 should allow interfacing
stuff like PICs to whatever you're doing.

-- ScottG (who is not yet a guru)
________________________________________________________________________
-- Scott Gravenhorst
-- FPGA MIDI Synthesizer Information: home1.gte.net/res0658s/FPGA_synth/
-- FatMan: home1.gte.net/res0658s/fatman/
-- NonFatMan: home1.gte.net/res0658s/electronics/
-- When the going gets tough, the tough use the command line.



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