ODP: CMOS/TTL chip questions (was: Cmos Latch Octal)

[Roman Sowa]

I once connected 12V CMOS to 5VHC wia 100k resistor
And it has worked fine over the years (low frequency of course)
Input protect diodes in HC device in conjunction with resistor give 
the simplest solution for CMOS/TTL interconnect.

another point - 5V HC output will work fine with CMOS inputs
powered up to 7-9V with any circuitry

basically, there are many tricks depending on actual design

74138? use LS138 or HC138 and you need no buffer

and, of course, go get MSEE ;-)

Roman

> -----Oryginalna wiadomość-----
> Od:	Adrian Corston [SMTP:adrian at internode.com.au]
> Wysłano:	17 listopada 1998 23:18
> Do:	Ullrich at kapsch.net
> DW:	synth-diy at mailhost.bpa.nl
> Temat:	CMOS/TTL chip questions (was: Cmos Latch Octal)
> 
> Basically, I'm just learning this sort of thing, and my current project
> is trying to design a simple trigger sequencer to drive an old analogue
> drum machine. I have a working circuit, but I'm not sure if I'm doing
> it 'by the book' (for example, the 4040 CMOS counter output bits just
> connect straight into the 74138's A0-A2 inputs - do I require any
> buffering etc? is it ok to strobe the 74138's /E2 input from a 555 output
> which also steps the 4040?)
> 
> Any assistance in this area (even "go get an engineering degree" :-)
> is appreciated!
> 
> Thanks,
> 
> -- 
> Adrian Corston
> Internet Engineer
> Internode Professional Access