Fw: DIY_EFI Digest V5 #122

[Gerald Pelnar]

> From: Gerald Pelnar <wd0fyf at mpks.net>
> To: diy_efi at diy-efi.org
> Subject: Re: DIY_EFI Digest V5 #122
> Date: Monday, March 27, 2000 7:40 PM
> 
> 
> Bernd Felche wrote:
> 
> > To "cut my teeth" on uC practical applications, I'm
> designing a
> > uC-based system (fancy interior light delay with
acoustic
> warning)
> > with 5 inputs from switches and "12V" from various
> automotive
> > circuits. The uC is running at 5V.
> <snip>
> > So far, a simple voltage divider with forward signal
> diode, and
> > filter capacitor feeding into a (hex) Schmitt trigger
> (74C14) is how
> > far I've got. But the voltage can vary from about 8V to
> perhaps in
> > excess of 16V, but I want those levels to be "true"
> always. The
> > Schmitt will sense 3.5 to 5V as true when running at
5V.
> 
> Bernd--
> 
> To condition 12v inputs to your uP use a 74c901 or 74902
> instead
> of the 74c14. the 901 and 902 are buffers for 15V in to
5V
> out and
> operate from the 5V supply.

Oppsy. You might find the 4049 or 4050 buffers
easier to find.

Sorry,
Gerald Pelnar
wd0fyf at mpks.net
McPherson, KS
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