DIY_EFI Digest V5 #122

[Gerald Pelnar]

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.

Gerald Pelnar
wd0fyf at mpks.net
McPherson, KS
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