> is it possible to demodulate a 38khz signal to get data using discretes
and
> logics?


Yes.
But it is very unlikely to be worthwhile unless you mainly value the
learning experience or have an extremely demanding requirement (and even
then it may not be).

For about $US2 retail you can buy a 3 chip device that has an optical filter
(piece of coloured plastic), amplifier, bandpass filter  and
detector/demodulator plus associated gain control circuitry. To reproduce
this yourself with equal results would take a handful of transistors or
several op-amps and associated components in each case. The size would be
much larger and achieving performance similar to the $2 part would not be
trivial.


        Russell McMahon

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