[sdiy] Making a HPF using a LPF...??

[Jean-Pierre Desrochers]

HI list,
Maybe it's a dumb question but
I need to make some light on the following..
Can I make a High pass filter using a Low pass filter
and a summing amp using both positive and negative inputs?
Suppose the following:
A wave form passes thru a LPF, then we mix
the LPF output filtered wave (negative input)
with the LPF input unfiltered wave to the mixing amp
positive input.
Will the summing amp output be a HPF from
the incoming wave ?

JP