MOTM

If you invert the output and sum it with the uninverted input signal, 
you'll get highpass. You could do it with an external mixer with 
reversible phase on the inputs, or build that in on a daughterboard. 
What would it take, a switch, an opamp, and 3 resistors?

Moe

--- In motm@egroups.com, "Tkacs, Ken" <ken.tkacs@j...> wrote:
> 
> Is it possible to make a few modifications to an MOTM-440 Lowpass 
Filter to
> make it a highpass? Not that I would take a Dremel to my own, but 
I'm just
> wondering if a few changes to the layout and front panel legend 
might yield
> a whole new module. A 24 db/oct highpass filter would be useful.
> 
> I had a thought today while shovelling snow that a CCD "bucket 
brigade"
> device is similar with electricity to styrofoam or fiberglass 
insulation is
> with thermal energy. They both have little 'cells' that slow down 
the
> transmission of their respective energy types.
> 
> Back to our regularly scheduled program.