Passive filter cleans up power-line communications
Are carbon filters less effective when the water contains more chlorine?
Modifying a Canon 350d/Rebel XT by removing its infrared filter
Replacing the Canon 350D’s Internal IR-Block Filter with Clear Glass.
Removal of Canon Digital Rebel (300D) IR Cut Filter for Astrophotography and Infrared Imaging
Choosing and Installing Mains Filters
Low-Sensitivity, Lowpass Filter Design
Spice subcircuit simulates any second-order filter