Auto noise filters typically consist of a couple capacitors and inductors. = =A0They are available off-the-shelf, typically for audio applications or yo= u can reverse engineer one or design your own. =20 --=20 http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist .