In message <610ad388.34b69691@aol.com>, PHXSYS writes >ello > >I need a very accurate linear position sensor, that can measure verticle >object travel of approx 1.5 inches. Cost is an issue. It will be an input for >a PIC16F84, so a digital signal would be less work. You haven't specified the accuracy you need! How about an arrangement using a rotary encoder with a gear/ratchet assembly? Or, adapt the technique used in digital calipers. I think that they use some type of low-cost capacitive sensor. Moire' fringing is an optical technique sometimes used for this type of application. Leon -- Leon Heller: leon@lfheller.demon.co.uk http://www.lfheller.demon.co.uk Amateur Radio Callsign G1HSM Tel: +44 (0) 118 947 1424 See http://www.lfheller.demon.co.uk/dds.htm for details of my AD9850 DDS system - schematic and software.