Environment-proof, self-contained proximity sensor enclosed in a rugged stainless steel housing, designed to meet the requirements of aerospace, ordnance, marine, mass transit and high performance industrial equipment. Operation by the Eddy Current Killed Oscillator (ECKO) principle, which is used to detect metal objects passing in front of the sensing face. Once a target metal is detected, a trigger signal is produced which is then passed through the output conditioning circuitry to give a high or low output, depending on the sensor application.