Ultrasonic range finder srf05 devantech srf05 the srf05 is a new design of ultrasonic range finder and features an extended detection range two operational modes are available single pin for trig echo or 2 pin for compatibility with the srf04 br br the input trigger is a 10 micro s min ttl level pulse and the echo pulse is a positive ttl level signal with the width proportional to the object range devantech srf05 ultrasonic range finder