Maximite-based ultrasonic rangefinder

摘要

This circuit for an ultrasonic range-finder is based on the Maximite Microcomputer (Silicon Chip, March-May 2011). Many of the additional parts were salvaged from an old ultrasonic burglar alarm kit but suitable equivalents should be available. With the parts shown, the minimum sensing range is around 30mm and the maximum around 4-5m.In brief, an ultrasonic transmitterproduces a burst of high-frequencysound waves (40kHz) which thenbounce off the nearest hard object intheir path and return to be picked upby the receiver unit. The delay betweentransmission and reception indicatesthe distance that the sound wavestravelled and thus the distance to thereflecting object.