An inexpensive millimeter-accuracy electronic length measuring board

A design is presented for a cost-effective, easy to use, millimeter resolution electronic fish measuring board. The device is easily assembled from commercially available electronic components and a customized electronic control board. The principal component of this design is a magnetostrictive linear distance sensor. This sensor is an alternative to previous approaches in magnetic measuring technology that used magnetoresistive or Hall-effect sensors. The measuring device is connected to a personal computer or personal digital assistant running a data acquisition application. Length measurements are taken by momentarily placing a magnet on the length board sensor at the desired measurement location. The described electronic fish measuring board is a robust, inexpensive and efficient alternative to other methods and devices used to rapidly collect relatively large numbers of high-resolution length measurements.