I created a scale speedometer that uses two IR sensors between the rails, and when a train travels over the sensor. the IR light is reflected back to the integrated photosensor. This starts a timer. When the train crosses the second sensor, the timer is stopped, and the distance vs time multipied by the scale reads out the scale speed on a 7 segment display, conveiently monted through the side of a scal shipping container on the layout. It’s a big hit with visitors, and helps us calibrate our dcc engines.
