The Circuitron 5204 DT - 4 Rolling Stock Detector (Part # 800 - 5204) is perfect for detecting hidden trains or rolling stock. It has four independent detection units on one circuit board. You can use them separately or together to control external devices. It comes with four Opto - Sensors that are installed between the rails to sense movement. When a train passes over a sensor, it activates connected DC accessories like indicator lights on a control panel. Each Opto - Sensor has independent sensitivity controls for adjusting to different lighting. Built on a 3 x 3' printed circuit board, it requires 10 - 18V DC. It's independent of track power and compatible with radio or carrier control systems.

Using this rolling stock detector is easy. First, install the four Opto - Sensors between the rails where you want to detect train movement. Connect the detector to a 10 - 18V DC power source, but remember it's independent of track power. You can then connect DC accessories like indicator lights to the detector. Adjust the sensitivity of each Opto - Sensor according to the lighting conditions around your tracks. As for maintenance, keep the detector and sensors clean from dust and debris. Check the connections regularly to make sure they're secure. When not in use, store it in a dry place. Also, since it's compatible with radio or carrier control systems, you can integrate it with other devices as needed.