Infrared Light Train Detection

This page presents information on infrared - Across The Track train detection circuits. The circuits are designed around the LM339 comparator chip and can use a wide assortment of matched infrared - emitter / detector pairs.

The infrared "Across The Track" train detection circuits utilize the LM339 comparator, a quad comparator IC that operates from a single supply voltage. This allows for a versatile design that can be tailored for various applications in train detection systems. The primary function of these circuits is to detect the presence of a train by using infrared emitter and detector pairs, which are strategically positioned across a railway track.

In a typical configuration, an infrared LED (emitter) is placed on one side of the track, while a phototransistor (detector) is positioned directly opposite. When a train approaches, the infrared light emitted by the LED is interrupted, causing a change in the output of the phototransistor. This change is then fed into one of the inputs of the LM339 comparator.

The LM339 compares the voltage level from the phototransistor with a predefined reference voltage. If the signal from the phototransistor drops below the reference level due to the train obstructing the infrared beam, the output of the comparator switches state. This output can then be used to trigger further actions, such as activating warning signals, controlling track switches, or notifying a central monitoring system.

The design allows for flexibility in selecting the infrared emitter and detector pairs, enabling the use of components that best fit the specific detection range and environmental conditions. Additionally, the circuit can be further enhanced with features such as hysteresis to prevent false triggering from ambient light interference or noise.

Overall, these infrared train detection circuits provide a reliable and efficient solution for monitoring train movements, ensuring safety and enhancing operational efficiency in railway systems.This page presents information on infrared - `Across The Track` train detection circuits. The circuits are designed around the LM339 comparator chip and can use a wide assortment of matched infrared - emitter / detector pairs. 🔗 External reference