Two IR sensor sets with one detector

How to use two infrared sensor pairs to double the detection area of an Azatrax model train detector.

two across-the-track sensors When used in across-the-track configuration, Azatrax train detector circuits can be wired to two infrared sensor pairs. The detector will be 'on' when a train blocks either of the two infrared light beams.

Using two sensor pairs in this way will reduce the sensitivity of the detector. This normally does not cause a problem as long as the separation between each IR LED and its receiver is less than 12 inches (30 cm) and the IR receiver is shaded from the room lighting.

Extra sensor sets are available with wire leads that are 2 feet (60 cm) or 6 feet (180 cm) in length. Leads are 24-gauge twisted pair, similar to telephone wire. You may extend the leads up to 26 feet (8 m) by adding similar twisted wire.

IR sensor installation tips

For across-the-track mode, the two IR LEDs are wired in series to the detector circuit, and the two IR receivers are wired in series.

Order extra sensor sets. One set includes one IR LED and one IR receiver.
Does not include a detector circuit.

For reflective mode, the two IrLEDs are wired in parallel to the detector circuit. The two IR receivers are also wired in parallel.

It is possible to connect two IR sensor sets to one detector circuit in reflective mode, but results are not guaranteed. Why?

Sensitivity is significantly reduced because each IR LED only receives half the power from the detector circuit.
The uncovered IR receiver is exposed to room lighting. This may saturate the receiver's circuit on the detector module, preventing it from seeing the signal from the IR LEDs.
For best results, use fluorescent or LED lamps for overhead room lighting.

How to connect your own infrared sensors to an Azatrax detector circuit

For those who wish to use our detector circuits with infrared sensors other than the sensors supplied by Azatrax, order the detector circuit and choose the 'barefoot' (no sensors) option.

The 'white' wire is the IR LED anode (+)
The 'orange' wire is the IR LED cathode (-)
The 'yellow' wire is the IR phototransistor collector (+)
The 'green' wire is the IR phototransistor emitter (-)

Equivalent connections for alternate infrared sensors