Infrared Train Detection
Infrared train detection has the following advantages:
- The units detect all rolling stock in a train. This is particularly useful when trains may run in reverse.
- The infrared detectors are inconspicuous and are usually fitted with the circuit board under the baseboard.
- They are simple to install and can be fitted to existing track.
- No modifications are necessary to the track wiring or the rolling stock.
- They are electrically separate from the track. This makes wiring simple.
- They work in both light and dark.
- The detectors are suitable for Z, N, HO, OO and O gauge.
The units work by reflecting an invisible "infrared" beam off the underside of the trains. The infrared emitter and detector fit between the sleepers of the track.The emitter and detector are attached to an electronic circuit board that fits beneath the baseboard.This board filters out background infrared and electrical noise, and amplifies the detectors electrical signal.
All materials reflect infrared light in varying amounts.Rollingstock of any colour, constructed of plastic, metal or card is detected.As the infrared beam is emitted in a cone, its intensity falls off with distance. This allows the detectors to work inside tunnels.Matt black paint on the tunnel ceiling reduces the infrared reflected from it allowing the units to operate inside tunnels with only two or more inches of headroom. Alternatively a thin piece of foam may be fitted to the tunnel ceiling "foam is a very poor infrared reflector".
The IRDOT units consist of a printed circuit board measuring 30mm by 88mm. Electronic components are fitted on one side. The infra red emitter and decoder fit on the other side. They extend 22mm above the board and are 3mm diameter + thiuckness of the rubber sleeving.