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GCA173i infrared sensor board for use with GCA173 and GCA190 and various other options


By Peter Giling


Ifrared is maybe a good solution for sensing passing trains.
Only positioning these sensors is not always easy.
Specially when more than one of these sensors are close to one another,
they could influence each other.
And the fact that many cheaper infrred sensors are effected by (day) light, is a problem. In my program there is a system like GCA133 with four sensors, which have very low sensitivity to (sun)light.
Another disadvantage compared to the use of Hall sensors is the fact that it is never secure how long a pulse will last,
and the used sensor on this board, unlike Hallsensor, not easy for any form of counting.
But this TS471FE sensor is still a very reliable and simple solution, which can be used in combination with
GCA173, GCA190 and also direct to any of the GCA50/CAN-GC2/GCA_PI02 and/or WIO_xx is a serious possibility.

The use of any of these two boards makes it reasy to connect (and disconnect) 8 sensors to the mentioned GCA50 .. etc.
The advantage, compared to Hall sensor, is the fact that there is no need to fix magnets under the train.
The disadvantage when used without GCA173 is that a faster running train might trigger a pulse, too short to be noticed.
The whole unit consists of no more than three parts, a small printed circuit (28x8mm) and small connectors.
The use of these connectors is optional, wires can be soldered directly to pcb.
The heart forms a TS471FE sensor in combination with an infrared led.
The 940 nM IRled is directly connected to the TS471, without any resistor, and is sending a squarewave of ca 36 Khz
generated by TS471FE.
The direct or reflected signal, which is received by TS741 is recongnised as a valid signal and forces the output low.
Due to the infrared, the generated light beam is 100 % invisable.
Positioning this sensor leaves many options:

  • Between the sleepers,
  • In any building along the track (i.e.through a window)
  • integrated with signs or sign ports
  • etc.

More coming up…

gca173i-en.txt · Last modified: 2022/11/26 20:20 by phg