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+====== GCA190  Infra red reflector gate for mounting between sleepers. ======
+[[english|{{  rocrail-logo-35.png}}]]
+[[:english|Content]] -> [[:hardware-en|Hardware]] -> [[:hardware-en#interfaces|GCA]]
+ \\
+^^^^By Peter Giling ^^^^
+===== Description =====
+In the modeltrain world we have various different ways of generating contacts, so called feed-back.\\
+They are absolutely indispensable in automatic control.\\
+In general, I mention here 8  different ways, but there are more, mostly more expensive:\\
+  *  1.  Railcontact, where the train makes a short circuit between the rails. Very common with everything from Göppingen,\\
+  *  2.  Current detection, a system where a part of the track is isolated and any current drawn from that isolated section generates a contact. GCA offers GCA93 and/or GCA94  for it.\\
+  *  3.  MFX and Railcom and Lissy, sending back their decoder address, but the exact location has to be added separately.\\
+  *  4.  Reedcontacts and hall sensors, needing a magnet under your riding material. GCA  offers the GCA173 (GCA179) for that option.\\
+  *  5.  GCA173 can also be used together with GCA173i, to use it as reflection Infra-rad sensors.
+  *  6.  GCA173, with adapted firmware, can als be used with GCA173 wheel-counter. Rocrail is also adapted to this.
+  *  7.  Infra red gates or reflectors. GCA has the GCA133 and GCA141(LocoNet) in program to achieve that
+  *  8.  RFID, a system where a transponder is fixed to the rolling stock.
+  *  9.  Many other, ususally more expensive, systems.
+  *  10.  GCA190,  IR detection for feed-back of your trains always seemed to be either hard, or complicated.
+It is rather easy to install, and no cutting in the tracks is needed.
+The used sensor is a TCRT5000, and is not sensitive for normal (day)light.
+Consider this:  A TL lamp straight above sensor on a distance of 1,5 m is too much light.\\
+In those cases, fit the sensor with an angle so the light does not radiate in directly.\\
+The way the systems works is not suitable for wheel (-magnet) counting because it reacts on almost anything that approaches within 15 mm distance\\
+To get a very good signal, some black plastic wagons might need a bit of white paint on the bottom,\\
+but anything metal will be detected 100%, even the axes of the wheels.\\
+The benefit of this unit is a reliable and simple way of installation.\\
+The unit comes as a set with 8 sensor boards and an connection/indication board, with the standard  \\
+interface connection, which adapts GCA50(0)(a)(LocoNet), CAN-GC2(CBUS), RocNet (Raspberry Pi) and WIO.\\
+It also can be used for connection with S88 modules, but then 5V should be added for supply.  Ask [[peter.giling@rocrail.net|Peter]].\\
+With all 8 sensors connected, the board needs 65 mA at 5V supply.\\
+When sensors are 'active', the current will increase by 4 mA for each sensor.\\
+The sensor itself fits nicely on the solder-side but can be connected with wires to it, if needed.\\
+TCRT5000 sensor is also available as a type with longer wires (TCRT5000L).\\
+The size of it is 5,5x10mm, and could be mounted sideways along a track, where it will react on passing wheels, or fits between the sleepers.\\
+The first look into the technical description showed that the sensor needs quite some current :  60 mA.\\
+That was not acceptable, since an octal set of these sensors like this GCA190, would draw almost 0.5Amp !!\\
+The TCRT5000 could easily be used without any pc-board, but because of this power consumption, a board was \\
+indispensable with the extra Fet Transistor and two resistors.\\
+That made it possible to reduce the power consumption dramatically.\\
+All together, the board remains small, and will fit nicely under the track.\\
+\\
+===== How it looks like =====
+|   {{:gca:gca190_pict_02.png}}  |
+|  the sensor board with sensor fixed (left hand side)  \\  and the connection/indicator board, with a led for each sensor   \\   At the right hand side a complete pcb-set of 1 connector board and 8 sensor boards   \\  Boards are pre-cut so they are vary easy to separate.  |
+\\
+===== How to fix the sensor board. =====
+The idea for this sensor came from the wish to use it for tramway and Faller-car system.\\
+In tramway situation, cutting rails, after finishing the scenery, is difficult, because of the way rails are fixed in the tarmac.\\
+Now, if a sensor is 'misplaced', it is very easy easy to make a hole somewhere else and put the sensor there.\\
+The sensor board could be fixed under the bottom of the baseboard with little screws, but an easier way is using hot glue.\\
+Fixing is easy and also removing , when ever necessary, is also quite simple.\\
+The same remarks count for using the sensor in Faller-car system.\\
+\\
+=====Different options=====
+)The sensors as used in the GCA190 board are working fine when the sensor is not exposed to much light.\\
+There is also an option for a different sensor board, which can also be used in normal lighted area.\\
+This sensor is mounted on a small board , GCA173i, which has an Infrared transiever on board and a separate IR led.\\
+The led can be placedd opposite the transceiver ( where a train runs through the beam and braks the Infrared light beam.\\
+Put the led along the transceiver and you will have a signal when the Infrared beam is reflected.\\
+)There is also a small board GCA94-s available which will be published in short time.\\
+This unit is 1/8 of the GCA94, which is sensing currents that can be as low as coming from an N-track train, to any large scale, like G or 1,\\
+and also provides a 100% isolation with anything, achieved by the use of a current transformer coil.
+===== The hardware =====
+|  {{:gca:gca190_sch.pdf|Schematic drawing}}  |
+|  {{:gca:gca190_pcb.pdf|Pc-board and parts positions}}  |
+|  {{:gca:gca190_parts.pdf|Bill of materials}}  |
+\\