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gca94-en [2018/11/12 08:56]
gca94-en [2018/11/12 08:56] (current)
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 +====== GCA94 8 Input power efficient current detector, also suitable for high current G and 1 Track. ======
 +[[english|{{ ​ rocrail-logo-35.png}}]]
 +[[:​english|Content]] -> [[:​hardware-en|Hardware]] -> [[:​hardware-en#​interfaces|GCA]]
 +  *  [[mgv-overview-en|The GCA modules]] ​
 + \\
 +^^^^By Richard Andrews, Helmut Schäfer and Peter Giling ^^^^
 +===== Description =====
 +The current detector [[http://​​doku.php?​id=mgv93-en|GCA93]] is a reliable way to creatie feed-back in your layout.\\
 +But many railroaders experience the 1,2 Volt loss of power as not appreciable.\\
 +And also, the current is limited to the maximum load of the bridge rectifiers on the input side of GCA93.\\
 +That will basicly disable the use of GCA93 with G-track or 1-track railroaders.\\
 +So we created a better solution.\\
 +Richard Andrews had this same thought and has been experimenting with different options by using a current tranformer more or less directly connected to A/D converter.\\
 +In that way, without any form of amplification,​ it is hard to reach the minimal 2,6 Volt, you need to activate an input suitable to be used straight to digital systems.\\
 +It was fearly easy to add an amplificator to it, but that also increased the sensitivity to distorsions.\\
 +In Germany, ​ Helmut Schäfer created a different approach, using two transistors of which the first one is in normal conducting state.\\
 +This eliminates the sensitivity to distorsion, as always produced by running trains.\\
 +[[http://​]] sells this board in two or four ports.\\
 +This superb design of Helmut Schäfer is permitted to be used for the GCA94.\\
 +GCA94 is made to accept 8 inputs, and can be used like GCA93, straight to GCA50, CAN-GC2 or GCA_PI02\\
 +No measureable power loss is the result, and there is no need to protect each input with a PTC Fuse, like on GCA93.\\
 +The unit is functional compatible with GCA93, also each input has its own indicator led.\\
 +One of the two wires to the rails is feeded through any of the coils, which will mostly be sufficient for any locomotive or illuminated waggons\\
 +For more sensitivity,​ a second or third loop through the coil is possible, which could be necessary when you like to detect also\\
 +10K resistors, mounted between the two wheels of a waggon.\\
 +One other way to increase the sensitifity is to feed both rail wires through the coil, **but in opposite directions**.\\
 +===== The board, professionally made. =====
 +|  {{:​gca:​gca94_pict03.png?​700}} ​ |
 +|  though parts are reasonably small, ​ \\  it is still a rather simpel unit for do it yourself. ​ \\  In the GCA-kits these resistors are all 125 mW small metal film types. ​ |
 +===== The hardware =====
 +|  {{:​gca:​gca94_sch.pdf|The schematics}} ​ |
 +|  {{:​gca:​gca94_pcb.pdf|Printed circuit with parts positions}} ​ |
 +|  {{:​gca:​gca94_partslist.pdf|The list of parts}} ​ |
gca94-en.txt · Last modified: 2018/11/12 08:56 (external edit)