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+====== GCA08  High efficiency universal power supply for 1 or 3 Amp ======
+[[english|{{  rocrail-logo-35.png}}]]
+[[english|Content]] -> [[hardware-en|Hardware]] -> [[hardware-en#interfaces|GCA]]
+  *  [[mgv-overview-en|The GCA modules]]
+ \\
+^^^^By Peter Giling ^^^^
+===== Description =====
+On many places under the railroad table, we need all kind of DC power supplies.\\
+Buying adapters is one option, nowadays also many of them are high efficiency, meaning not evaporating a lot of energy into heat.\\
+Unfortunately many of these adaptors do not give what they promise.\\
+Furthermore, the very annoying thing about having these adaptors under your table is the fact that you also need 230V there.\\
+And exactly that, specially where infants like to help there parents with this nice hobby, is not much to encourage.\\
+The better option is to run a low 16V ac line under the table and use that.\\
+This power supply will give you that option and can be set-up in various ways and voltages, either adjustable or solid.\\
+For ac input, it needs at least the same voltage as the desired output.\\
+If you are running dc line under the table, it should be at least 2 Volts higher than output.\\
+Adjustable versions could be as low as 1,25 V, up to the maximum you put in.\\
+The switching regulator is very energy efficient. \\
+On average the efficiency will be more than 80%.\\
+There are two units available:
+  * GCA08-1 1 Amp output, size 40x22 mm
+  * GCA08-3 3 Amp output, size 40x62 mm
+===== The final results =====
+| {{:gca:gca08-3_pict_02.jpg?0x400}}  |  {{:gca:gca08-1_pict_02.jpg?0x400}}  |
+|  GCA08-3 the 3 Amp unit  |  GCA08-1 the 1 Amp unit  |
+|  For both units a professional board is available  ||
+\\
+\\
+===== GCA08-1,    1 Amp output=====
+{{  :gca:gca08-1_pict_02.jpg?150}}
+This simple supply can be used in different ways.\\
+If you install a standard LM78xx regulator, it can supply a full 1 Amp when the regulator is cooled sufficiently.\\
+Without cooling, it is very depending on the incoming voltage and the used current, how far you can.\\
+If it goes too far (regulater gets too hot) the regulator will stop.\\
+Output voltage can be between 3,3 and 24 volt\\
+This is the cheapest way.\\
+If you use a R-78Ex.x regulator, no cooling is required, and the full load is available.\\\\
+No external settings are needed, since this very efficient chip is option in most common fixed voltages.\\
+The maximum output is 0.5 or 1 Amp, input from transformer can be up to 20V ac or 24V dc.\\
+A total of 6 parts are located on this board.\\
+Efficiency with this power chip is better than 90% which makes cooling totally unnecessary.\\
+\\
+===== GCA08-3,  3 Amp output adjustable=====
+{{  :gca:gca08-3_pict_02.jpg?200}}
+This board is able to supply 3 Amp in a chosen voltage.\\
+Please refer to tables below for selection of the right output.\\
+\\
+\\
+\\
+\\
+===== Hardware =====
+|  {{:gca:gca08-1_sch.pdf|GCA08-1 schematics}}  |
+|  {{:gca:gca08-1_parts.pdf|GCA08-1 partslist}}  |
+|  {{:gca:gca08-3_sch.pdf|GCA08-3 schematics}}  |
+|  {{:gca:gca08-3-adjustable.pdf|GCA08-3 The parts list for adjustable 3 amp version }}  |
+^ N.B. Only complete ordered kits will be supported! ^
+\\
+===== Selecting the output. =====
+This board can be equipped in 1 Amp output max, or 3 Amp, depending on the chosen chip.\\
+Maximum input ratings for all configurations:\\
+dc 30 Volt\\
+ac 24 Volt\\
+For correct calculation of needed transformer, see [[http://wiki.rocrail.net/doku.php?id=gca08-en#which_transformer|which transformer]] below\\
+^  Selection table for various voltages and current.  ^^^^^^\\
+^  Output (V)  ^  VR1 for 1 Amp  ^  VR1 for 3 Amp  ^  R1  ^  R2  ^  P1  ^
+|  1,24  |  LM2575T-adj  |  LM2576T-adj  |  x  |  short*  |  no  |
+|  3,3  |  LM2575T-3,3  |  LM2576T-3,3  |  x  |  short*  |  no  |
+|  5  |  LM2575T-5  |  LM2576T-5  |  x  |  short*  |  no  |
+|  12  |  LM2575T-12  |  LM2576T-12  |  x  |  short*  |  no  |
+//**  *  *short means to insert a short bridge (piece of wire).
+**//
+^  Other voltages can be achieved by installing resistor R1 and a small adjust potmeter 20K.^^^^^^
+^  Output (V)  ^  VR1 for 1 Amp  ^  VR1 for 3 Amp  ^  R1  ^  R2  ^  P1  ^
+|  1,24-12 V  |  LM2575T-adj  |  LM2576T-adj  |  1 KΩ  |  no  |  20 KΩ  |
+\\
+With this setup output will be adjustable from 1,24 V to max 26 V depending on input voltage.\\
+\\
+Using a potmeter inserts the risk of output changing after a while.\\
+Potmeters are never stable on the long run.\\
+^  This table shows various , not adjustable voltages.  ^^^^^^
+^  Vout (V)  ^  VR1 for 1 Amp  ^  VR1 for 3 Amp  ^  R1  ^  R2  ^  P1  ^
+|  6  |  LM2575T-adj  |  LM2576T-adj  |  1 kΩ  |  3,9 kΩ*  |  no  |
+|  8  |  LM2575T-3,3  |  LM2576T-3,3  |  1 kΩ  |  5,6 kΩ  |  no  |
+|  9  |  LM2575T-3,3  |  LM2576T-3,3  |  1,8 kΩ  |  12 kΩ  |  no  |
+|  10  |  LM2575T-5  |  LM2576T-5  |  1,2 kΩ  |  8,6 kΩ  |  no  |
+|  16  |  LM2575T-12  |  LM2576T-12  |  1 kΩ  |  12 kΩ  |  no  |
+Vales in this table are a close approach.\\
+Far more exact values can be achieved by using 1% metal resistor from 96 series.\\
+Resistors are calculated by the following formula.\\
+^R2 = R1 x ( ( Vout/1,24) -1) Ω^
+|  N.B. Potmeter is not installed.  |
+===== Fuse F1 =====
+**ALWAYS INSTALL FUSE !!!!!!!!!!!**\\
+\\
+Do not think it will be unnecessary, because little mistakes can cause injuries or fire hazard.\\
+With PTC fuse assembled, you are always safe, and never have to worry about ever having to replace it.\\
+Also the fuse need to be adapted to the the desired output.\\
+In general the values for the multifuse should be:\\
+For 1 Amp out use 0,5 - 0,8 Amp fuse.\\
+For 3 Amp out use 1,5 - 1,85 Amp fuse.\\
+\\
+===== Which transformer ? =====
+Basically the transformer should have the following parameters:\\
+Secondary voltage :  minimal equal to output.\\
+Power (in VA) Minimal (V x A x 1.2), where :\\
+  *  V = Volt output \\
+  *  A = Ampere output.\\
+It is possible to use a DC power supply.\\
+The input voltage should be at least 3V higher than output.\\