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gca08-en [2018/11/12 08:56] (current)
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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 railraod table, we need all kind of DC power supplies.\\
 +Bying adapters is one option, nowadays also many of them are high effiency, 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. \\
 +In everage the effiency will be more than 80%.\\
 + 
 +There are two units available: ​
 +  * GCA08-1 1 Amp ouput, 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 (regulatir gets too hot) the regulator will stop.\\
 +Output voltage can be like 3,3 / 5  / 6  / 9 / 10 /12 / 15 / 18 / 24.\\
 +This is the cheapest way.\\
 +If you use a Traco-Power TSR 1-xxxx regulator, no cooling is need, and the full 1 Amp can be used.\\\\
 +No external settings are needed, since this very efficient chip is available in most common fixed voltages.\\
 +The maximum output is 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 Teaco_Power chip is better than 90% which makes cooling totally unneeded.\\
 +\\
 +
 +===== 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 selction 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 outpur max, or 3 Amp, depening 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 tranformer]] below\\
 +
 +^  Selection table for various voltages and current. ​ ^^^^^^\\
 +
 +^  Outout (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.^^^^^^
 +
 +
 +^  Outout (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.\\
 +Pometers 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 unnessacery,​ because little mistakes can couse insuries 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 sshould 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 ? =====
 +Basicly the transformer should have the following parameters:​\\
 +Secundary 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.\\
 +
 +
  
gca08-en.txt · Last modified: 2018/11/12 08:56 (external edit)