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Might I trouble you a moment with my power supply, good sirs?

Discussion in 'Power Electronics' started by Pharaday, Nov 21, 2019.

  1. Pharaday

    Pharaday

    69
    2
    Jan 18, 2016
    Hello, gents and gentleman! How are ya today?! 20191121_091253.jpg 20191121_090054.jpg I found this obsolete power supply. It's small and kind of nice and I really want to use it for its multi voltages. It's a Cosel R50A-3. I found the user's manual and a few other PDFs on it but I can't for the life of me figure out how to get any voltages besides 3 volts.

    If you look on the pictures it has only one set of outputs for positive and negative. I read in that PDF that it has multiple voltages from 3 volts up to 24 volts. None of those PDFs on it tell you how to change the voltages. It says that it's internally switching, which I guess means that it's internally switching. that Can you guys help me figure out how to switch to the other voltage settings, please? I don't think anything is broken with it it turns on like normal and the LED indicates that it's on. I just can't get it to change its voltage. Please help!
     
    Last edited: Nov 21, 2019
  2. Harald Kapp

    Harald Kapp Moderator Moderator

    9,413
    1,924
    Nov 17, 2011
    As per the manual:
    upload_2019-11-21_17-38-20.png
    • The R50A has only one output.
    • Output voltage is adjusted by a potentiometer. This potentiometer is next to the LED
    • upload_2019-11-21_17-40-57.png

    Of course it means that. This is a switch mode power supply as opposed to a linear power supply.
     
    Last edited: Nov 22, 2019
  3. Pharaday

    Pharaday

    69
    2
    Jan 18, 2016
    lol I aaaaalmost included this paragraph in my initial post:

    You may notice that potentiometer there. According to the fine print of the user's manual, that potentiometer is 4 adjustments of two to three volts around the voltage setting you're on. In other words, it's set to 3 volts. I have tested it and it's true the potentiometer will take me down to about one volt or up to about 5. It's not for the entire voltage output range of that power supply. I promise I do all my preliminary research before I come to you guys
     
  4. Pharaday

    Pharaday

    69
    2
    Jan 18, 2016
    And I mean, it's an easy mistake to make and I thought that at first as well. There's probably no way I would have ever known that's what the sentence meant in the manual had I not been able to test it myself
     
  5. Alec_t

    Alec_t

    2,702
    715
    Jul 7, 2015
    Perhaps your supply was designed as a 'universal' one which needed only one or two component changes to customise it for a specific voltage?
    If you check the voltage rating of the big electrolytic output capacitors it may indicate what maximum voltage you could expect.
     
  6. Pharaday

    Pharaday

    69
    2
    Jan 18, 2016
    25V, 820 tiny farads

    Also, the the user manual says it has 3V, 5V, 12V, 15V and 24V with the in between values obtainable through the range adjustment potentiometer. There has GOT to be a way to get those other voltages. But since it says it has "embeded switch", maybe that means that whatever equipment this was a power supply for had the ability to switch the voltage somehow. I don't think this power supply was for a computer.
     
  7. Pharaday

    Pharaday

    69
    2
    Jan 18, 2016
    Upon Googling embedded switch, I see that it has to do with daisy chaining multiple components together and being switched by the end component or something like that it was highly technical. I'd say maybe it can only do 3 volts except that the user manual for that one power supply tells me otherwise
     
  8. Pharaday

    Pharaday

    69
    2
    Jan 18, 2016
    But let's do a reality check here. Would it be logical to make a whole power supply that just does 3 volts? That seems pointless in my admittedly narrow View. Why not just get an AC adapter
     
  9. Hunter64

    Hunter64

    10
    5
    Nov 20, 2018
    You've got a single output 3V 30W power supply. The output voltage can be adjusted between 2.85-3.6V.

    That's it.
     
    narkeleptk likes this.
  10. Pharaday

    Pharaday

    69
    2
    Jan 18, 2016
    Guys I wanna thank you for your help.

    For my sanity I'm gonna say I'm misinterpreting the manual and there is only 3 volts OR I'd need a daisy chain of these things to "embedded" switch it and I only have a daisy link.

    But yall are tops. Thank you for the benifet of your knowledge.
     
  11. Alec_t

    Alec_t

    2,702
    715
    Jul 7, 2015
    Can you post a link to the user manual?
     
  12. 73's de Edd

    73's de Edd

    2,744
    1,133
    Aug 21, 2015
    Greetings Kinde Sire Pharaday . . . . . . ( Where's your Chage ? or Phshield ? )

    TRUE . . . . . what you have found yourself is being the FIRST unit, of the series shown below.
    One unit, itself, will not adjust between ALL of those voltage ranges being offered by the series..
    upload_2019-11-24_2-9-6.png

    It has its switch mode supply portion, feeding into the the primary of a SELECTED power transformer.
    There is being in excess of 50 watts power going into that primary. Then, in accordance to which of the series you want, they install the appropriate 1 of 7 power transformers for the voltage /current unit that you need. Also, voltage CORRECT, filtering capacitance and and appropriate power rectifier diodes.

    The 24 V unit will have the most SECONDARY turns and use the lightest gauge of wire.
    For the other transformers, a popular manufacturing procedure is to then use a variant in same gauge wire choice by making an ersatz high current Litz wire by taking the 24 V length of wire used and then folding it in half and use that pair, being bi filar wound . . . side by side . . . to make a 12 V secondary winding.
    That could also be done by taking the 24V winding wire length and folding it yet again to get two pairs . . .four wire lengths to be used side by side to get 6V.
    Each time, the fewer turns, gave the desired lower voltage output, and with the available current doubling.
    OF course . . . . initial prototype design experimentation would establish the CORRECT turn count for those different transformers secondaries voltages .

    SO you won't be using that unit for anything but that ~ 3 VDC and 10A output.

    EXAMINING . . . .

    Your first photo . . . . . being in the fore ground is the LC05003T power transformer and its FET driver is at the left rear, being clamped to the units case for heatsinking. Now can't you fully relate to the transformers "50" and " 3 " apects of numerical assignments ?
    Being at the right central foreground is a dual power Schottky diode package to get DC to your filter inductor and the medium sized two BLUE caps in the right mid chassis. See if they are not being of a 12VDC or skimpier 6VDC voltage rating ?

    What were you daydreaming of that unit being used for ?

    Somehow, I feel that you had visions of sugar-plums dancing in your head and being resplendently supplemented with side mouth drool.

    Remember that unit is only designed with a power transformer core mass, capable of ~ 50 watts .
    If you were fixated on some HEAVEE 12VDC use. This unit is putting out ONLY a wee bit more than 4 amps.

    Wonder what that unit, once was supplying 3V-10A to ?

    Thaaaaasssssssit . .. . .

    73's de Edd

    If you are with me and I break wind, you'll be the second one to know . . . .



    .
     
    Last edited: Nov 24, 2019
    Martaine2005 likes this.
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