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2 x regulators for double current?

Discussion in 'General Electronics Discussion' started by qweets, Oct 18, 2010.

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  1. qweets

    qweets

    48
    0
    Sep 26, 2010
    hello everyone : )

    i have an old PSU for a HP printer that can output approx 18v @1.1amps
    (which i believe is 19.8 watt)

    My circuit however needs aprox 10v @1.5amps ( 15 watt)

    I have two 10v regulators that offer 10v @ 1amp

    So I wonder, can I use these 2 x regulators together in parallel with my PSU to provide my circuit with enough current?


    thanks for any help. : )
     
  2. Resqueline

    Resqueline

    2,848
    2
    Jul 31, 2009
    The regulators themselves might be parallelled to get the required current, but here the PSU is the limiting factor with its 1.1A capacity.
    Only by using a switchmode regulator off the PSU can you keep the wattage and get the neccessary higher current. It also needs to have a higher than 75% efficiency.
     
  3. qweets

    qweets

    48
    0
    Sep 26, 2010
    thanks for your reply : )

    the regulators are "Linear voltage regulator,BA17810T 10V 1A" , i do not think they are switching type.?

    i also have a PSU from an old PC ...i think it may be around 300watt with 12v

    but i've just read the 10v regs need 12.5v minimum too work. ....typical. : /

    hmm..not sure what to do now? I might look on ebay for a higher current psu? As i cant see a switching type regulator that will fit my bread & vero boards. not sure how that would work?
     
  4. qweets

    qweets

    48
    0
    Sep 26, 2010
    i just found a regulator that can output 2amps , so hopefully i'll be o.k with that and the 18v 1.1amp psu. fingers crossed. : )

    thanks for your help. : P
     
  5. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

    25,418
    2,788
    Jan 21, 2010
    You understand that unless it's a switchmode regulator that 2 amps out requires 2 amps in (actually a little more).
     
  6. qweets

    qweets

    48
    0
    Sep 26, 2010
    hi : )

    i did not need the full 2amps, but yes i think i need to just buy a new ac/dc adaptor with a higher amp output.

    I was told that I can up the amps in a step down conversion under certain situations.
    So seems i need to disregard that in this instance.: /

    thanks for your help : )
     
  7. davenn

    davenn Moderator

    13,672
    1,891
    Sep 5, 2009
    yes but the original PSU transformer still has to be able to supply the current you want
    and the indication is that it cant.

    D
     
  8. qweets

    qweets

    48
    0
    Sep 26, 2010
    thanks.: )

    i just noticed a 10v 20 amp psu for sale. i wonder, would this have a standard 13 amp fuse in the plug? or a special fuse to provide the 20amps?
     
    Last edited: Oct 19, 2010
  9. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

    25,418
    2,788
    Jan 21, 2010
    I assume you're in the UK :)

    That would have a mains fuse rated at around 2A as a guess.

    I have no idea if/how the power supply might limit the output current.
     
  10. qweets

    qweets

    48
    0
    Sep 26, 2010
    yep, uk : )

    So that would be 240v 2a converted to 10v 20a

    Stepped down voltage, but the amps raised,

    This is why i thought a 18v 1.1a psu might go to 10v 1.5a .

    not to worry i have a psu that i may buy, should do the trick.

    peace: )
     
  11. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

    25,418
    2,788
    Jan 21, 2010
    The power supply you are talking about is either switchmode or has a transformer. Both devices can reduce voltage and increase current.

    You are talking about a linear regulator which reduces the voltage but the current remains constant.

    That's one reason why we use transformers to reduce the voltage before using a linear regulator to regulate the output voltage.
     
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