Power supply - stronger ouput?

Discussion in 'General Electronics Chat' started by therock003, Jun 25, 2008.

  1. therock003

    Thread Starter Member

    Jun 25, 2008
    13
    0
    Hi,i just bought a sony device with a US power supply but I'm from Europe so i couldn't use it.I did go out and bought a step down transformer but i find it more convenient to plug in my sony psp power supply.

    Thing is,the device came with a power supply of 4.5v 500mA output,and my sony psp supply has an output of 5v 3000mA.

    Will i run into an problems if i keep using the sony psp supply on the device i just purchased?
     
  2. SgtWookie

    Expert

    Jul 17, 2007
    22,182
    1,728
    Well, the big concern is the voltage rating. Since your device requires 4.5v and you are feeding it 5v instead, you are giving it 111% of the supply voltage that the device is supposed to be receiving. Normally, you want to stay within 10% of the rating for maximum life expectancy.

    You could use a forward-biased Schottky diode in series with the supply to decrease the voltage. A 1N5817 or 1N5818 with a 500mA load on your 5v supply should get you just about 4.5v-4.6v to your load. Standard rectifier diodes such as 1N4001, etc. would drop too much voltage. I would not recommend trying to use a resistor to drop the voltage.
     
  3. therock003

    Thread Starter Member

    Jun 25, 2008
    13
    0
    11% is just 1% above the 10/5 of the maximum.And i dont even know if its the maximum.And i dont even know if 4.5 is the maximum.I'm just comparing the power supply in the box with another one i got.

    Wow I'm fairly new in this stuff,and this seems pretty hardcore to me.I'm having a pretty hard time comprehending this sentence,but i appreciate your involvement and i will do my best to take this seriously.

    So your suggesting 1N5817 or 1N5818 (whatever that is, cause I've got no ideas as far as diodes go) cause others would drop too much voltage and probably there wont be enough power coming out of my supply.

    BTW this is the message that i got from the guy i got the device.

    So based on that it looks like he things that the amp being 4 times higher is going to cause problems.

    For the time being I'm using a step down transformer to get the 220v input down to 110 since that's where the original supply goes,and output the 4.5v voltage to the device.
     
  4. Audioguru

    New Member

    Dec 20, 2007
    9,411
    896
    Did you measure 4.5V from the original power supply or is it unregulated and is 8V without a load?
    If it is not regulated then measure the output voltage of the PSP without a load to see if its voltage is higher than 5V. If it is higher than 5V then maybe its voltage will be much too high with the fairly low current for the device you are powering.
     
  5. therock003

    Thread Starter Member

    Jun 25, 2008
    13
    0
    I have not taken any measures,I've only read it on the outside sticker of the supplies.

    Here take a look.

    First its the original and then the psp supply.
     
  6. SgtWookie

    Expert

    Jul 17, 2007
    22,182
    1,728
    Why don't you simply ask Sony's technical support people?
     
  7. ricoban

    New Member

    Jun 23, 2008
    3
    0
    I have several power supplies from cell phones etc and they all go way over their rated DCV, like a 4.5 goes to 9V with no load.

    Based on your comment should I consider they are not regulated?

    So forgive me that I'm not that knowledgeable but why would a power supply be rated for 4.5 and put out 9V or is there a benchmark load that needs to be applied for non-regulated variety to get its rating.

    Am I even close in understanding this? :eek: Thanks!
     
  8. JoeJester

    AAC Fanatic!

    Apr 26, 2005
    3,373
    1,162
    Have you measured the two power supplys directly related to your question?

    What is the 4.5V 500 mA power supply's voltage with no load?

    What is the 5V 3000 mA power supply's voltage with no load?

    This link should shed some light on the why ...
     
  9. Norfindel

    Active Member

    Mar 6, 2008
    235
    9
    I recommend you to simply use the step-down transformer, it's the safest thing to do. If you can measure the output voltages, please do it, if the 5V supply gives less voltage **with no load** than the other supply in the same conditions, it should be pretty safe to use, IMHO.
     
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