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Guide: plugpack selection

Discussion in 'Electronics & Electrics' started by LethalCorpse, Aug 18, 2008.

  1. whatdoesthisdo

    whatdoesthisdo Member

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    To give a bit more clarity, I am dipping my toes in with this project here.



    They are 5v addressable LED's and the Pi is 5v too. I want one (Australian brought) power supply to power both the pi and the leds form a standard wall socket, so it will need to be under 10amp.

    My original question, poorly worded I suppose, is the following understanding correct?
    You can use any amp power supplies without risk of destroying the pi or leds as they will only draw what they require? But you must get the correct voltage psu?
     
  2. merlin13

    merlin13 Member

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    Correct, providing the power supply is rated/capable of supplying as much current as the "Thing" it's feeding actually needs.

    Having a higher current rating on the PSU means you're not going to run out of Oomph if your "thing" wants more current.

    Think of this like a motor vehicle with, oh.. .a V8 engine in it. Tootle around town doing the shopping, the motor barely ticks over, with lots of spare grunt available. Hang a caravan behind it and it'll still run as well up the hills.

    Do the same with a small motor and it'll town-tootle fine, but load it down and it'll struggle. Or suddenly stop...


    BUUUUUT, I think you might be a tad confused here, because I am - I'm reading your term "...from a standard wall socket... under 10 amp..." in your last there as actually referring to the 10 amp limitation on the 2430/240 volt AC mains socket in the wall.

    If so then that involves a completely differing set of capabilities/requirements regarding The Care And Feeding Of Power Supplies. That's actually referring to the maximum power that the PSU itself and the entire connected setup can be allowed to be.

    10 maps max for the wall socket is the sort of power that a room heater uses, not anywhere near what a small Pi project needs. Unless your Pi is accidentally wired up to be a room heater... :D

    Also Correct.

    But just be aware there can be a clarifying (*cough* anal *cough*) Disclaimer on that. It's the actual final voltage/power source directly running your "Thing" that has to be the correct voltage.

    It can become confusing if/when you cascade power sources - having say... a 19 volt laptop supply to plug into the wall, then a step-down supply/board behind it to give you the 5 volts you need.

    In that instance you've actually got TWO PSUs there, combined to make ONE PSU that feeds the power to your device. Anal, like I said...
     
    whatdoesthisdo likes this.
  3. whatdoesthisdo

    whatdoesthisdo Member

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    Ok, good spot. Looks like I am getting confused with the input 240v 10amp with the output 5v 10amp. Thinking they are the same and the output cant go over 10amps.... but it can? Because it a much lower voltage?

    eg (getting this from the front page) 240v*10amp = 2400w but for the output 5v*10a=50w - A huge difference.

    Am I getting it or just embarrassing myself? lol
     
  4. merlin13

    merlin13 Member

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    You might need to go back over the hardware basics in that video, else I might inflict another Wall of Text on you. You're actually referring to both at 10 amps in the same context (ie maxiumum current rating), but both AC and DC at voltage levels where if you poke a finger in the wrong spot you'll either let the Angry Blue Genie out or find out how to die at 50 Hz.

    Basically if you want to follow the specs that he shows you'll need an Australian mains-rated plugpack that'd good for 5 volts DC at 10 amps output.

    No majors - you're getting there, and we all started at the beginning ourselves. ;)

    You just need to be a biiiit more specific about what you're looking at and asking, and isolate the Input power stuff from the Output power stuff.
     
  5. QuakeDude

    QuakeDude ooooh weeee ooooh

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    I'm going to put my hand up for help as well.. I'm way out of my depth, clearly I'm calculating something completely wrong. I need to buy a power supply to drive my LED Zigabee controller. The LED's are 2 rolls of 5m 24v strips. From what I can see the power consumption is (W/m):<12W, so worst case 120W. Allowing 20% brings it to 144W, but every calculator I can find converts 144W to just over 6 AMPS.. which seems like ALOT for two rolls of LED strip lights.

    1) is 6A actually right, and
    2) Can someone recommend one? I'm struggling to find anything thats over 5A in 24v.
     
  6. dakiller

    dakiller (Oscillating & Impeding)

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    Yes, it probably is about right. Led strips can use a lot of power when you get long runs.

    A plug pack that big is going to be hard to find. There would be options in the 19v range that do 180w used for gaming laptops, but you’re moving into open caged power supply territory here that you have to wire up yourself, not a nice plug pack.

    They do exist this big on eBay - https://www.ebay.com.au/itm/AC-240V...2349624.m46890.l6249&mkrid=705-154756-20017-0
     
  7. Franc

    Franc Member

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    Also you can find them on Aliexpress

    https://www.aliexpress.com/item/100...31-4&pdp_ext_f={"sku_id":"12000021834441170"}
     
  8. QuakeDude

    QuakeDude ooooh weeee ooooh

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    Holy shit. Okay. Thanks :(
     

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