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Dual power 5v & 12v for Raspberry and LCD controller

Comments

  • #2
    [Deleted User]
    Posts: 5,238 ✭✭✭ [Deleted User]


    12v house alarm battery + USB Outlet/ boost pack
    ATX PSU
    Server PSU.

    ..loadsa amps
    Best way to find out max. current is measure it at full load.


  • #3
    euser1984
    Registered Users, Registered Users 2 Posts: 1,977 ✭✭✭euser1984


    Out of curiosity I'm trying to light up an inverter here that takes 12v....none of the 12v psus I have seem to have enough current though.

    However, higher voltage ones do have enough current....if I use the higher voltage power supply will the inverter only pull the voltage it needs?


  • #4
    euser1984
    Registered Users, Registered Users 2 Posts: 1,977 ✭✭✭euser1984


    Out of curiosity I'm trying to light up an inverter here that takes 12v....none of the 12v psus I have seem to have enough current though.

    However, higher voltage ones do have enough current....if I use the higher voltage power supply will the inverter only pull the voltage it needs?


  • #5
    [Deleted User]
    Posts: 5,238 ✭✭✭ [Deleted User]


    What kind of inverter?
    You need more current not volts. You'll fry it if you go too far outside the voltage threshold. Usually 16v is over-voltage on a battery inverter.

    What PSU are you using. The inverter should only need mA when it's operating no load.


  • #6
    oscarBravo
    Technology & Internet Moderators Posts: 28,848 Mod ✭✭✭✭oscarBravo


    euser1984 wrote: »
    Hi,
    I have this for a picture frame project http://www.ebay.ie/itm/111743845103?_trksid=p2057872.m2749.l2649&ssPageName=STRK%3AMEBIDX%3AIT

    Above needs 12v but I can't figure out how many amps it needs??? Tech specs don't tell me http://img.ozdisan.com/ETicaret_Dosya%5C441291_5506225.pdf

    The raspberry pi needs 5v - would psu options are available to get all the power from one device....

    Thanks :)

    Current draw is going to depend on the panel. You'll need to connect a panel and measure the current draw.

    Digikey do a number of 5V/12V dual-output power supplies. This is the cheapest I can find.


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  • #7
    ozmo
    Registered Users, Registered Users 2 Posts: 3,899 ✭✭✭ozmo


    Could also use a PC power supply - possibly salvage one for free - the ones from the racks and Shuttle pcs (1U size) are very compact and you get a 5V and 12v at decent amps. adverts.ie might yield results.

    Or some of the older 3.5 Inch external harddisks sometime come with a high amp power brick that supply a 12V and 5V. XBox 360 psu has 12v +5v +3V3 so thats an option also.

    lots available in china cheap if you dont mind waiting 6 weeks:
    http://www.dx.com/s/12v+5v+dc+power+supply

    If you have an old satellite receiver box, old tv box etc - they are frequently thrown out - but inside there is often a separate switchmode 12V and 5V psu board - plus you get a nice case for your project for free. Same with the old original XBox- There is a 12v 5v PSU in there.
    (be careful with psu that are not in cases - modern psu normally use bleed resistors to discharge the caps when switched off - but still treat them with caution just in case it doesnt - charged capacitors can give nasty shocks & sparks)


    Also - Sometime things that require 12V or 9V - actually just drop the voltage down to 5V - sometimes with an inefficient 7805 circuit - 5V the max the chips are going run at anyway - if you are adventurous, it might be possible to bypass the devices voltage regulator and give it just the 5V it needs.

    “Roll it back”



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