Results 1 to 9 of 9

Thread: 12v to 5v 5A Power Supply

  1. #1
    Newbie
    Join Date
    May 2008
    Posts
    2

    12v to 5v 5A Power Supply

    Hello guys,

    I looked a lot of projects, but this is the best, because with this, we can
    provide clean 5v power with 5A.

    I just made the Circuit Board, and mounted in my Honda Jazz to
    supply 3 USB hubs.

    The heart of this project is the LM338k Regulator, with a BIG Heatsink,
    this will get hot quickly... :-)

    After you place all in board, u just need to adjust the resistor, to get
    the 5v in output.

    C1 1 14000uF or 10000uf 40 VDC Electrolytic Capacitor
    C2 1 100uF 50Vdc Electrolytic Capacitor
    C3 1 0.1uF Disc Capacitor
    C4 1 0.01uF Disc Capacitor
    R1 1 5K Pot
    R2 1 240 Ohm 1/4 W Resistor
    U1 1 LM338K 1.2 to 30 Volt 5 Amp Regulator

    This is the link for the original project...
    ( I removed everything before the C1, because we have 12v DC)

    http://www.aaroncake.net/Circuits/supply.asp
    Attached Images Attached Images

  2. #2
    Low Bitrate Beehphy's Avatar
    Join Date
    Apr 2007
    Posts
    85
    The LM338 is a linear regulator. About 60% of the power in a 12 to 5 volt linear regulator gets burnt up as heat. To deliver 50W to the load 65W is burnt as heat.

    Also, this design doesn't have a disable. It never turns off. Unless you have a relay controlling power to the circuit, your battery is toast! Running off your car's battery without the eingine running would drain it really quickly.

    I linear regulator is very stable and free of power line noise, but it is just not worth the waste.

    If you need BIG power to run your USB system, and want to do it with style and grace just follow the link in my sig. 5V@10A, 93% efficient, USB Sync'd, 300 kHz switch freq, and professionaly built.

    |
    |
    \/

  3. #3
    Raw Wave Rob Withey's Avatar
    Join Date
    Apr 2000
    Location
    Bedfordshire, UK
    Posts
    2,139
    Old Systems retired due to new car
    New system at design/prototype stage on BeagleBoard.

  4. #4
    Fusion Brain Creator 2k1Toaster's Avatar
    Join Date
    Mar 2006
    Location
    Colorado, but Canadian!
    Posts
    10,052
    Quote Originally Posted by Rob Withey View Post

    Ooh, I like that chip... And 85%+ efficient for high current 5v out. Never even knew it existed. Good find!
    Fusion Brain Version 6 Released!
    1.9in x 2.9in -- 47mm x 73mm
    30 Digital Outputs -- Directly drive a relay
    15 Analogue Inputs -- Read sensors like temperature, light, distance, acceleration, and more
    Buy now in the MP3Car.com Store

  5. #5
    Low Bitrate Beehphy's Avatar
    Join Date
    Apr 2007
    Posts
    85
    Quote Originally Posted by Rob Withey View Post
    $36.60 on digikey.com (Link)

    Still needs a little work to become an installable piece, but this will let people with minimal electronics knowlege create a 5V switcher PS for their carpc's in an afternoon.

  6. #6
    Newbie
    Join Date
    Oct 2008
    Posts
    12

    lm7805

    Another voltage regulator you could use is the lm7805. Its cheap and if voltage between 5-20V is applied the output voltage is a constant 5V.

  7. #7
    Fusion Brain Creator 2k1Toaster's Avatar
    Join Date
    Mar 2006
    Location
    Colorado, but Canadian!
    Posts
    10,052
    Quote Originally Posted by Kishon View Post
    Another voltage regulator you could use is the lm7805. Its cheap and if voltage between 5-20V is applied the output voltage is a constant 5V.
    Maximum power draw is less than the maximum draw on a standard USB hub, and definately less than 5A.

    Also it is not very stable over vast ranges of temperature.

    I love and use them all the time, they even appear on the FB.
    Fusion Brain Version 6 Released!
    1.9in x 2.9in -- 47mm x 73mm
    30 Digital Outputs -- Directly drive a relay
    15 Analogue Inputs -- Read sensors like temperature, light, distance, acceleration, and more
    Buy now in the MP3Car.com Store

  8. #8
    Newbie
    Join Date
    Oct 2008
    Posts
    12

    7805c

    Point taken regarding the temp. I don't know which type you are using. I have installed one of these..(below). they seem to handle up to 1.5A and you can add a heatsink.

  9. #9
    Newbie
    Join Date
    Oct 2008
    Posts
    12

    7805c

    forgot the attachment.LOL
    Attached Images Attached Images  

Similar Threads

  1. Replies: 115
    Last Post: 03-05-2011, 03:54 AM
  2. Getting 5v AND 12v from POL DC-DC Smart Power Supply
    By XxAndyxX in forum General Hardware Discussion
    Replies: 4
    Last Post: 06-19-2007, 11:09 AM
  3. amd athlon 1.3 ghz-- where does it get it's power from, 12v or 5v?
    By scott_fx in forum General Hardware Discussion
    Replies: 6
    Last Post: 02-22-2006, 07:53 PM
  4. del
    By hanzacra in forum Classified Archive
    Replies: 1
    Last Post: 08-07-2005, 10:32 PM
  5. Inexpensive DC-DC power supply for 12V only?
    By P4_2.66GHz in forum Power Supplies
    Replies: 10
    Last Post: 11-20-2004, 09:17 PM

Bookmarks

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •