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Thread: 12v to 5V Power supply build?

  1. #1
    Constant Bitrate
    Join Date
    Feb 2008

    12v to 5V Power supply build?

    I have a laptop-based install. I have the DC-DC USB programmable power supply from powering/controlling everything. This device only has a 12V Auxiliary out and 19v out to the computer. I have a 7 port USB power supply that accepts a 5V external power supply, I definitely do need it because it won't charge my phone and operate a thumbdrive at the same time saddly.

    What's the best way to build/buy a 5v Power supply with enough amperage to power many devices. Through this hub I plant to run the GPS, OBD reader, female jack in the glovebox, two female jacks on the dash for misc stuff.

    Thanks for your support and help.


  2. #2
    Maximum Bitrate bratnetwork's Avatar
    Join Date
    Oct 2007
    Haledon, NJ
    A 7-port USB hub running full output on every port usually consumes about 3.5-3.7 amp (obviously at 5 volts). Now that is IF EVERY ports is being used at maximum capacity.

    You could buy a 5-volt POL PSU, most of which put out 15watts (3 amps) which for most cases is plenty of power for a 7-port hub.

  3. #3
    Join Date
    Jan 2008
    Dartmouth, MA
    Watch out with the carnetix. It needs a heatsink. At 2 amps draw, it's at 110 degrees fahrenheit. At 3, it pushes 140. These are linear regulators so the heat is to be expected with such a voltage drop.

    I just ordered the 50 watt switching regulator from here to replace it:
    But they also sell 25 watt switching regulators for cheaper than mp3car's linear regulators.
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  4. #4
    Raw Wave
    Join Date
    Nov 2009
    There are times I like simple linear converters - like the 7805 or LM317K etc - with a booster 2N3055 etc. Small, no noise, cheap, etc.
    But there's its 40W of heat at 14.5V supply and 4A output....

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