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Thread: DIY DC>DC adapters? 19v, 12v, and 5v

  1. #1
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    Join Date
    Dec 2006

    Arrow DIY DC>DC adapters? 19v, 12v, and 5v

    I'm just starting research on what is hopefully going to be the coolest thing i've ever done for a car so far- and in-dash gps system. (okay, so i havnt done much for cars...)

    I've got a laptop with a halfway decent cpu and 512 ram, with a 1 gig CF card crammed in as a hard drive- and no screen. Long story short, thats what i want to use as a system. Screen is still undecided, as well as the rest of the hardware... but something that occured to me is i dont have a clue as to how i'm going to power this equipment.

    I'd like to run a hard drive- just one, for starters. a 3.5", for storage purposes. That means i'll need a clean 5v and 12v source- something my car cant output. The laptop takes a 19v (3.5A max) input- something else i'd need.
    While the laptop has a battery (and therefore can handle some time without power for the car to start) the hard drive can not- and i'd like to be able to manually power this machine on when the car is off, and then start the car without inturupting my process. This means i'll need a battery system, seperate from the cars electrical system.

    Now i'm sure there are plenty of systems out there that will do this, and i'm sure people will reccomend them and praise them- But what i'd really like to do is the following:

    (edit) this paragraph was removed when i found out i could replace it with 'build a tank circuit' (/edit)

    I still need the following, however:
    1) a way to get a 19v, ~3A power source from the tank
    2) a way to get a 12v ~1A power source from the tank (shouldnt be an issue on a 12V tank, if it stays clean)
    3) a way to get a 5V ~.5A power source from the tank

    All three need to be clean- no spikes, drops, line noise, etc- cant afford to blow this stuff up. I'll also need to power a touchscreen, but i'm assuming most of them can handle 12v.

    stipulations: If at all possible i'd like to avoid the 'throw in an inverter, an APC battery backup, and a few power brick adapters for all your happy devices!' answer- its bulky, its un-clean, and the whole idea kind of bothers me- DC>AC>DC... wheres the fun?

    explanations, links, tips, ideas, etc- i'm all ear-err, eyes.


    after a few minutes in the IRC room, I learned a few things that i diddnt see in the FAQ- i guess i should go back in there.

    The battery backup is called a tank. The autoswitching i'm looking for is called a tank circuit.

    So to sum that up, I'm going to need to build a tank circuit, and put a mail cutoff on iether side of it- one to cut off power to the tank when the car is starting, and one to cut off power to the devices running off the tank 30-45 seconds after the car is off (unless the bypass switch is thrown)

    I then still need to get clean, regulated 12 and 5v signals, and a clean 19v one. Most of the adapters available for this sort of thing run in the $80+ range- i'd like to avoid those... and build my own (if its significantly cheaper)- I've got the tools, and know how to use them... just not the know-how. A big for-instance- Assuming i use a 12v tank- even with a cutoff from the car, is that 12v clean enough to run sensitive equipment? probably not... how would i regulate it?

  2. #2
    Low Bitrate
    Join Date
    Dec 2006

    nudge nudge

    sorry about the noob question, i edited it to replace as much noob with newb as possible!

  3. #3
    MySQL Error MatrixPC's Avatar
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    Sep 2003
    Beach City, Socal
    There is a DIY for 12V and 5V but not 19V.
    Search the forum for "12 and 5V POI anyone?" under my name.

    Edit: here is the link 5V and 12V POL anyone?
    2004 Matrix XR A7N8X-VM/400 AMD XP-M 2500+, DS-ATX
    89 Supra Turbo P3 600E@750/Abit BE6 II, Alpine M-BUS Car2PC.
    Y2K Accord Dell GX150
    RoadRunner is the best FE PERIOD
    EmoRebellion is a SCAMMER

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