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Thread: Power Supply? We don't Need No Stinking Power Supplies!!!!!

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    FLAC chut's Avatar
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    Power Supply? We don't Need No Stinking Power Supplies!!!!!

    I am prolly going to get flamed out of existence for this one but here goes.....

    If my laptop needs 12 VDC to run and the power adapter I have converts 120 VAC to 12 VDC, Why do I need a 12VDC to 12VDC power supply to run it? Why can't I just directly wire the laptop to a 12VDC source in the car? When I use the cheap little power inverter I have, I get a terrible buzzing noise. When I plug the adapter into the wall and plug the laptop into the car stereo via IP bus, it sounds pretty good. Eventually I will buy a USB sound card for the laptop so it will sound better but for now it's pretty groovy.

    Any Takers?

    Peter

  2. #2
    Variable Bitrate MeanGT's Avatar
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    You most likely would be able to directly wire your laptop to your 12v car system. The only foreseeable problem would be caused if your laptop is very sensitive to voltage changes, because a cars electrical voltage varies from around 11v to 14v,, I think most electronics are safe in that range however. Also, make sure you get your positive and ground right!!

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    Maximum Bitrate MikeHunt79's Avatar
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    My laptop asks for +15v in, but works fine when wired sirectly to my cars electrical system, even when cranking!

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    Maximum Bitrate osirisdon's Avatar
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    Re: Power Supply? We don't Need No Stinking Power Supplies!!!!!

    Originally posted by chut
    I am prolly going to get flamed out of existence for this one but here goes.....

    If my laptop needs 12 VDC to run and the power adapter I have converts 120 VAC to 12 VDC, Why do I need a 12VDC to 12VDC power supply to run it? Why can't I just directly wire the laptop to a 12VDC source in the car? When I use the cheap little power inverter I have, I get a terrible buzzing noise. When I plug the adapter into the wall and plug the laptop into the car stereo via IP bus, it sounds pretty good. Eventually I will buy a USB sound card for the laptop so it will sound better but for now it's pretty groovy.

    Any Takers?

    Peter
    Nah you wont get flamed, give it a shot see what happens. If it works good for you. If it dont well then good for you again.


  5. #5
    I'm sorry, and you are....? frodobaggins's Avatar
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    Originally posted by MikeHunt79
    My laptop asks for +15v in, but works fine when wired sirectly to my cars electrical system, even when cranking!
    then you are a lucky mf
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  6. #6
    jol
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    FLAC jol's Avatar
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    The car's system is rated 12v, but it ranges between 10.5 and 14, if not more.

    Most electronic gear is rated 12v, at about +-5%!
    thats why.

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    FLAC cproaudio's Avatar
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    I love experiments like that. Why not, just plug it in. One time at band camp, I wired 4 Dewalt 18volt batteries fully charged in series to a pair of Boston 4X6 unfused. The batteries were about 20 volts each fully charged. The 4X6 had about 80-82 volts DC going to them. It lasted 3 seconds before shorting out the voice coil. Since I didnt fuse the batteries, the terminals started smoking. I mean big huge puff of white smoke. While I was screaming "ohh **** ohh ****" my coworkers just stood there and laugh their asses off. here I am trying to save over $300 worth of batteries. I got burned when I grabbed the wires to disconnect the battery terminals. Now I know Dewalt 18V batteries can melt 18AWG wires if they're shorted out. I managed to pop a 80 amp fuse with a Dewalt 18V battery. That was fun. BTW 82 volts can shock you just as bad as the AC in the wall.

    Anyway back to the subject. The reason why we use regulated PSU for laptops and DC-DC PSU made for miniITX boards is because computers are low voltage and very sensitive to electricity. Thats why computer components come in anti static bags with a **** load of warning stickers about static electricity. Im sure you know how static electricity works and what cause it. It's basically a micro sized lightning. PC components are sepicified to use a certain voltage. It has a tolarance range. As long as you're in that range you're OK. If you ever take a multimeter and measure a AC style ATX PSU, It doesnt produce a true 12 V. it'll be something like 12.1, 11.9 volts or something like that. The computer components well tolerate that. If your laptop can tolerate the voltage of an unregulated car battery then you shouldnt have any problem. I would say that a car with healthy battery and alternator will have a voltage of 10 -15 volts. If you happen to drive a car with bad battery and alternator, the voltage could range from 7 volts (bad battery during crank) to 22 volts (bad regulator in the alternator). Are you willing to feed 58%-183% of DC voltage to your laptop? Will your laptop tolerate that range? If you dont know don't try it. Or you can send it to me and I'll try for you. One other thing too is that people use regulated DC PSU is cuz some times PC will reboot during crank. Even if the battery voltage dip below the inverter's minimum voltage for a few milliseconds, it could cause the PC to reboot. Thats what people want to avoid and why people use regulated PSU.
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    FLAC cproaudio's Avatar
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    dude we're not gonna search for you man. do your own damn search. Im sure you didnt stumble on to this forum today. You probably been following this forum for a while and have probably read few posts about DC-DC ATX PSU
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    I just stumble onto this today

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