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Tablet, why use DC to DC psu?

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  • Tablet, why use DC to DC psu?

    So i've done a complete camry 2007 pc build, i have one of those mammoth dc to dc converters. It seems clear to me why you would need one for a full fledged pc. I've moved to a tablet install and i want to know what would the the purpose of purchasing one of those little DC to DC converters i see so many people doing similar installs buying. Why not just hardwire a standard micro usb car charger with an ad a fuse, what am i missing?

  • #2
    Quality is what you are missing SNO


    • #3
      SNO? Quality in what sense? I understand that there may be room for improvement on methods of portable device charging (ie some fancy dc to dc converter), but i would think that the intended car charging method (factory car charger) would be extremely effecient, and of solid quality no?


      • #4
        Most of the car adapter type chargers are usually a reg and a couple of caps and most are of cheap components for cost. A specifically designed power supply designed for the specific use protecting against spikes/noise/low voltage/filtering and using much higher quality components. Don't get me wrong my first 3 car pc's were powered by multiple ripped open car adapter type power supplies of varying voltages to meet my needs. But on the same note I found using those were causing alot of little issues in my setups. Just my 2 cents and my opinions only. Good luck SNO


        • #5
          I choose the DC-DC for it's noise filtering as well as extra features like ignition turn on, and timer shutdown to make sure the PC shuts off gracefully. They are only $60-70 as compared to a $15 cigarette lighter type device that don't have the smart features.

          I do understand people are trying to do things on a budget, but I myself got scared after reading about this guy (The Stig) forum moderator on the Camaro5 forum who after finishing modifying is Camaro, had a fire that the insurance company did not want to honor:


          • #6
            But Stig's fire could be due to anything. AFAIK no cause has yet been identified, and I haven't seen his build threads.
            If it's electrical, I hope it isn't for the usual reasons - some of which I have mentioned (eg - the dude with the long alternator to battery/fusebox cable so that he could add a fuse; non fusing; overpopulated battery posts; AGM battery thermal runaway; cig socket fires; etc).
            But to not have a fire extinguiisher? But I've usually had one in every vehicle I've owned - and the most I've paid for a car in that past few decades is $1,000.

            As to bossman's OP, I'd tend to agree for tablets etc. Thou modern regulators are cheap, they are cheap to produce. They don't need the heatsinking that linear regulators need, nor the massive coils or caps that older SMPS types had. The most laborious and expensive part is the coil itself, but they are around the same volume as an old 7805 or LM317 (TO-220) regulator and SMD types.
            If they don't have crowbar or added protection, that could be added assuming the tablet does not have its own fuse.

            The biggest risk IMO is the usual warning about hot cig sockets. Even tho they can be rated up to 15A, many can get warm with only a few Amps (eg, 3A - equivalent to ~30W output, etc). But cig socket thermal fuses fix that, or hardwiring, or Merit/Euro sockets etc.

            Only if the tablet could take advantage of intelligent dc-dc converter signalling would I consider their expense - eg, shutdown imminent or warning etc.
            But tablets etc usually use the dc supply to charge the battery and run as opposed to PCs that have no battery after the dc-dc converter.

            However the experiences of those above means a lot. But if the technology has changed or improved... (I have never noted any noise issues from any of my cig socket converters, and prone devices include typical AM/FM/USB HUs, portable radios & audio gear, walkie talkies, mobile phones, etc. (However GSM phones can still be an issue with their tumor-causing peak energies!)
            Last edited by OldSpark; 11-28-2013, 01:49 AM.