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P1900 alternative power supply for Mac Mini

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  • P1900 alternative power supply for Mac Mini

    Hi,
    I am thinking of using notebook car power adaptor to power Mac Mini. So far, I found a notebook car power adaptor that can be adjusted to output 19v max 90W. Since Mac Mini required 18.5v, I think 19v should be fine.

    Mac Mini power brick is rated 110W, but from what I read on the web, it seems like Mac Mini is not drawing 110w even at maximum load. Do you think the 90W will be sufficient for Core Duo 1.66?

    My plan is to cut the connector from the power brick, and then connect to the notebook car adaptor with molex connector. From what I gathered, it should work by connecting the hot and ground together, and also connect the isense wire to ground through 3.3K resistor. Is there anything else I need to watch out when doing this?

    Someone here http://www.blisstonia.com/eolson/not...tonmacmini.php had tried to use notebook car adaptor to power the mac mini, and it worked. I also have the Kensington 120w, but I need it for my VAIO. The 90W car adaptor cost only USD 40, comparing to over USD 100 of the Kensington. So if the 90W car adaptor works, it will be a very cost effective option.

  • #2
    Usually those bricks are OVERrated, so 90W should be ok especially since you will not be using the cpu at 100%, unless you like to compile stuff while you drive . Although the best way to test it is to go to RadioShack and get one of those current metters and meassure just exaclty how much current were talking about here, but my hunch is that 90W should be ok, since I have desktop PCs at home that draw less.

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    • #3
      Originally posted by johnsin View Post
      Mac Mini power brick is rated 110W, but from what I read on the web, it seems like Mac Mini is not drawing 110w even at maximum load. Do you think the 90W will be sufficient for Core Duo 1.66?
      Yes. The brick has some reserve for FireWire and USB devices, you won't probably be burning DVDs in your car too often etc.


      should work by connecting the hot and ground together, and also connect the isense wire to ground through 3.3K resistor. Is there anything else I need to watch out when doing this?
      Not sure about Intel mini. I used 6k6 to be sure for my PPC one.
      Some of these laptop power supplies tend to suck quite a lot of power even in idle mode.

      I would still go with P1900 - it requires less power when in stand-by mode, gives you one or two extra outputs (+5V and +12V in my case) plus many other features (battery protection, startup/shutdown control etc.).

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      • #4
        I tend to think the 90W should be OK. Anyway, I will test the car adaptor and post if it does a good job. Thanks.

        Comment


        • #5
          Does the iSense wire require 13 volts on the Intel boxes, like the PPC, or will it work with 19?
          Originally posted by ghettocruzer
          I was gung ho on building a PC [until] just recently. However, between my new phone having internet and GPS and all...and this kit...Im starting to have trouble justfiying it haha.
          Want to:
          -Find out about the new iBug iPad install?
          -Find out about carPC's in just 5 minutes? View the Car PC 101 video

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          • #6
            As far as I know, the isense only required connection to ground through 3.3K resistor. Please correct me if I am wrong, thanks.

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            • #7
              Just a quick update for all of you, the notebook auto adaptor with 3.3K resistor mod works well with my Intel Mac Mini. However, I still have no idea what the 3.3K resistor is for, maybe anyone with the knowledge could explain to us how the 3.3K resistor work with the grond connected. Thanks.

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              • #8
                I have just done the same thing. I used the Kensington 72 Watt Universal Adapter.

                I was able to determine that 72 Watts was more than enough because I have a Kill a Watt tester which plugs into the wall and then I can plug the Mini's power supply into it and it tells me the current and power draw.

                I have the Core Duo 1.6 GHz and the power draw was never more than 22 Watts. It only hit 22 Watts while 3 USB devices were plugged in and it was playing a DVD. It idles at 16 Watts. So 72 Watts is definitely more than enough.

                It amazes me that such a powerful machine can run on only 22 Watts.

                I have no idea what the control wire is for, but I used a 2K ohm resistor and it did the trick.

                I really wanted to use the Carnetix P1900 for it's startup/shutdown controller and to power my Lilliput, however I've been waiting for the P1900 for months. No distributor has it in stock and I'm sick of waiting.

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                • #9
                  MikesSwelch,
                  Nice to hear it works for you as well. I was going to use Carnetix P1900, but I also had encounter the same problem with you.

                  I usually put MacMini to sleep before I stop the engine. When the power to car adaptor is cut, MacMini automatically goes into deepsleep/safesleep/hibernate. With 'restart on power failure' enabled under the energy setting, it does wakeup the MacMini from deepsleep when car is ignited. The best part is MacMini is completely power up from deepsleep in just less than 10 seconds.

                  My biggest problem is sometimes the power to car adaptor is cut due to cranking problem during ignition. I am trying to get a time delay relay to delay power to car adaptor say 5 to 10 secs. It should do the trick to solve my cranking problem. Is your Kensington survived the cranking?

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                  • #10
                    P1900 is supposed to come out out to the shelfs 11/15 at least that's what the posts on their message boards say.

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                    • #11
                      I don't understand why you guys are having trouble finding the P1900, i know over here in the uk they are sitting on the shelves and work extremely well....

                      Thought about going the way you described but just couldn;t do without the start up / shutdown and the secondary power source for the screen...

                      Glad it works for you though... It is definately a cheaper option if you don't need the extras...
                      CLICK ME

                      Smart Car due for completion beginning of march....

                      Log with pictures to go online shortly after.

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                      • #12
                        Originally posted by johnsin View Post
                        Is your Kensington survived the cranking?
                        It is not the problem of the Kensington surviving the cranking. The problem is where you are getting your power from. Right now the Kensington is plugged into the cigarette lighter. The cigarette lighter's power is cut during cranking. It is designed this way so that you aren't draining so much power that your starter isn't getting enough.

                        In order to "survive" cranking, I would need to run power directly from the battery to the Kensington. This would cause the unit to never power down. A single pull/single throw relay would easily solve this problem. I will most likely be implementing this method.

                        I currently have an Opus 150 DC-DC power supply and I am trying to use this to power the Kensington.
                        The reasons for this are:
                        1. I trust the Opus to give 12V where I'm not so sure I trust the Kensington to give 18V if it's receiving a range of Voltages.
                        2. I want to use the startup/shutdown controller built into the Opus. However, I'm having trouble with this and will probably not deal with it much longer.

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                        • #13
                          MikesSwelch,

                          "A single pull/single throw relay would easily solve this problem. I will most likely be implementing this method."

                          Could you share the details on how to implement this if we wire the adaptor to battery directly? Thanks.

                          Comment


                          • #14
                            Originally posted by MikesSWelch View Post
                            In order to "survive" cranking, I would need to run power directly from the battery to the Kensington. This would cause the unit to never power down. A single pull/single throw relay would easily solve this problem. I will most likely be implementing this method.
                            1. Kensington or iGo often do not survive cranking, especially if the battery is not 100% or in winter. They are designed to power laptops, so (unlike P1900) they are not designed with cranking in mind. Laptop's battery is expected to handle the short voltage drop. I was using a dedicated battery taht was disconnected from the rest of the car during the cranking.

                            2. Kensington or iGo adapters draw much more power than P1900 when in standby mode. I do not remember exactly, but I believe the curent exceeded 150mA.

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                            • #15
                              Originally posted by www.workingcars View Post
                              I don't understand why you guys are having trouble finding the P1900, i know over here in the uk they are sitting on the shelves and work extremely well....
                              I'm still waiting on mine. None of the stores selling it in USA have it in stock, and I really don't feel like paying to have it shipped from UK, plus pay who knows what other import fees or what not.

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