Bits and Pieces - GTi MacMini

From tunertricks.com March 25, 2005. Well, most of the major hurdles facing this project from the outset and the ways that I overcame them have been detailed in the tech posts I have written thus far and have published over the last couple of weeks. Although there were really a seemingly endless number of hours spent modifying, fabricating and wiring to finish this project (or at least finish it to the point you’ve seen here), I’ve tried to just cover the most challenging ones - rather than go into minute detail on every single aspect of the integration. By the way, I’ve really been enjoying answering the questions (and listening to the advice of) the many people emailing me directly about the more intricate details and hope that this will continue. Hopefully nobody will hesitate to ask about any part of this install that they have more questions about…That being said, I wanted to post a kind of wrap-up that goes into a little detail on a few more aspects of the GTi MacMini install that I thought were interesting. I’ll be posting on any upgrades and/or changes that I make to the system (which are already being planned), as well as on all the stuff I normally throw on here - iPod docks, show vehicle builds, big customer jobs, new products, etc - so please keep an eye on the site, as much more is still yet to come!

One of the most challenging things about this whole project was getting all of the equipment and peripherals that are required to make this work into such a small cabin. I’ve already talked about the space constraints concerning the monitor and the MacMini itself, but I would now like to introduce everybody to my rear passenger and driver’s side panels. This is where some of the larger components found a home once all the remaining space in the dash, the console, the roof, the trunk and under the hood was occupied by other components. One major piece of gear that needed to be located as far from the MacMini as possible for noise concerns was the Monster Cable power inverter and Apple AC/DC power supply for the computer.

At the time, I really wanted to power the computer directly with DC from the car, but, after testing the output of the Apple power supply, I realized that this would not be easy to do, as the MacMini requires a stable, regulated 18 volts of input to operate correctly. In discussing this aspect of the system with a few outside sources after the fact, I have decided that I will eventually make this change once I have located a well-built and stable DC to DC power supply that will take varying input voltage and output a consistent 18 volts DC. Anyone with a product they’d like me to check out, please feel free to email me and let me know what is out there. I’m doing my research, but more information is always better! In the meantime, here’s what I did in the current setup, and I will most likely keep the inverter in the vehicle regardless of how I end up powering the computer, as I like having the 110AC outlet for charging cameras and computers on the fly.

In car audio in general, one of the major problems has always been noise. Equipment manufacturers combat this is many different ways - filters, coils, inductors, remote location of power supplies - but it is ultimately up to the installer to make sure that power leads and signal leads remain as far from each other as is possible in the tight confines of an automotive interior. This was essentially the reason for locating the power supply component of the MacMini in the driver’s side panel of the car (in the back seat area).

The trickiest part of this was extending the original output cable that connects the Mac to its power brick, which was pitifully short when compared with the length I was going to need. Inside this cable, If you were to cut one open, you would find two 14-gauge(ish) wires that are the positive and negative DC outputs from the power supply to the computer, a small grey wire that I assume helps the power supply maintain the power requirements of the MacMini (anyone with a more detailed insight on this wire can let me know if I’m off base) and a shield for the cable. I extended all four conductors using Monster Cable twisted pair 14-gauge primary wire soldered in between the cut ends of the original Apple Cable and heat-shrinked for a solid and nice-looking connection on both ends. Overall I added about twelve feet to the length of this cable, and there have been no perceptible ill effects, even when voltage is measured with a Fluke multimeter. I also had to extend the power supply wiring for the Belkin 7-port powered USB hub that many of the peripherals are connected through. This was much more simple, as the AC adapter for the hub was a simple two-wire 5 volt DC setup, and it was extended in the same fashion using 12-gauge Monster primary wire.

Since the Monster Cable inverter only has two AC outlets and I had two devices as well as a 110 outlet to install, I also modified an extension cord (thanks for the assistance, Anthony) by cutting it and soldering it back together to act as a splitter for the secondary outlet on the inverter. Basically, the MacMini is plugged directly into the inverter, while a second cable is plugged into the inverter that has a female end for the Belkin AC adapter to plug into and a raw end that was connected to the terminals on the 110 outlet that is mounted in the rear side panel of the car (photos of this outlet are in the first MacMini post).

The inverter, Belkin and Apple power supplies were securely mounted to the rear speaker plate and the hard foam that fits between this plate and the rear quarter panel of the car after much modification to the foam to allow room for the components that were added. You can see in the photos below the wire maintenance and mounting required to make everything fit and function properly.

The inverter is turned on every time the ignition of the car is activated, and turns off when the car turns off. This seems simple enough, but several modifications were required to make the inverter stay on in different circumstances where the computer needs to remain on - or needs time to shut down - while I’m not in the car with the ignition key. For instance, when I pull in to fuel up, there’s no need to shut the computer down and then restart it simpy because I will be out of the car. But, I obviously couldn’t leave the car running while I gas up. So, I came up with a pretty neat integrated solution: My car has a small dome light behind each of the sunvisors for the front seat passengers. These lights are only activated when the visor is down and the sliding door that covers the mirror is open. So, I disconnected the light on my side (I never used it anyway) and wired the inverter’s turn-on lead through a relay that is activated by the visor switch. So, when I pull in to refuel, I simply lower the visor and open the mirror slide, then turn the car off, but the computer keeps receiving power from the inverter in this state. When I return to the car, I start it up and flip up the visor, returning the inverter to its normal state. This could have been accomplished with a traditional switch, but I felt that any aftermarket switch mounted somewhere accesible to the driver would look out of place, and I have already used up all the switch blanks in my car (one with the MacMini power button and one with an extra VW defroster switch that actiavtes my radar detector and laser shifter).

Secondly, there is the occasion when I pull into my destination (work is a good example) and don’t want to wait for the computer to shut down before I can leave the car. For this situation, I installed an Apex’i turbo timer that (when you leave the handbrake up before turning the key off and removing it) keeps the car running for a programmable amount of time. While the car is running on the turbo timer, I can get out with the key and arm the factory alarm while letting the MacMini run through its scripts and shut down properly before power is removed.

The opposite side panel on the passenger side of the car became home to the brain for the Alpine PXA-H701 processor that handles all the time correction, equalization and signal distribution for the audio system, in addition to allowing for driver control of the volume level, preset memories and subwoofer level through a simple rotary encoder and display mounted overhead (photos of the overhead controller can also be found in the original MacMini post). It was mounted in a similar fashion to the components on the driver’s side of the car. This effectively maximizes the distance between power componentry and audio componentry, and the result is absolutely no noise in the system.

One more item I wanted to post photos of is the simple circuit board I put together for the four blue l.e.d.s that illuminate the clear acrylic area around the iPod dock in the center console. I have previously illuminated these by mounting the l.e.d.s directly into the back edge of the iPod plate I fabricate and then soldering all the components and wiring on to make the l.e.d.s function. This time - mainly for serviceability - I decided to mount the resistors, l.e.d.s and wiring to a locally purchased project board that then screws onto the back of the iPod plate. If anything ever goes wrong with the lighting, I can simply remove this board and replace any faulty components easily without having to remove any adhesives or insulation materials that I have used in previous cases. Any illuminated iPod docking plates I build in the future will have this feature, which worked out really well…

Well, that’s about it for today. I hope these details are informative and (somewhat) entertaining to projecteers or the gadget intoxicated out there, and like I mentioned above, please don’t hesitate to email me with any questions and ideas you may have. It sometimes takes me a few days to get to all the emails - as there are quite a few - but I will answer, and I really appreciate the feedback. Keep checking for new developments and thanks again to everybody for their support of this site and this project!

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