Results 1 to 6 of 6

Thread: Back on the forum + planning the next install

  1. #1
    Newbie
    Join Date
    Jul 2003
    Location
    Rochester NY
    Posts
    6

    Back on the forum + planning the next install

    Hey everyone. I was on this forum a *long* time ago while I was in college, kind of awesome that my account is still here. I've been lurking the past couple weeks reading threads and getting caught up to the current state of things, and I'm about to start putting together a pc for my current car, replacing the stock head unit completely.

    I've done several diy audio projects (headphone amps, dacs), played with arduino a bit, and write software for a living - which is why I can't stand to buy an off-the-shelf nav unit that doesn't do half the things I want it to do the way I want it to do them.

    I've got a bit of an oddball hardware list, but aside from the gps and fm stick it was all laying around:

    intel d945gclf atom 1.6ghz mini-itx board
    2gb ddr2-667
    128gb "apple" ssd (toshiba made, from 2009 macbook pro)
    usb 802.11n
    usb bluetooth
    bu-353 gps
    adstech usb fm tuner
    slim ide dvd (if it stays, its getting replaced with slot-load)
    usb pcm2702 "alien" dac (old head-fi.org DIY forum project)

    the system is currently hooked up at home to a monitor, mouse, and keyboard in a mini-itx case with a 80w dc-dc and a wallwart, I'd say on average its drawing about 30 watts AC under light load (music playback).

    the car itself has a couple small mods (sway bar upgrade, stiffer springs) but the helpful (and only cosmetic one) is the "shark fin" antenna - it covers the stock antenna opening on the roof and has enough room inside to fit the gps puck.

    What I need to get:

    • a monitor/touchscreen combo - I'm thinking about starting with this and replacing the resistive with capacitive touch
    • a shutdown controller - probably going to use arduino + relays
    • something to make a steady 12 volts from the messy car voltage swing
    • a 4-channel amp (probably a class D board) to take over from the head unit
    • a small (probably opamp based) preamp with physical volume control and a simple switch to get a line-in independent of the pc
    • an obd2 reader (may end up DIYing a small obd2-serial reader)
    • a couple connectors (MCX and motorola I think) to connect my stock antenna to the usb fm
    • some spare interior trim pieces to hack


    Installing the carpc:

    As for installing it, that is where things are going to get really tricky. Unlike my college days, throwing the pc under the seat and using a line-in adapter and hacked gamepad is not good enough for me. Its going to be a fun exercise in learning fabrication technique for me.

    • LCD bezel (probably will use ABS) that fits into (or possibly is molded into) the stock head unit opening; with the preamp's volume knob, line-in jack (3.5mm), and a usb port
    • homemade aluminum double din mini itx case (its going to be a squeeze but I should have the room)
    • hook up through factory radio harness (I might end up running a dedicated power and ground)
    • regulation of car 12v-ish to 6.5v-ish using something efficient, some smoothing caps, then separate LDO 5v linear regulators for the usb dac and the fm tuner to give them as clean power as I can get
    • something to cap off/weather seal the stock antenna opening while letting the usb cable and radio antenna through


    Software:

    Ah, the trickiest part. My first goals are audio playback (tag driven, like itunes), cd ripping, fm radio, gps navigation, bluetooth handsfree, and obd2 datalogging. Being able to dock an iDevice and play music from it would be neat, but not required. I think the only commercial software I need at the moment is gps navigation.

    For a frontend I'm leaning towards using openmobile at the moment. I'm going to look through the source code this weekend.

    Anyways, that ended up being a lot longer of an introductory post than I intended. I'll probably start up a worklog thread and move most of this info there. I'd love to hear feedback on my planned setup, and I look forward to jumping into a bunch of ongoing discussions on the forums!
    - Steve

  2. #2
    MySQL Error soundman98's Avatar
    Join Date
    Jan 2008
    Location
    on the border of northern IL/IN
    Posts
    5,848
    it really looks like you've got a pretty good handle on everything!!

    Quote Originally Posted by pddjsteve View Post
    the system is currently hooked up at home to a monitor, mouse, and keyboard in a mini-itx case with a 80w dc-dc and a wallwart, I'd say on average its drawing about 30 watts AC under light load (music playback).
    [*]something to make a steady 12 volts from the messy car voltage swing
    [*]a shutdown controller - probably going to use arduino + relays
    so i take it from ^those^ parts that you are using something like a pico-psu(requires regulated 12v input)?

    i understand using the aurduino for startup/shutdown(a little more options then most dc-dc's), but why not go with a m1/2/3 and get the option to not need to regulated the 12v line going into the psu?


    Quote Originally Posted by pddjsteve View Post
    [*]a small (probably opamp based) preamp with physical volume control and a simple switch to get a line-in independent of the pc
    i use the jl cl-rlc for this(full active setup, 4 total-- 3 for volume, 1 for sub level). imo, it is the best option compared to building one yourself..


    Quote Originally Posted by pddjsteve View Post
    [*]hook up through factory radio harness (I might end up running a dedicated power and ground)
    heavily recommended-- while some carpc setups might theoretically work on oem wiring, the amount of hassle it can create is usually not worth it..


    Quote Originally Posted by pddjsteve View Post
    [*]regulation of car 12v-ish to 6.5v-ish using something efficient, some smoothing caps, then separate LDO 5v linear regulators for the usb dac and the fm tuner to give them as clean power as I can get
    a couple months back, there was a adjustable buck/boost power adapter on ebay that would probably work really good for this-- i think it was something like $50 after shipping.

  3. #3
    Constant Bitrate kolton5543's Avatar
    Join Date
    Apr 2011
    Location
    Safford Arizona
    Posts
    170
    Alright! Something new. I'll be watching.

  4. #4
    Newbie
    Join Date
    Jul 2003
    Location
    Rochester NY
    Posts
    6
    Thanks for the feedback!

    Quote Originally Posted by soundman98 View Post
    so i take it from ^those^ parts that you are using something like a pico-psu(requires regulated 12v input)?
    The power supply came with the case, and came with a ac-dc switching power brick, it says 12-14v output on the sticker. I need to play with monitoring the DC voltage and amp draw in between the brick and the atx power supply to get a better handle on the requirements.

    Quote Originally Posted by soundman98 View Post
    i understand using the aurduino for startup/shutdown(a little more options then most dc-dc's), but why not go with a m1/2/3 and get the option to not need to regulated the 12v line going into the psu?
    and

    Quote Originally Posted by soundman98 View Post
    a couple months back, there was a adjustable buck/boost power adapter on ebay that would probably work really good for this-- i think it was something like $50 after shipping.
    I've been thinking about the M3, actually, if I have enough room to fit the motherboard and screen both in the dash I really have no need to use the power supply that came in the itx case - its actually larger than the pico units. I'd go arduino mainly because I have a couple other things I want to control (thump control on the amp, antenna amplifier are the two that come to mind right now). Its probably just another occurance of me wanting to DIY as much as possible, though.

    I think I saw the thread you're talking about, and there is a buck/boost thing I found on ebay. For that price though, I'm thinking I may be just as well off getting the M3.

    Aside from needing to learn decent plastic fabrication skills so my dash doesn't look sketchy, I think settling on a power supply is going to be my biggest issue.

    Quote Originally Posted by soundman98 View Post
    i use the jl cl-rlc for this(full active setup, 4 total-- 3 for volume, 1 for sub level). imo, it is the best option compared to building one yourself..
    Oh, thats a neat product. The balanced input is nice.

    My usb dac only has line-level output, so I could take that and feed it right to the amp, but then I'd need to rely on the pc volume control and I like having a physical volume knob. I also don't want to run any line-in signal through an ADC on the motherboard's audio, then back out through the DAC so I want at least the ability to switch 2 sources - it looks like the CL-RLC does that too. I mainly am thinking about building something over buying because its a hobby (addiction?). I can throw something together from my parts bin for the enticing cost of free :-) I'm trying to limit any diy audiophile insanity at the moment, but I'm thinking version 2 might get something inspired by this.

    Quote Originally Posted by soundman98 View Post
    heavily recommended-- while some carpc setups might theoretically work on oem wiring, the amount of hassle it can create is usually not worth it..
    The stock stereo is on the same fuse as the cig lighter, its rated for either 12A or 15A. I might be able to squeak by for pc, screen, and amp (I'm probably going to go for a high efficiency class-D and I don't ever listen to it very loud - more of a sound quality guy). I'll probably bench test my total power draw once I get all the components decided on and bought, then do the wiring. I probably will only end up using the ignition/accessory line and the antenna amp turn on wire, and run my own 12V and ground.
    - Steve

  5. #5
    MySQL Error soundman98's Avatar
    Join Date
    Jan 2008
    Location
    on the border of northern IL/IN
    Posts
    5,848
    Quote Originally Posted by pddjsteve View Post
    Oh, thats a neat product. The balanced input is nice.

    My usb dac only has line-level output, so I could take that and feed it right to the amp, but then I'd need to rely on the pc volume control and I like having a physical volume knob. I also don't want to run any line-in signal through an ADC on the motherboard's audio, then back out through the DAC so I want at least the ability to switch 2 sources - it looks like the CL-RLC does that too. I mainly am thinking about building something over buying because its a hobby (addiction?). I can throw something together from my parts bin for the enticing cost of free :-) I'm trying to limit any diy audiophile insanity at the moment, but I'm thinking version 2 might get something inspired by this.
    unfortunately, the rlc has 2 outputs and 1 input one passthrough output, one amplified output, and a single balanced input..

    that preamp looks like a pretty nice diy project-- powering it in-car is still going to be a issue-- it looks like the psu needs to output 15, 0, 15v. and i don'te really know of any auto-psu's that do that.

    though, on second thought, it is also supposed to support 18, 0, 18, so a modified carnetix psu might work..

  6. #6
    Newbie
    Join Date
    Jul 2003
    Location
    Rochester NY
    Posts
    6
    Quote Originally Posted by soundman98 View Post
    unfortunately, the rlc has 2 outputs and 1 input one passthrough output, one amplified output, and a single balanced input..

    that preamp looks like a pretty nice diy project-- powering it in-car is still going to be a issue-- it looks like the psu needs to output 15, 0, 15v. and i don'te really know of any auto-psu's that do that.

    though, on second thought, it is also supposed to support 18, 0, 18, so a modified carnetix psu might work..
    Well, the +-15V is for the discrete buffers, the part of the project I would probably adapt is the arduino controlled stepped attenuator, source selector, and LCD. But thats so far off in my plans I shouldn't even be thinking about it.

    Its hard to limit the scope of what I'm trying to do, but thats a good way to not ever get anything installed :-p
    - Steve

Similar Threads

  1. Replies: 11
    Last Post: 05-06-2008, 08:56 AM
  2. Planning BMW E36 install
    By Flexner in forum General Hardware Discussion
    Replies: 3
    Last Post: 01-03-2008, 05:37 PM
  3. Replies: 35
    Last Post: 08-28-2007, 10:05 AM
  4. Planning out my install, 1 Question!
    By slidesear in forum General Hardware Discussion
    Replies: 6
    Last Post: 07-25-2007, 06:08 PM
  5. Planning '07 Nissan Titan Install
    By daviszr1 in forum Newbie
    Replies: 3
    Last Post: 05-10-2007, 07:47 PM

Bookmarks

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •