TJOtala

After I had finished the Storage Brick project, I wanted to improve the music listening experience while driving in my car. Unfortunately my current car audio system does not have a line-in connector, so I had to build one myself.

The basic project concept is similar to the AutoMP3 article written by Ralph Cottenham. I built my setup into a 1997 Nissan Pathfinder.

Tools

• wire cutter/stripper
• continuity tester (I used a Sperry DM-5300 digital multimeter)
• soldering iron
• drill

Materials

• FM modulator (I found an Audiovox model at a local car audio dealer)
• antenna patch cables (I needed special patch cables to hook into the Nissan “diversity” antenna setup)
• shrink tubing or electrical tape
• cable with RCA male jacks in one end
• 1/8″ male-to-male mini plug stereo cable
• 1/8″ female mini plug socket (panel mount)
• on/off switch
• 12V lamp

Most of these tools & supplies can be found in your nearby electronics store such as RadioShack.

Instructions

Please note that these instructions assume certain level of knowledge and understanding of basic electronics and mechanics. If you do not possess these skills, please consult your local car audio dealer instead of trying this at home. There is a very real possibility of electrocution here, or at the very least you’ll blow a few fuses (I did, so take my word). I take no responsibility over any damage you might do to yourself, your car, or your iPAQ.

Take apart your dash. You may also want to detach your car battery cable before sticking your hand inside the dash. On my Pathfinder, the dash is attached with two sheet metal screws at the bottom, and the top is held in place with plastic tabs. Simply unscrew the screws and pry the dash away starting from bottom. You will need to detach half dozen connectors leading to the dash components: emergency blinker, cigarette lighter, rear windshield wiper switch.
Mount the FM modulator in a suitable place and attach the modulator to the car wiring as instructed in the installation guide. On my Pathfinder, I mounted the FM modulator underneath the radio in a convenient empty spot. Cable straps are the magic that holds universe together. I wired the modulator into the 12V supply that leads into the cigarette lighter.
Install the lamp, on/off switch, and a 1/8″ female mini plug in a suitable place in your dash. The picture on the right is somewhat misleading as the thick cable with the 1/8″ male plug is the other end of a RCA-to-mini cable that I later cut to connect to the in-dash 1/8″ female mini plug. Having a 1/8″ male mini plug allowed me to test the setup before cutting up the dash panels. You may want to use connectors on all wiring leading to the dash, as this makes it easier to take the dash apart again in the future when you add something else to it. On my Pathfinder, there are several empty pop-out plastic panels ideal for this use. Cramming all three components inside a single panel was something of a chore but the end result looks pretty nice (except for the dust).
Re-check all wiring and then tune the radio to the selected channel. Let ‘r rip!

Summary

This was certainly an interesting project. I learned a great deal about automotive electronics in the process, including where all of the fuses are in my car and just how difficult those particular fuses can be to replace. I kept blowing a 10A fuse first by accident (shorted wires), and then every time while using the FM modulator in practice. This was extremely annoying as every time it happened it took out my dash lights, emergency blinker and tail lights. Finally I changed the wiring configuration to piggyback on the cigarette lighter wiring instead of the spare set of wires I had come across inside the dash. This fixed the fuse blowing for good.

I can only guess that the FM modulator draws quite a bit of juice and it overloaded whatever circuit that spare set of wires was intended for. I was too cheap to pay Nissan about US$100 for the service manual for my car ;-}

This entry was posted on Thursday, July 25th, 2002 at 1:00 am and is filed under Windows CE, PocketPC, Hardware, Computers. You can follow any responses to this entry through the RSS 2.0 feed. Both comments and pings are currently closed.