auto switching aux-in mod

Hi folks,

 

I'd read the write-ups on installing an aux-in connector for iPods, XM, 8-track decks, etc, but didn't pay that much attention until I got a heck of a deal on a 2 gig iPod Nano. Now I had to have some way to hook that little bundle of flash memory into my car stereo.

 

I tried a FM transmitter I had left over from a carputer project I built about eight years ago, but guess what, FM transmitters still sound like crap.

 

I really liked ipoduser's solution

(http://legacygt.com/forums/showthread.php?t=21047&highlight=aux)

but didn't like having to flip a switch or install relays - I'm lazy, and that's too much work

 

What I ended up doing was installing a stereo mini-jack with two pole switching and wiring that in between the tuner out and amp in as described in ipoduser's post - here's the data sheet of a product similar to what I used.

 

http://www.cui.com/pdffiles/SJ1-3515.pdf

 

Basically, when nothing is plugged into the jack, the output from both channels of the radio's tuner module is routed back into the amp like what would normally happen inside the radio.

 

When a mini-stereo patch cable is plugged into the jack, however, the signals coming down the line from the iPod on the other end of the patch cable go into the amp, and I'm rockin' with a super clear direct connect aux in.

 

I was worried about noise being introduced due to having to run five wires to the jack, so I used shielded cable. There is absolutely no noise, however, and this is with about four feet of wire running out of the radio to the jack. That means in radio mode the audio signal is running from the tuner module four feet to the jack, and then four feet back to the amp. Eight feet of wire, and no noise!

 

I'll post some pictures and perhaps a back of the napkin schematic after I get a small project box to mount the jack in - the jack will live somewhere near the e-brake or cup holders, but I didn't want to drill any holes in my plastics yet.

 

Total cost on this was about $8 - $3 for the jack, and $5ish for the wire. I think I got ripped off on the wire

 

I might still build more circuitry into this system - I'd like to hook a bluetooth earpiece into the radio, and would like it to auto switch. I'll keep you folks posted!

 

Thanks to ipoduser for the hard part of finding the tuner outs, and to jazzymt for the excellent radio removal guide. They did the hard parts - I just soldered in a different part.

 

Also, I'm not liable if you break your radio, set your car/house/cat on fire, die from solder-related lead poisoning, or can't get a date even with this mod. You have been warned - you probably shouldn't do this to your radio.

 

-Ryan

hrm - nicely done... this may give me the reason to splice those traces.

Yea, it's been working fine since I installed it - I've been blasting Judas Priest and the White Stripes out of my stereo since I installed this mod.

 

This evening, I installed a small plastic box immediately behind the end of the e-brake and before the armrest to hold the jack in place. It looks pretty nice, and the jack's not flopping all around now. Definitely worthwhile.

 

-Ryan

Yea yea yea! Right now, the only pic you'd get is of a black plastic box with a wire going into it and a headphone jack on the front of it. I will cellphonepicize it after work.

 

-Ryan

Definitely in for more info!

 

So the radio signal cuts when you plug in the patch cord? No more switches or relays? I can have AM/FM/Ipod/CD and all I have to do to get the ipod is have the radio selected and ipod plugged in? Cheap and relatively simple to perform? This may bump Clear/Black headlights as my first modification.

 

Good job and many thanks if you post up a quick walkthrough and diagram/pics...

I will get on that walkthrough when I get some time this weekend. The only * in this mod is that you must turn off the radio or turn the volume down to zero prior to plugging or unplugging the patch cable from the jack. I sometimes think that a switch might be nicer, but you still have to turn down the volume with a switch or else you get that "thump!" through your speakers. It's nice in the no extra components aspect.

 

To get you started, read up

http://legacygt.com/forums/showthread.php?t=21047&highlight=aux

 

This is the meat of the install - you're going to be running wires from the tuner side to the headphone jack and then back from the headphone jack to the amp side of the radio. I used six conductor grounded shielded wire, but even stranded shielded CAT5 or CAT6 would probably work. You have to make sure that you ground the shield to the radio ground, or else you don't really get the benefits of the shield.

 

The part of this mod with the biggest pucker factor is cutting the traces on the circuit board of the radio. You can solder wires across the cut later on, but this is not as easy as bolting a stock uppipe back on to take it in for warranty work. If you cook your radio, you're effed.

 

Anyway, I'll get some pictures, but in the meantime here's a cameraphone snap of the schematic. There's not too much to it...

 

-Ryan

Here's a pic of how I have the headphone jack mounted.

 

I use a shorty patch cable to hook up my iPod, and set the iPod on top of the cup holder cover thingy as the rubber prevents the iPod from sliding.

 

The box was the enclosure for one of those old-school car alarm vibration sensors. I put a hole in it with the drill press for the headphone jack, and that was about it.

 

-Ryan

Well, I picked up a 3.5mm Phone Jack (qty. 2, Philmore P/N 502J, LKG Industries) for $1.59 at You-Do-It Electronics the other day. I also grabbed a 25' shielded patch cord while I was there to use as the in and out cables since they have two channels and the common ground. Hopefully there wont be clearance issues with the cable. I plan on mounting the jack inside the armrest storage area right next to the power outlet. Then I will use the belkin dock connector with a small patch cord and keep it tucked away neatly. That convenient groove between the armrest and the bin will let me keep the ipod on the cup holder cover or inside.

 

I will be reading into the stereo removal this weekend and have one of the talented EE's at work do the small stuff. Will post back with some pics/notes.

what is the exact name of this 'jack'.. ?

 

im trying to buy one and cannot figure out what it exactly is..

 

where can i get it.. ? radioshack.. ?

It is a simple 3.5mm headphone jack... The same type of jack you your plug headphones into on any portable audio gear. If you've ever had a boombox, did you notice that when you plug in the headphones the speakers stop playing? It's the same mechanism thats doing the switching except we're using it as an input rather than an output.

 

The ones I picked up are transparent on one side so you can see the mechanism move when you put in the plug.

 

Make sure you have a competent electrical guy to do the cutting/soldering, you don't want to fry your board. Still haven't done it myself, maybe this weekend?

Nice!!!

 

Exactly what I was looking for.

 

Need to take some soldering classs now!