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View Full Version : Show idea: 1/8" stero jack switch-box


waubers
08-03-2008, 10:06 PM
I have a Mazdaspeed 3. I love the car, and can't say enough positive about it.

My previous Mazda 3 had some faults, but the most annoying of them was the lack of a line in jack on the stereo. This issue is solved in my MS3 but, it's only a single input, and soon I'm going to need 3.

Why?

Well, if I can figure out a way to do it, this would be the setup:

Input 1: Sirius receiver (I <3 my Satradio, makes my 45 minute drive to work easier).

Input 2: Zune. Yes, I said Zune. I'm intending to install it for the express purpose of it's ability to use wifi. I want to be able to pull into my garage, fire up the zune, tell it to sync a folder full of updated podcasts off of my media server which downloads them automatically without me having to do anything.

Input 3: My Blackberry. Why? Well, because it'll stream radio really well. I live out in the boonies. Terrestrial radio sucks balls, and I like to listen to some stations that there's no way I can pick up in my car otherwise. The blackberry makes this happen, in splendid fashion, even on 1X data connections, and since I travel almost exclusively on the Interstates, I almost always have coverage. Also, think about if you have an iPhone, and how nice it would be to stream pandora of last.fm with relative ease.

Yes, this might seem a bit over the top, but it's 2008 and if I can't have a car that flies, I at least want one that has decent sounding audio from a variety of sources.

To that end, the MS3 is a PITA. for whatever reason, Mazda didn't install a ground-loop isolater, so if I plug my Sirius in without one hooked up it sounds like I'm listening to AM radio during a thunderstorm.

So basically, what I want (ideally) would be a compact, hopefully un-powered, box with at least 3 inputs for 1/8" stereo audio, a built in ground-loop isolator and a single 1/8" audio out cable that I can plug right into my MS3. It needs to be relatively easy to select inputs, unlike now which requires pulling over to the side of the road and re-doing a bunch of audio cabling.

Tall order I know, but it would be pretty slick to get it working. I've found similar devices, but they're all or RCA style discrete LR channel cables, like you'd use in a home entertainment center.

I'm not opposed to trying to build my own, but I'm a noob at this kinda thing so any guidance would rock.

Suggestions? I think this would make for an interesting Systm episode, especially if you're able to incorporate the ground-loop isolator, which a lot of people might not otherwise think of.

haku
08-04-2008, 03:14 AM
Should be a fairly straightforward project, getting the 3.5mm stereo plug, 3 panel mount 3.5mm stereo sockets, enclosure & ground loop isolator won't be a problem, how you switch between the three inputs may take some looking into, maybe something like this:
http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=200243415399
but I'm not exactly sure how you'd wire it up, it's been a long time since I used a rotary switch especially one with multiple poles. As I say the swtiching method will need some looking into.

velocitapaola
08-04-2008, 08:22 AM
Should be a fairly straightforward project, getting the 3.5mm stereo plug, 3 panel mount 3.5mm stereo sockets, enclosure & ground loop isolator won't be a problem, how you switch between the three inputs may take some looking into, maybe something like this:
http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=200243415399
but I'm not exactly sure how you'd wire it up, it's been a long time since I used a rotary switch especially one with multiple poles. As I say the swtiching method will need some looking into.

That's how I would do it... though you shouldn't necessarily need a rotary switch; a single pole triple throw (SPTT) rocker or toggle should work fine. Also, perhaps Patrick could experiment with making his own ground loop isolator with a 1:1 isolation transformer or maybe chokes.

To get more complicated (but also more interesting), he could make a completely solid state device using MUXes or bus switches. With the addition of a few JK latches, you could use momentary pushbuttons for a pretty sleek interface.

Here's something similar that was designed for video:

http://www.engadget.com/2007/03/13/how-to-make-a-solid-state-a-v-switcher/

dark_shroud
08-04-2008, 04:16 PM
Personally, I would use a three way toggle instead of using a rotary switch in a car just to make it easier.