#1
Hi, an easy noob question for y'all.

I want to build a simple A/B audio switchbox that has two 3.5mm stereo inputs and a single 3.5mm stereo output. I want to share a set of Boston Acoustics PC speakers + sub-woffer between two separate inputs from my Windows 7 PC ("A") and the headphone out jack on my small 19" HDTV ("B"). For my needs I'll be using either A or B but never both at the same time.

I want to use a small enclosure and 3PDT switch from Small Bear and use three 3.5mm stereo jacks from Mouser.com

Here are the parts I plan to use:

3PDT toggle switch:


Hammond 1590A enclosure:


3.5mm Stereo connector (three of 'em):


So: how do I wire this up? Let's say that the 3PDT switch has the following contacts:

1 --- 2 --- 3  
4 --- 5 --- 6  
7 --- 8 --- 9 


And let's say that the three 3.5mm stereo jacks each have contacts labeled:

G (for ground)
R (for ring)
T (for tip)


Finally, let's say that two input jacks are labeled "1" and "2", respectively, and the output jack is labeled "X".

So, we have:

1G, 1R, 1T
2G, 2R, 2T
XG, XR, XT


Can someone please tell me how each of the jacks should be connected to the switch? I'm just looking for a simple mapping table, like this:

1: 1R
2: 1G
3: 1T

...and so on...
"In Power Trios I Trust..."
Gibson SG Classic, Fender CP Jaguar Special HH, '65 RI Mustang
'65 Ampeg Gemini I G-12 Combo, Orange Tiny Terror
#2
On another site, someone just said that a 3PDT switch is overkill for this project. He said a SPDT switch would work fine (despite the fact that the other two projects I found on the web similar to this one both used DPDT switches).

Would a SPDT switch work for a stereo circuit?
"In Power Trios I Trust..."
Gibson SG Classic, Fender CP Jaguar Special HH, '65 RI Mustang
'65 Ampeg Gemini I G-12 Combo, Orange Tiny Terror
#3
Someone over at OffsetGuitars.com just posted this for me:

"In Power Trios I Trust..."
Gibson SG Classic, Fender CP Jaguar Special HH, '65 RI Mustang
'65 Ampeg Gemini I G-12 Combo, Orange Tiny Terror
#4
That diagram should work just fine

if you wanted a status LED, that's when you'd need a 3pdt

edit: just took another look...
The tip, ring and sleeve of the jacks are messed up. You need to switch the tips and rings, with the grounds(sleeves) connected.

The basic ideas right, though

edit2: damn, I was looking at it wrong the second time
diagrams all good
Last edited by james4 at Dec 30, 2009,
#5
the reason people would use a DPDT for a mono jack is to ground the unused input/ouput. doing it this way just opens unused connection, which is fine, but can cause a bit of hum. if you want to do a stereo setup with grounding of the unused connections you would need a 4PDT switch. they make them, and the one at smallbear isnt that much more expensive. not entirely neccessary, but i probably would do it.