Very easy audio switch box?

J

jdonnici

Guest
I've got an idea for a very simple project, but have been unable to
find some info for it online... before I make a go of it "blind", I
figured I'd post for some ideas.

Basically, I've got 3-4 audio devices in my office and one set of
speakers. All the audio devices have 1/8" stereo jacks for ourput
while the speakers use a 1/8" stereo plug. Currently, I unplug and
plug those speakers as needed, but it can be unwieldy. What I'd
like is a simple little box with some switches so that I could
quickly switch between source devices. I don't see a need for
having more than one device selected at a time.

Radio Shack makes a simple little "stereo audio source selector"
switch box, which would be perfect, but all the I/O on it is RCA
phono. By the time I buy it and all the little adapters to go from
RCA phono to 1/8 jack/plug, I could probably do it cheaper on my
own... or at least have more fun with it by the time I'm done.

Now... is it safe to assume that I can just buy a small project
box, some jacks and some switches, and wire it all up inside the
box? Or will I need to do something with resistors or other
components to not screw up the sound quality (and/or the
equipment!)?

I know very little about the inner workings of electronics, but I'm
happy to learn and this seems simple enough. I do own a soldering
iron (from a project waaay in the past), as well as other various
tools... and RS is right around the corner. :)

Any insights or pointers to relevant URLs would be most
appreciated. I tried googling on all sorts of combinations of
"stereo audio switch box", etc, but mostly seemed to find amp-
related projects.

Thanks in advance for any help,

J
 
In article <MPG.197d472274c3afb1989684@news-50.giganews.com>,
jdonnici <jdonnici@why-ay-aich-oh-oh-dot-com.com> wrote:

I've got an idea for a very simple project, but have been unable to
find some info for it online... before I make a go of it "blind", I
figured I'd post for some ideas.

Basically, I've got 3-4 audio devices in my office and one set of
speakers. All the audio devices have 1/8" stereo jacks for ourput
while the speakers use a 1/8" stereo plug. Currently, I unplug and
plug those speakers as needed, but it can be unwieldy. What I'd
like is a simple little box with some switches so that I could
quickly switch between source devices. I don't see a need for
having more than one device selected at a time.

Radio Shack makes a simple little "stereo audio source selector"
switch box, which would be perfect, but all the I/O on it is RCA
phono. By the time I buy it and all the little adapters to go from
RCA phono to 1/8 jack/plug, I could probably do it cheaper on my
own... or at least have more fun with it by the time I'm done.

Now... is it safe to assume that I can just buy a small project
box, some jacks and some switches, and wire it all up inside the
box? Or will I need to do something with resistors or other
components to not screw up the sound quality (and/or the
equipment!)?

I know very little about the inner workings of electronics, but I'm
happy to learn and this seems simple enough. I do own a soldering
iron (from a project waaay in the past), as well as other various
tools... and RS is right around the corner. :)

Any insights or pointers to relevant URLs would be most
appreciated. I tried googling on all sorts of combinations of
"stereo audio switch box", etc, but mostly seemed to find amp-
related projects.

Thanks in advance for any help,

J
Click to expand...
A simple switch is all you need; no terminators or mixers. RS sells a 2
pole, 6 position rotary switch.

There is one possible problem, though - a ground loop. If you get AC
hum, you'll need a 3 pole switch so you can switch the ground too. Some
electronics stores have switch components so you can build any custom
switch.
 
jdonnici <jdonnici@why-ay-aich-oh-oh-dot-com.com> wrote in message news:<MPG.197d472274c3afb1989684@news-50.giganews.com>...
I've got an idea for a very simple project, but have been unable to
find some info for it online... before I make a go of it "blind", I
figured I'd post for some ideas.

Basically, I've got 3-4 audio devices in my office and one set of
speakers. All the audio devices have 1/8" stereo jacks for ourput
while the speakers use a 1/8" stereo plug. Currently, I unplug and
plug those speakers as needed, but it can be unwieldy. What I'd
like is a simple little box with some switches so that I could
quickly switch between source devices. I don't see a need for
having more than one device selected at a time.
Click to expand...


You can do it with a two-pole rotary switch with the number of
positions corresponding to the number of audio sources you have - or
maybe one or to more to allow for future additions.

You will need to decide how to connect the sources to the box, (1/8"
stereo jacks and leads with a plug on each end, for instance.)

The "ground" side of each of the inputs need to be connected together
and to the output "ground".

The left channel "hot" inputs each go to a switch position on one
section of the rotary switch, the right channel "hot" inputs to the
corresponding positions on the other switch section. The switched
(moving) contact of one section goes to the left connection on a 1/8"
output jack, and the switched contact of the other section ...... you
can guess the rest.

If you have a choice between a "make before break" and "break before
make" switch, choose the latter.
 
Hello,
This is a very simple project, and all the parts needed are available
at Radio Shack. And you won't need any resistors. I recommend using an
aluminum box for shielding purposes, and the common ground connection
can be made through the box itself by simply mounting the jacks on the
panel, so you'll just need two wires from each jack going to the
switch. Here's a parts list:

Switch:
2 pole 6 position non-shorting rotary
P/N 275-1386
$2.99
(This switch has 6 positions which is more than you need, so you can
leave the other positions unconnected, or use 6 jacks for future
expansion.)

Jacks:
1/8" 3 conductor open circuit chassis mount
P/N 274-249
$2.99 / pkg. of 2

Minibox:
P/N 270-238
$2.99

Of course, you'll also need some wire, rosin core solder, a drill and
bits for making the holes, pliers and wire strippers, and a knob if
you want. Here's a crudely drawn wiring diagram that should get you
through. If you're using a text-only server, you can get the diagram
from my site at
http://mywebpages.comcast.net/bobrowton/diagram.gif

While you're there, you might check out the very cool Honda ad at
http://mywebpages.comcast.net/bobrowton/index.html

Good luck.
 
On Tue, 15 Jul 2003 07:49:45 -0600, Robert Rowton
<nospamplease@myrealbox.com> Gave us:

Hey dumbshit! Do NOT post binaries into non binary groups!
 
In article <IN4Ra.439613$3C2.12020592@news3.calgary.shaw.ca>,
"Bullwinkle Jones" <bullwinkle_01_01@hotmail.com> wrote:

"DarkMatter" <DarkMatter@thebarattheendoftheuniverse.org> wrote in message
news:3k79hv440ntsbhde5rutle6v6rca8ddhun@4ax.com...
On Tue, 15 Jul 2003 07:49:45 -0600, Robert Rowton
nospamplease@myrealbox.com> Gave us:

Hey dumbshit! Do NOT post binaries into non binary groups!

Wowee.. lets not get _too_ angry. It was only a 10k binary, after all. Even
the poor soul out there who still uses a 14.4kbit modem wouldn't even have a
problem.
Click to expand...
You still can't do it. Most news servers filter out binaries from text
groups. Some people also run bots that cancel binaries in text
newsgroups. Whatever the case, it never arrived here.
 
On Tue, 15 Jul 2003 23:05:47 -0600, jdonnici
<jdonnici@why-ay-aich-oh-oh-dot-com.com> wrote:

1 - Is that possible, or would that screw things up in terms of the
signal flow and/or make it much a more complex effort?
Click to expand...
Not more complex but, potentially, a problem for the devices. Multiple
simultaneous loads might exceed the capability of your source device.
It also makes it possible for their to be nothing connect although
this is less of a problem in general.

2 - If it is possible, which type of switch would be the most
correct to use? I saw plenty of SPST, SPDT, and DPDT switches... I
could see the differences on them visually, but wasn't sure which
would be most appropriate. Also the RS packaging doesn't have any
type of wiring diagram, so it was hard for me to see precisely how
I'd wire it all together.
Click to expand...
Stick with the diagram/circuit you have.

3 - Would it be reasonable for the output side of each toggle
switch to be wired to the output jack? Seems I'd have 4-6 pairs of
wires going into that one jack and may need to be more creative to
make that work.
Click to expand...
Vide supra.

Next.. I did find the 2-pole, 6-position rotary switch and that
diagram was very helpful in terms of helping me see the way that
would all be connected.

The concern I had with that is that the "post" for the switch
seemed like it was much longer than any of the matching knobs would
really work for.
Click to expand...
Intentionally. You cut off as much as necessary to make it work.

In other words... I drill a hole for it, mount the rotary switch to
the inside of the box, and then stick a knob on the end of it --
but the base of that knob could be sticking out a half-inch or some
from the box's external surface.
Click to expand...
Vide supra.

How is that normally handled? Was I not looking for the right knob,
is that post usually trimmed to size (yikes... I'd be afraid of
ruining the switch), or am I missing something else altogether?
Click to expand...
Vide supra.

Kal
 
"Kalman Rubinson" <kr4@nyu.edu> wrote in message
news:ldrahvkijeaqmujlp4d1gf0g4jj60tuami@4ax.com...
On Tue, 15 Jul 2003 23:05:47 -0600, jdonnici
jdonnici@why-ay-aich-oh-oh-dot-com.com> wrote:

1 - Is that possible, or would that screw things up in terms of the
signal flow and/or make it much a more complex effort?

Not more complex but, potentially, a problem for the devices. Multiple
simultaneous loads might exceed the capability of your source device.
It also makes it possible for their to be nothing connect although
this is less of a problem in general.
Click to expand...
Well, he could do this, he'd just need to buffer it with an op-amp or
somesuch.
 
On Thu, 17 Jul 2003 03:39:55 GMT, "Bullwinkle Jones"
<bullwinkle_01_01@hotmail.com> wrote:

"Kalman Rubinson" <kr4@nyu.edu> wrote in message
news:ldrahvkijeaqmujlp4d1gf0g4jj60tuami@4ax.com...
On Tue, 15 Jul 2003 23:05:47 -0600, jdonnici
jdonnici@why-ay-aich-oh-oh-dot-com.com> wrote:

1 - Is that possible, or would that screw things up in terms of the
signal flow and/or make it much a more complex effort?

Not more complex but, potentially, a problem for the devices. Multiple
simultaneous loads might exceed the capability of your source device.
It also makes it possible for their to be nothing connect although
this is less of a problem in general.

Well, he could do this, he'd just need to buffer it with an op-amp or
somesuch.
Click to expand...
He's having technical difficulties wiring a switch; why advise him to
start messing with buffers?

Kal
 
In article <7kedhvgkqud5vn71evutuc35iiunu154bo@4ax.com>, kr4
@nyu.edu says...
He's having technical difficulties wiring a switch; why advise him to
start messing with buffers?
Click to expand...
Fair question... and not to worry -- I'm going with the nice simple
rotary switch. ;)

I picked up a couple of 'build it yourself' kits the other day, as
well as a book called something like 'electronics projects for
musicians' -- in the hope of learning more about this new world.
I'm a software developer by day, so I'd love to start learning
something about circuits and hardware logic.
 
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