Simple question: what type of switch is this

[Michael Levin]

I'm sure this is a very simple question, but I'm now all confused as to
which is double-pole double-throw and all that. What I want is simple: I
have one of those fake tapes with an input that allows me to play other
devices through my car stereo. The input is a male plug that is like what
you have on a set of standard small earphones. I have 2 devices: a SIRIUS
satellite radio receiver, and an iPod, both of which have female jacks that
this thing can plug into. All I want is to be able to have a selector so
that I can choose between the two of them without having to plug and unplug
(since they're both hidden in my glove box). First, does something like this
already exist that I can buy? I've tried a web search but don't really know
what terms are best - I haven't found anything. Barring that, I'll make one
myself. I bought a Y splitter, but if both objects are connected, there's a
weird hum. So, what I want is a simple switch that will break the connection
on one of the sides at a time. Like this:

iPod -----0 0------- \
0--0 >-------Y splitter---- car stereo
Satellite -----0 0------- /

the 0--0 thing in the middle should be in one of two positions, connecting
either the top or bottom circuit (but is not itself connected to anything).
This, if I'm not mistaken, is a single-pole, double-throw switch, right? The
problem is that my wires aren't single (like in the diagram above) but
triple, since it's stereo. So, what I need is a switch like that but so that
each position completes 3 circuits, not just one. What is that called? Is it
DP3T? What part am I looking for? Any advice would be appreciated!

Thanks,

 

[David Harmon]

On Sun, 19 Mar 2006 17:46:21 -0500 in sci.electronics.basics,

iPod -----0 0------- \
0--0 >-------Y splitter---- car stereo
Satellite -----0 0------- /

the 0--0 thing in the middle should be in one of two positions, connecting
either the top or bottom circuit (but is not itself connected to anything).
This, if I'm not mistaken, is a single-pole, double-throw switch, right? The
problem is that my wires aren't single (like in the diagram above) but
triple,

That would be a three pole double throw switch; except that it's OK
for both ground wires to be connected all the time so you really
only need a double pole double throw, DPDT which are very much
easier to find.

 

[Michael Levin]

On Sun, 19 Mar 2006 17:46:21 -0500 in sci.electronics.basics,


That would be a three pole double throw switch; except that it's OK
for both ground wires to be connected all the time so you really
only need a double pole double throw, DPDT which are very much
easier to find.

ok, cool; which wire, on one of those standard stereo plugs, is the ground
wire? The thing has 3 sections. Which of the sections is the one that's ok
to leave connected?

Thanks,

Mike

 

[Michael Levin]

On Sun, 19 Mar 2006 17:46:21 -0500 in sci.electronics.basics,


That would be a three pole double throw switch; except that it's OK
for both ground wires to be connected all the time so you really
only need a double pole double throw, DPDT which are very much
easier to find.

And just for my edification, the 3PDT should have 12 contacts, right?

Mike

 

[Chris]

ok, cool; which wire, on one of those standard stereo plugs, is the ground
wire? The thing has 3 sections. Which of the sections is the one that's ok
to leave connected?

Thanks,

Mike

Hi, Mike. Please take the time to read two short Wikipedia articles:

http://en.wikipedia.org/wiki/Tip_ring_sleeve
http://en.wikipedia.org/wiki/Switch

This will give you the technical terminology you need to understand
your wiring problem.

You should go to Radio Shack and get a small DPDT switch, two stereo
jacks and a stereo plug. Then you can wire it up like this (view in
fixed font or M$ Notepad):

| Jack 1
| .----.
| | |
| | To---------.
| | | | SW1A
| | | '---o Plug 1
| | Ro------. __--o--. .----.
| | | | .---o | | |
| | | | | | '---oT |
| | So---. | | | |
| | | | | | | | |
| '----' | | | .---oR |
| | | | | | | |
| Jack 2 | | | | | |
| .----. | | | | | .-oS |
| | | | '--)---o | | | |
| | To---)-----' __--o--' | '----'
| | | | .------o |
| | | | | SW1B |
| | Ro---)--' |
| | | | |
| | | | |
| | So---o------------------'
| | |
| '----'
|
(created by AACircuit v1.28.6 beta 04/19/05 www.tech-chat.de)

In the wiring diagram above, T stands for Tip, R for Ring, and S for
sleeve. You can see in the wiring diagram that the two sleeves can be
connected together.

If you keep the wiring short on your selector switch (a few inches),
you can use 22AWG stranded hookup wire without problem. If you're an
audiophile, you should look for a DPDT shielded switch with gold
contacts which can do dry circuit switching (very low voltage at low/no
current), and use shielded signal wire for the hookup. But for us mere
mortals, the above should be OK for occasional use, as long as you use
a new switch.

Good luck
Chris

 

[Peter Bennett]

And just for my edification, the 3PDT should have 12 contacts, right?

Mike

No - only 9. Each pole of a double-throw switch has three contacts -
the common (moving) contact, and two fixed contacts, one for each
position of the switch.

In your drawing above, your middle moving part should be connected
directly to the car stereo input - you don't need the Y splitter
there.


--
Peter Bennett, VE7CEI
peterbb4 (at) interchange.ubc.ca
new newsgroup users info : http://vancouver-webpages.com/nnq
GPS and NMEA info: http://vancouver-webpages.com/peter
Vancouver Power Squadron: http://vancouver.powersquadron.ca

 

[Jasen Betts]

I'm sure this is a very simple question, but I'm now all confused as to
which is double-pole double-throw and all that. What I want is simple: I
have one of those fake tapes with an input that allows me to play other
devices through my car stereo. The input is a male plug that is like what
you have on a set of standard small earphones. I have 2 devices: a SIRIUS
satellite radio receiver, and an iPod, both of which have female jacks that
this thing can plug into.

iPod -----0 0------- \
0--0 >-------Y splitter---- car stereo
Satellite -----0 0------- /

the 0--0 thing in the middle should be in one of two positions, connecting
either the top or bottom circuit (but is not itself connected to anything).
This, if I'm not mistaken, is a single-pole, double-throw switch, right? The
problem is that my wires aren't single (like in the diagram above) but
triple, since it's stereo. So, what I need is a switch like that but so that
each position completes 3 circuits, not just one. What is that called? Is it
DP3T? What part am I looking for? Any advice would be appreciated!

3PDT

three pole (switches three circuits) dual throw (two "on" positions)


but.

you only need to switch the left and right signals the common can be left
connected to both devices

1
2
IPod-L --------o--__
~~o--------------------- L
Sat-L ---------o

3


IPod-c ---.

-------------------------------- C

Sat-c ----'


4
5
IPod-R --------o--__
~~o--------------------- R
Sat-R ---------o

6




STERIO PLUG (not to scale) ################>
# # common
_ ______ ______________# #____________________
/~--__ / ## ## # # | |
/ ~~ ## ## # # | left | |
/ ## ## # # | |~~~~\ \ |
\ ## ## # # | | o ) |\ |
\ __ ## ## # # | |____/ |/\|
\_--~~ \_##______##______________# # | right / \
# # ~~~~~~~~~~
# #
LEFT RIGHT COMMON ###############>


______
/ /|
/____ / |
|1 2 3| |
| | /
|4 5 6|/
~~~~~

back of DPDT switch

 

[Jasen Betts]

And just for my edification, the 3PDT should have 12 contacts, right?

that depends on the construction, for typical toggle and rocker switches
that'd be right.

but only 9 external terminals

3p3t would have 12

Bye.
Jasen

 

[ray13]

Common is common why do you peeps insist on switching the common? DPDT
is the way to go.
Forget the ground or common switching, connect all grounds together.
Case in point: in ole fashion VCR's the channel 3/4 modulator doesn't
switch freaking ground, when it selects it's inputs.

 

[Rich Grise]

I'll make one myself. I bought a Y splitter, but if both objects are
connected, there's a weird hum. So, what I want is a simple switch that
will break the connection on one of the sides at a time. Like this:

iPod -----0 0------- \
0--0 >-------Y splitter---- car stereo
Satellite -----0 0------- /

You don't need that much switch, or the Y adapter. Each channel of your
stereo signals only needs a SPST, and you can lose the Y adapter:

1A

iPod R -----0
\ 1C

| 0------ car stereo R
1B |

Satellite R -----0 | |
2A |
iPod L -----0 | \ 2C
0------ car stereo L 2B
Satellite L -----0

So, you'd look for a simple DPDT switch.

Cheers!
Rich

 

[John Fields]

---
Let's see...

29 Mar 2006
- 19 Mar 2006
-------------
10 days.

Hmmm...

Lately, Rich, it seems your replies are often late enough that the
subject matter has already been hashed over enough that your input
is superfluous.

Are you aware of that?

The delay thing, I mean.

 

[ray13]

Hey as long as google provides me with a reply button I could keep this
thread going forever. Regardless of the time between posts.

And to sum up DPDT is the way to go. They didn't switch the grounds in
the ole VCR's when switching inputs.

 

[Rich Grise]

---
Let's see...

29 Mar 2006
- 19 Mar 2006
-------------
10 days.

Hmmm...

Lately, Rich, it seems your replies are often late enough that the subject
matter has already been hashed over enough that your input is superfluous.

Are you aware of that?

The delay thing, I mean.

Yes, but I usually don't notice it until it's too late. I usually read all
the way through NG, so the whole thing gets marked as read. The next day,
something suddenly shows up, which I won't realize is a week or more old,
because I haven't seen it or any part of the thread before.

I guess I'll chalk it up to a flaky server (Verizon ADSL), and pay more
attention in the future.

Thanks,
Rich

 

[ray13]

good come back, once you hit that post button it's all over the fat
lady done sang.