Smart audio splitting from a PC?

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Aaryn015

104 posts

Master Geek

#75955 26-Jan-2011 14:13

Hi all,

I'm putting together a kiosk that has two audio targets:

1. An amplifyer powering two small speakers
2. A 3.5mm headphone extension that is mounted on the front to allow users to plug in their own headphones.

Both the extension and the input cable to the amp have a 3.5mm jack on the PC end.

The idea is that I would like the speakers to be the default audio output UNLESS there is a set of headphones plugged into the extension on the font. Obviously when the extension is plugged into the pc output, the PC assumes that there are headphones plugged in regardless of whether there are headphones plugged into the extension or not.

Is anyone aware of an intelligent switch that can recieve one input (from the PC) and intelligently switch between speak output and headphones when headphones are detected? Is this even possible?

Cheers for any ideas.

Aaron

Speedy885

182 posts

Master Geek

#431540 26-Jan-2011 19:23

the only way i can think of is to use speakers that have a built in headphone socket like these:

http://pricespy.co.nz/product.php?p=38794

which when you plug in headphones the speakers are disabled.

gzt

17105 posts

Uber Geek

Lifetime subscriber

#431633 27-Jan-2011 00:07

+1 above. As well, check the behaviour of the headphone socket on the speakers. Some use only the direct sound card output directed through the speaker headphone socket which is useful. Some speaker headphone sockets are limited in volume a bit - also useful. Hacking the speakers to mount the headphone socket remotely (to keep the switching) will not be difficult, you will need shielded cable, and avoid proximity with a/c and data lines on the cable path.

Seen some discussion on ubuntu forums about a headphone jack sense feature. Might be worth more research to see which hardware supports it.

I believe Mac has this feature, and 3rd party software to control it but I can't tell you any specifics.

gzt

17105 posts

Uber Geek

Lifetime subscriber

#431719 27-Jan-2011 10:03

Actually, if you can identify a cheap sound card with a jack sense feature you might as well mod that to remote the headphone jack instead of modding the speakers.

That will give you (software dependent) the ability to mute the speakers when the headphone jack is unplugged to avoid blasting the world at high volume.

knoydart

904 posts

Ultimate Geek

Trusted

#431727 27-Jan-2011 10:12

Hi,

you might not need to go "smart" at all. You should be able to pick up 3.5mm sockets from Jaycar or DSE which have a change over switch in them. ie it breaks and make contacts when you plug in your head phones. A couple of leads, a bit of "strip board" and the socket and you'll be able to use any audio source as long it can drive your headphones and the input to the amplifier happily.

Cheers

Knoydart

Speedy885

182 posts

Master Geek

#431969 27-Jan-2011 21:38

knoydart: Hi,

you might not need to go "smart" at all. You should be able to pick up 3.5mm sockets from Jaycar or DSE which have a change over switch in them. ie it breaks and make contacts when you plug in your head phones. A couple of leads, a bit of "strip board" and the socket and you'll be able to use any audio source as long it can drive your headphones and the input to the amplifier happily.

Cheers

Knoydart

or even using a transistor and small relay to do the switching if a switching socket cant be found (DSE is USELESS for components these days) jaycar may have something though.

gzt

17105 posts

Uber Geek

Lifetime subscriber

#432023 27-Jan-2011 23:20

@mikelday - Gmail advertising gave me this a few weeks ago. Have not looked closely but prices seem reasonable:

http://www.mouser.co.nz/Catalog-PCB-Relays_558.aspx

Speedy885

182 posts

Master Geek

#432306 28-Jan-2011 17:05

looks interesting but you need more than a relay maybe a circuit like this is what OP needs:
http://i54.tinypic.com/2njaqhf.jpg Relay is a DPDT.

Note: i have not tested this but im sure it should work.

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Speedy885

182 posts

Master Geek

#432601 29-Jan-2011 16:57

Sorry i cant edit my first post but just to clarify where i wrote "stereo sockets" the part under it is actually part of the relay! Id written it in the wrong place LOL.