Is there a 3.5mm female stereo jack that will detect when a cable is connected?

[hoffsta]

I'm building a project that has an always-connected audio source to the amp and I'd like to add a 3.5mm stereo jack, auxiliary input that automatically takes over and disconnects the default input signal. Unplugging would restore the signal. I was thinking that if there were a female jack that closed a circuit on a separate set of pins from the audio signal when a cable is inserted it could be used to trigger a relay. This would need to be a panel mount jack. Anyone know if such a product exists? If not, what would be the most ideal way to accomplish this configuration? Thanks!

 

[Enzo]

There may be, but I don't know of 3.5mm jacks with the extra contacts. But certainly 1/4" TRS jacks come with extra contacts, and it would be simple enough to stick a 3.5mmfemal to 1/4male TRS adaptor on your cable end, and use a 1/4" jack.

You could also get fancy and wire the extra input through a sensing circuit that senses the presence of signal at that input and takes over. Like a ducking circuit in a PA system that quiets the music when an announcement is made.

 

[DUG]

Some 3.5 mm jacks have switches that will let you know when there is a connector in place.

http://www.digikey.com/scripts/dkse...t=0&page=1&quantity=0&ptm=0&fid=0&pageSize=25

Use this to control a signal level relay.

Simple.

🙂

 

[hoffsta]

Thanks for the replies.

DUG, your link returned 180 results from digikey! I'm not exactly sure what I'm looking for in the specs as I'm really new to this stuff. But this one looks like a pretty safe bet: SJ1-3534 has three conductors, four contacts, one tip switch.
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Is it what I'm looking for? Do these type of switches engage when the plug is inserted or when voltage is passed through?

As for the relay, I'm not really sure what kind of specs to look for. Input will be from iPod/Smartphone headphone jack levels so probably less than one volt. Can anyone point me to an example product of what I'm looking for? Here's a link to digikey's signal relays:
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Thanks again!

 

[hoffsta]

On the relay, I'm thinking DPST NC is the correct format but I don't know what else to look for.

 

[DUG]

Look at the data sheet for this one:

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Use pins 4,5 to run the relay.

http://www.cui.com/product/resource/sj-3506-smt.pdf

Pick your coil voltage:

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Great little signal relays.

Use a diode for fly-back suppression. (if you don't know how, look it up)

Have fun.

🙂

 

[gmphadte]

If both the inputs are connected to the same circuit, but only through a switch, then there is a 3.5mm socket available that disconnects the signal from other input. This was done in mic and aux connection in cassette recorders. Such socket will have 5 connections ane of which is gnd.

Gajanan Phadte

something like this
http://www.taydaelectronics.com/6-35mm-1-4-stereo-insulated-switched-socket-jack-solder-lugs.html