I want to plug my iPod which in turn supplies power to an external audio amp while sending iPod audio signal to same amp.
Is it possible to wire an 1/8" (3.5mm, mini) stereo jack in such a way that when the connector is inserted, a relay coil is actuated that powers on a car audio power amp? I have a 12V DC relay but how can I use the jack's internal switch to actuate the coil when the headphone jack's switch is essentially backward?
This is for a boat. The only solution I can come up with is to have the relay coil normally actuated but I think this would eventually drain the battery (I haven't done the math on that).
I have this Radio Shack version headphone jack with the internal SPDT but the switches are not isolated from the audio signal and are N.C.:
http://www.radioshack.com/product/index.jsp?productId=2103451 Surely designed this way so that the audio signal is passed to the big-speaker-amp when the headphones are disconnected.
(this is where the images were to my minijack diagram and my relay diagram…oh well…I'm a new user and this is clearly spam…)
Best Answer
You want jack "C" at the bottom of this link: http://en.wikipedia.org/wiki/Phone_connector_%28audio%29
The tip and sleeve switches are electrically isolated from the plug so signal is transmitted uninterrupted.
There are 1/4" jacks here (http://www.minute-man.com/acatalog/1_4__Stereo_Jacks.html) that do this. I'm sure they have 1/8" jacks that do the same thing, but I didn't look.
I was looking for the same thing, but for switching inputs based on whether the plug was inserted in the effects return on a tube guitar amp. Can't be puttin' that signal level into the common when someone has it in their hands!