Stereo-ish wiring question

[idosubaru]

Have an inline FM transmitter in the XT6 and would like it to turn on when the phone is plugged into the jack. Is that possible?

 

I'm not sure what kind of signal the music is that plays through those lines but I imagine it's rather small or light duty coming out of my phone?

 

I'm wondering if I could tap into those lines and have it trip a relay to turn the transmitter on when I plug the jack into the phone? Can relays work on a signal that weak?

[Scoobywagon]

Yes. You can do that, but you'll need another part. DEI makes an amplifier turn-on part that is supposed to be used when adding an amp to a factory stereo with no switched power out. It detects an incoming audio signal and turns on a relay that gives you +12v. It isn't rated for much current, though, so what I'd do is I'd use that DEI part and use it to drive a Bosch-style relay and have the relay actually supply power to the FM Modulator.

 

It occurs to me also that many of the wired FM modulators have remote switches. Is that the case with yours? If so, you can simply replace the switch with the output from the DEI part and wire the modulator as normal.

[idosubaru]

Yeah, I just have the power and ground wired to a switch.

 

Thanks for the suggestion on the DEI part, that's awesome, sounds like exactly what I'm looking for.

 

*** Looks like this is what you're referring too?

http://www.sonicelectronix.com/item_11263_Directed+55000+.html

 

Detects as little as 5 volts - i wonder what the output is of my phone? Guess I can try to measure that somehow.

[Scoobywagon]

That's the part!

 

Don't know about a phone, but we've managed to get it to work with things like portable CD players.

[idosubaru]

someone on the XT boards said it's probably not sensitive enough to trigger with a simple audio signal, sounds like it does?

 

they also suggested it will "cut on and off", like during quiet parts or between songs so to speak it won't have a signal so will turn off?

 

it's so cheap i might try it after your next response.

[Scoobywagon]

I'm not sure what they meant by "simple audio signal". That's pretty much EXACTLY what it was designed for...sensing incoming audio. The question REALLY is whether or not your phone produces sufficient voltage to trigger it.

 

As far as the triggering on and off...never noticed it do that before. Even when you have a silent part, like a long pause between songs, there is still noise. Also, if I recall correctly, the unit does some filtering for that. If it decides that there's no audio, it'll wait a little bit before it turns off.

 

When you do the install, be sure to take note of the current requirements for the FM modulator as well as the current capacity of the trigger. You may need to add a relay to this.

 

Let us know how it works out for you.