Narrowing my search re: signal sensing

[Kgveteran]

How would i build a circuit to sense the signal of an audio signal, then close the contacts of a relay from normally open to closed.

Im a total noob with circuit design, but could follow a schematic.

My goal would mate this with a smart strip that has just such a hookup and allow for a automated sound system in my garage.

 

[MikeMl]

What audio level?
What is the output impedance of the audio source?
What are the specs for the relay you want to drive?
What power supply do you have to run this?
What is the relay switching?

 

[crutschow]

Another question:
Do you need the relay to stay closed if there is a short break in the sound?

 

[Kgveteran]

What audio level?
What is the output impedance of the audio source?
What are the specs for the relay you want to drive?
What power supply do you have to run this?
What is the relay switching?

The audio signal out of an Apple Airport Express. No idea the impedence.

The relay would be connected to a smart powerstrip. All my three components would be connected to the power strip.

 

[Kgveteran]

Another question:
Do you need the relay to stay closed if there is a short break in the sound?

YES !!! It needs to be no different from a signal sensing circuit in a piece of gear like a Sonance amplifier that senses an audio signal and turns on. I dont have the specs from the power strip....

I wish it was a separate board in one of those amps, i could pick up a junk one and harvest it. Seems to be onboard one of the preamp boards.

 

[Kgveteran]

LRG series - "Creative Applications" Smart Strip (Custom Build)
Another new model of the Smart Strip series is the LRG. When you're using the Smart Strip not just to plug stuff into, but as a piece of something you're creating, we've come up with a nifty feature. A small standard 2 wire connector on the side of the Smart Strip that when you short the connector together, it turns on the switched outlets; unshort it & it turns them off; for the hobbyist, it's a dream come true. This control signal circuit is similar to that which modern computers use which is a low voltage, low current signal to control your 120 VAC high current devices. Remember, however, that the control outlet will also still work exactly like any other Smart Strip so you can be creative in how you use this new feature. As with any other Smartstrip, the outstanding surge protection and power ‘scrubbing' ability will extend the lifespan of every electrical device plugged into it.

Here's a blurb from the smart strip add.....

 

[Kgveteran]

Here are some specs on the AE

Looking at the performance of its analog output, the maximum output level was 1.53V, 2.3dB lower than the CD standard's 2V, and the AE inverted signal polarity. The output impedance was a usefully low 15 ohms across the audioband

I think we're getting somewhere with these specs. I can see the 1.5v tripping a relay and closing contacts on the power strip, but how to work in the delay of at least 10 minutes or so......would this little device require power.....