Audio Circuit Hobby Project...Need Input...

Hello Everyone,
This is my first post here…Thanks for allowing me to join your forum…

I have an idea for an electronic audio hobby project that I would like to build. It’s kind of a specialized device that doesn’t seem to be available commercially, so I would like to design and build it myself, just for fun, and I’m asking for some help with the circuits because I don’t know much about that.

Basically, I envision a small box big enough to house a “AA” or “AAA” battery power supply and will have 2 Input jacks on one end and 1 Output jack on the other end.

Input 1 will be a 1/8 jack for an Ipod which will continuously play music…Input 2 will be a ¼ jack that will periodically produce an audio tone…Output 1 will be a ¼ headphone jack…

The basic operation will be, the Ipod ONLY will play music continuously into Input 1, through the box, and into the headphones at Output 1…When an audio tone of sufficient strength is heard through Input 2, the music from Input 1 will be cut off for a number of seconds, and then ONLY the audio tone from Input 2 will be heard through the headphones…After the predetermined amount of time, the device will switch back, and ONLY the music will be heard again…

I would like the device to have an on-off switch…A control to adjust the strength of Input 2 required to trigger the switch between Inputs 1 & 2…A control to adjust the amount of time Input 1 will remain silent (1 to 10 seconds)…And a volume control for Output 1 to the headphones…(The on-off switch could be included with any of the other controls)…

When the device is turned ON I would like it to operate as described above…When the device is turned OFF I would like the periodic tone from Input 2 to be heard through the headphones…(if possible)

I would like to build a larger sized prototype at first to proof the design, and then later make another usable model reducing the size as much as possible…

If anyone has any advice, ideas, or comments about how to start this project, I would enjoy hearing them…And if anyone knows of any existing plans that are similar to this idea I would enjoy seeing them…

Sorry for the long post…Thanks Everyone,
SanDiegoJoe

could you draw a picture of it.

Maybe I need to give a little more information about what this device is and how it will be used.

I'm an avid metal detectorist (that's right...one of those guys you see at the beach) and I've been doing it for years...I wear a large set of headphones and walk around swinging my machine waiting for it to "Beep" and tell me when to dig...Sometimes 10 or 15 minutes will go by between beeps...I think it would be cool to listen to music in the mean time, but I don't want to miss any "Beeps"...So my idea is to make a device that goes between my machine and my headphones...I would also plug in the Ipod and listen to music through my headphones...When the metal detector beeps, the Ipod would go silent, and I hear only the beeps...Once the detector stops beeping, a few seconds delay will pass and the Ipod comes back on...

Not sure if this is even possible but thought I would run it up the flagpole and see if anyone has any ideas how to make this work...

Here is a basic diagram/flowchart that I have so far...
Thanks,
SanDiegoJoe

Look in Google for VOX Circuit (voice operated switch) or Ducking Circuit (the music ducks its level when the announcer talks).

Thanks for the suggestions...

I did find a few Voice and/or Tone activated plans but I need to find a way to incorporate the delay into those circuits...

The ducking circuit is an interesting idea...Never heard of that before...Very much like what I'm looking for...So far I can only find some heavy duty DJ stuff...But it is quite adjustable with delay, volume, etc and I like that...It would be good to find something more portable or light weight...

If anyone knows where I can find some plans for a Ducking Circuit please let me know...I think that's the way I'm going to go if I can...

Thanks again,
SanDiegoJoe

You rectify and filter your control audio and use the resulting DC to turn on a Jfet attenuator in the signal path of the controlled audio. Then you have a ducking circuit.
Keep the audio at the drain of the Jfet at or below 100mV peak for low distortion. When two resistors feed half the signal level at the drain to the gate then the distortion is very low.