Switching a relay when an audio signal is received.

[gazzarose]

Hi guys, im a newbie to the forum so hi.

Im part way through a project to fit a portable sat nav permanantly into my car. Ive sorted the mounting and the power, but as the sat nav will now be inside the dash, the sound will be hard to hear. My satnav also has the ability for bluetooth calls, so need decent sound for that. My plan is to play the sound through either all or just one of the car speakers, similar to how it is done with Parrot handsfree kits and the like. My car is a Lexus IS200 with the amp seperate fromt the head unit, so I can tap into that. I just need a way to switch between stereo and satnav automatcally when guidance instructions come through.

I was thinking of a relay that is switched when it receives a signal from the headphone jack of the sat nav, with a delay timer to stop it switching back and for between words.

I've got an electronics back ground having done it in school, and getting part way through an electronic degree. I can do the timer and the relay, but its just the trigger I can't figure out. Even just a shove in the right direction might be enough, although a circuit diagram would be even better.

Sorry for the long first post,

Thanks in advance

Gareth

 

[MrDEB]

why not just connect to the sat nav?

it has a speaker in it.
just disconnect the internal speaker (measure impedance) then connect to your audio system speakers (measure impudence first)
just a place to start.
might be the easiest??

 

[Externet]

it has a speaker in it.
just disconnect the internal speaker (measure impedance) then connect to your audio system speakers (measure impudence first)
just a place to start.
might be the easiest??

Whaaaat ? The stereo will blow the SatNav audio output stage.
Better use a separate spare speaker-amplifier like the ones for PC audio. Search for vox schematics.

 

[jimlovell777]

This is just the nudge you requested, if you'd like more info or help let us know.

**broken link removed**