auto mobile phone mute

armoured !! · 11-26-2003, 05:37 AM

hi ppl !!

it's been quite some time since my last posting, but that doesnt mean I stopped visiting this great forum!!

anyways, I have just installed my new sound system which includes a Cerwin Vega Stealth 12" sub with box .... i love it

Now, my head unit is an Aiwa CDC-R917M which i find great for my needs - it has a nice simple display, no skipping, and it hides face when turned off. Now it also has a wire at the rear - a brown one - which is called telephone mute. On the instructions it says that it is used to automatically mute the sound when the phone (in its hands free car kit) rings. I think that this wire obviously accepts some sort of voltage signal in, just as the (blue) power on of the amp.

My question is: Does anyone know what this voltage is? And does anyone has any idea of how to make this possible with out installing a hands free kit ??

Ed ....

Enforcer · 11-26-2003, 06:06 AM

it vasries from system to system, you need to check the instruction book. mine has to be grounded to be activated, which my nokia car kit does so I have just connected the two and it works fine, my headunit also has a phone speaker input so now the phone goes through the car speakers.

skassama · 11-26-2003, 08:03 AM

just use a fuse in the middle and ground it for muting. Generally all car phones give out a -ve, ie 0 volt signal.

It works very well with my bose and I300 car kit.

armoured !! · 11-26-2003, 12:09 PM

ok, i will try and see what happens, i hope that the fuse works well if needed !!

EBJUSTIN · 11-26-2003, 12:21 PM

Quote: Originally Posted by armoured !!

ok, i will try and see what happens, i hope that the fuse works well if needed !!

The audio mute input on your radio has a weak internal pull up resistor, and the radio will mute when this line is pulled to ground. The cellular mute wire on your hands free device is high impedance or 'open circuit' when the phone is NOT in a call. When the phone rings or is in a call the hands free device will ground the cellular mute wire which will easily overdrive the weak pullup resistor on the radio and the radio will mute.

My setup is headunitless so I had to use a relay...I used the cellular mute from my cellport as the ground for the relay hence the relay only activates (wired to turn off remote signal to eq) when my cellport grounds the cellular mute wire. This works very well

armoured !! · 11-28-2003, 04:24 AM

hello again -

just to tell you that I tried your suggestions and the method of grounding the wire worked well. As usual, this forum with its helpful members helped me once more with my in car entertainment setup !!! thanks

My next step is now to get one of those things that are battery operated and flash when they detect radiation from a mobile phone, to make it activate a relay which grounds that wire ...

if anyone has any suggestions, i'd be happy to hear from you!

Ed...

Spaghetti · 11-28-2003, 04:50 AM

I used to have one of those flashy things that detect when the phone's giving off a signal- basically they don't work! Well, ok- they do, but because you're using a cellular network the phone will always be roaming between masts and checking for signals and the device will always be going off. It'll do this every so often even if you're not moving... What were you hoping to hook the relay up to anyway?

armoured !! · 11-28-2003, 05:33 AM

um well i really dont know - i was thinking that some sort of relay could be used to ground the mute signal wire from the head unit whenever that 'thing' flashes off.

about those random flashing you're right, however i am willing to try it - it's not something expensive and i really need it cos i never hear my mobile phone when the sound is REALLY on !!!!!

unfortunately im not very electronics oriented, im more into software and any ideas will prove to be useful ....

Enforcer · 11-28-2003, 05:42 AM

Get a car kit

armoured !! · 11-28-2003, 06:19 AM

Quote: Originally Posted by Enforcer

Get a car kit

my intention is to have ANY mobile ANYWHERE in the car. And I hate to have the mobile phone sticking up my my dash. Plus my car has a place where to place it and i would like to keep it there Plus I like the challenge of doing things myself - like most people here, I think

Ed ...

Spaghetti · 11-28-2003, 06:45 AM

Is your phone bluetooth compatible? If not, get one! There are loads of bluetooth kits out there: hard-wired, battery-operated portable, earpiece, and plug and plays. As for ANY phone, well ANY bluetooth phone would work. And if you REALLY want to do your own hack, you could get a bluetooth dongle and program your own interface to the computer. Although I suspect this would be pretty damn hard.....

JeeP-3 · 11-28-2003, 11:02 AM

That is a good idea but experiment with the sensitivity of the device you're using to activate it. I was just looking in the shop here in town and they now make pens with flashing LED's when your phone goes off in your pocket, so no one in your meetings knows your phone is ringing except for the fact that your pen starts flashing randomly...

But the thing is you don't want the thing to be activated by someone in the next car... Just make sure it's one with a small range / low sensitivity.

deadweasel · 11-30-2003, 06:52 PM

You know, I would be tickled to figure out how Nokia works their accesories connections, so that I could connect my phone to the computer as well. I figure that I could hook it up so that at the touch of a button on the screen, the system pauses whatever sound it's playing and picks up the phone, transferring input from the mic (be it ear mount or visor mount) to the phone, as well as the audio output out to the soundcard for transfer to the car speakers.

I just realized how bad I'm getting about this. You know, I should just go out right now and just start embedding car wires into my arms. Which leads me to start thinking about mentally controlled driving systems! Yeah, I can see it now....

"wow, that chick in that car over there is HOT!!"
*Car overheats*
"****."

Wait, what were we talking about again?