Microphone Wiring Advice Needed

[ehaughn]

I am installing a Garmin 2820 and would like to take advantage of using the J&M wired headset (microphone) using the cell phone feature.

Here are my thoughts.

Make a connector between the lower drivers cord, break out the microphone wires and connect them using a 2.5mm jack into the Garmin 2820. I would rather not create the connector and was wondering if anyone has any thoughts on how to do this?? Maybe there is a connection in the com system I can connect into?? I tried using the cell phone port and it does not work. The other issue with the connector is that I would not be able to use the intercomm. Reason being, both the microphone on the Garmin and J&M com system put out voltage and could damage the system.

I have created a prototype cable and it does work. The only issue is that only I can use the phone and not the passenger (since it is the wife, maybe not a bad idea, except she would be able to listen to the conversation and not be able to speak).

[ehaughn]

I am suprised I have received no responses.

Here is a diagram of what I am trying to do.

[Big_E]

Here's mine, http://www.sierra-mc.com/proddetail.asp?prod=JM%2DJCB03%2DCFRG

[ehaughn]

Any electronics gurus out there?

How can I block DC from going into another device? Does a diode provide this functionality??

[bruce2000ltc]

Any electronics gurus out there?

How can I block DC from going into another device? Does a diode provide this functionality??
I'm not an electronics Guru but.....
Diodes won't work in your diagram because the current to speakers and from microphones is not DC.

Bruce Hodges

[Bob]

Ok, where to start.
Let's make sure you wired the connector correctly for the intercom CELL phone jack.
the tip of the 2.5mm is the mic
the middle ring is Audio from the phone
the biggest ring at the base is Ground for both
I cheat and use a motorola H300 bluetooth headset with 2 isolation transformers to do the intercom end so I don't have to take the phone off my hip. then I just turn on the bluetooth headset function on the phone.
If you want to hard wire it, in the oddments case, just make a cable that is the same on both ends, tip to tip, ring to ring and ground to ground.
the audio coming from the Garmin is about 100 times louder than your mic you want to hook up to it, I.E. you would not hear a thing or your GPS whould blow you away!
Does this help?
I have a PDF that shows common hookups for Cell phones, GMRS/FRS radios, etc in the Files section.
Call me if it does not,
Bob Weir (707)799-9031

[Bob]

Any electronics gurus out there?

How can I block DC from going into another device? Does a diode provide this functionality??
You would use a capacitor for this. A capacitor passes AC only, DC wont go through. That is why you tie a capacitor from the positive side of the 12 volts to ground. It looks like nothing to DC but a noise signal like alternator noise is an AC like signal. Those see the Capacitor as a short to ground. Cool Eh? a 1-10uF cap with a rating of at least 16 Volts would fill the bill nicely. I am a little confused why you would hook up through the GPS.