Tie GPS to Intercom - input from electronics gurus please

[MiCarl]

I want to tie the audio output from a navigation system to the audio system of the motorcycle. It needs to mute the radio when it talks. Since we always use headsets the audio through the headsets is the ideal solution.

 

Essentially, I want it to act like a 3rd mic on the intercom. That way it mutes the radio and we hear it through the headsets.

 

I'm wondering if I can't piggy back it onto one of the headset mics using a circuit similar to the one in the drawing.

 

Sure would appreciate input from the electronics wizards.

Edited February 10, 2010 by MiCarl

[Eck]

Not so sure this is what your looking for but..her are some detailed instructions to add a aux splitter.

(provided by Squidley).

 

http://www.venturerider.org/forum/showthread.php?t=3905

 

 

[painterman67]

talk to buddy rich he makes a cable and can probably walk you through it.

 

 

 

David

[Eck]

talk to buddy rich he makes a cable and can probably walk you through it.

 

 

 

detailed instructions provided by Buddy is located in the tech section under 2nd gen, radio

[Thom]

Carl , hope somebody can figger something , maybe a VOX type sw. , i have been keeping up with the thread " tape deck "

Carl needs the info for a 1st gen not a 2nd , i wish Buddy made a cable for us .

[scotty]

I am no guru but rather just thinking out loud...

Could you tie the audio into the CB plug on the amp and use something like a opamp to trigger the 6 volts to mute the radio?

Scotty

[MiCarl]

I am no guru but rather just thinking out loud...

Could you tie the audio into the CB plug on the amp and use something like a opamp to trigger the 6 volts to mute the radio?

Scotty

 

I'd thought about that but it seems like it'd be much more complicated. Especially when you consider you'd have to damp the thing somehow so it didn't cut out between words.

[Marcarl]

Mine owrks just fine,,,, Mother made a cable for me,,,, send him a PM and ask him how it's done. Works quite simple, plugs into the cassett deck input in the amp and comes with a switch. I think it does everything it's supposed to.

Carl

[painterman67]

Carl , hope somebody can figger something , maybe a VOX type sw. , i have been keeping up with the thread " tape deck "

Carl needs the info for a 1st gen not a 2nd , i wish Buddy made a cable for us .

 

 

Thats what I been trying to tell you. get in touch with buddy. he does make a cable for the first gens. I think it is a litle more expensive, but he makes it.

 

 

 

DAvid

[MiCarl]

Carl , hope somebody can figger something , maybe a VOX type sw. , i have been keeping up with the thread " tape deck "

Carl needs the info for a 1st gen not a 2nd , i wish Buddy made a cable for us .

 

I've got a solution that seems to be working. GPS lady comes over the intercom without interfering with the normal intercom operation.

 

For some reason she does not mute the radio, however if I plug a transistor radio into the cord it will mute the motorcycle radio. Apparently the synthesized voice doesn't have the right characteristics to mute the radio. It does have enough gain though that it comes in clear even with the radio turned up.

 

Once I confirm that it doesn't pick up engine noise I'll post the drawing.

[MiCarl]

No engine noise, so it's a success.

 

All the parts are available at RadioShack:

 

274-284 1/8" Stereo Phone Plug (2 Pack)

278-513 50-Ft. Audio Cable

271-1105 47 ohm 1/2W 5% Carbon Film Resistor pk/5

271-1126 10K ohm 1/2W 5% Carbon Film Resistor pk/5

 

I also used some heat shrink tubing and electrical tape.

 

I connected the cable to the motorcycle at the passenger head set jack because it is easy to get to. Motorcycle pin out available in THIS THREAD.

 

The headphone jack on my GPS is not effected by the GPS volume control (of course there is 0 documentation). My conclusion is that it is a line level output, although it will drive headphones.

 

With the 10K resistor it booms through the intercom pretty good. Replacing the 10K with a 100K resistor was a bit on the weak side. With a transistor radio I can easily over drive the intercom input with the 10K resistor, which was not an issue with the 100K.

 

Overall, a 15K resistor (I didn't have one to test) might be a better choice.

 

My recommendation for anyone trying this would be to start with a 15K resistor and the GPS volume turned down. If you can't get enough volume turning the GPS up fall back to the 10K.

 

The colors in the diagram match the RadioShack cable, with the black being the braid. The goofy thing on the left is the phone plug.

[Terry Richardson]

hey Squid I know this is for a 2nd Gen, any idea if there is a simular arrangement in a 1st gen?

 

 

Not so sure this is what your looking for but..her are some detailed instructions to add a aux splitter.

(provided by Squidley).

 

http://www.venturerider.org/forum/showthread.php?t=3905

 

 

[MiCarl]

Installed a GPS power cord on the motorcycle so I wouldn't be limited by the four hour battery life of the GPS. That made so much noise in the intercom it sounded like listening to an old AM radio, during a thunderstorm, while running the vacuum cleaner.

 

After puzzling over it a bit I realized the power cord was probably creating a ground loop problem. The solution was to add an isolation transformer from the friendly neighborhood RadioShack (273-1374 1:1 Isolation Transformer).

 

I suspect a ground loop would be a problem for any equipment powered by the motorcycle electrical system.

 

New Schematic:

[Herb In Texas]

I suspect this is for a 1st gen, but is it the same for a second gen? I just put on a garmin 765t. I went to radio Shack and got the stuff to split the aux under the fairing. But it just aint what I was hoping to get done. You can only hear the G chick on AUX and not play the radio. Sure would like it if this could be done on a second gen. Any help out there. And to Micarl, do you want to make up a cable that I could just splice into my I com system?

[in flagrante]

You might try giving these guys a call -- Kennedy Technology Group

 

http://cellset.com/Motorcycleitems.html

 

I haven't tried them but, according to a Yammi dealer, I heard that they have the wires necessary to integrate a Garmin GPS to the intercom system for the Venture.

 

Curious if anyone's every tried Kennedy for anything????

[kbran]

I've had the cell set to have voice and cell phone thru the tomtom rider gps for about 3 years now. Works fine.

[MiCarl]

I suspect this is for a 1st gen, but is it the same for a second gen? I just put on a garmin 765t. I went to radio Shack and got the stuff to split the aux under the fairing. But it just aint what I was hoping to get done. You can only hear the G chick on AUX and not play the radio. Sure would like it if this could be done on a second gen. Any help out there. And to Micarl, do you want to make up a cable that I could just splice into my I com system?

 

I did make it for a 1st gen but I'd think it would work on a 2nd gen. It essentially piggybacks on the headset mic and the 2nd gen uses the same headsets.

 

I'm more concerned the different model of GPS (I have a Navigon) would have a different output level necessitating a different resister.

 

The lady on mine (only 1 voice in English) doesn't trip the radio mute except for the end of the word "destination". Apparently that circuitry on the 1st gen is only sensitive to lower pitches. That's a bit of a drawback, but unless the radio is really cranked I can tell what she says.

 

Right now I really don't have time to make one. Catch me late in the fall and you just might talk me into making one.

[Herb In Texas]

:thumbsup2:Thanks Carl,

I am not sure there is a mute "feature" on the second gen. If I understand the mute Your talking about is when you passenger speaks. The radio cuts out. Don't happen on mine. I have to balance between the two. Keep the radio low enough I can hear Dawn and still keep up with Beck. So the mute thing is not a concern of mine. Multi tasking and listening to several sources at once is second nature. I believe I will try to make up this cable. per your schematic. Confuses me though it apears that the 2 47 ohm resistors are conected to all three wires from the 1/8 plug then the isolation transformer completetes thje circuit a third time. I am not an electrical engineer but I do have a good bit of practical experiance. The resisistors will pass current both ways not like a diode which will only pass one direction, Right? Why don't it burn to the ground? As far as soldering up all the parts and patching into the system on the bike I have no problem I just want to understand. Going to Radio Shack tomorrow and get all the stuff. I can put it together like I read the drawing. I guess I just need clarificatin that I am reading it correctly. I see a "dot" Between the resistor conections on all the leads coming from the plug. A DOT TO ME SIGNIFIES CONNECTED. If it were a cross over a little horse shoe would be there. please get back to me before i set fire to the Mighty stead.

Thanks

Herb

[MiCarl]

Dots are connections. I did not use the Us where wires don't connect. They just cross each other.

 

No diodes. Only resistors (audio is AC).

 

The 47 ohm resistors simulate a stereo headset load. The purpose is to protect the output amp on the GPS box, although the power levels are low enough it's probably not an issue. They do bleed off most of the output power of the GPS, without them you'd need more than 10K ohms on the 3rd resistor. As far as "burn"ing it to ground, that's what the braid on the cable is.

 

You are correct that the isolation transformer (or the motorcycle intercom system if the transformer isn't used) completes one audio channel a second time. The 10K resistor severely limits the power pushed into the mic circuit on the intercom. Condenser mics produce a tiny fraction (on the order of 1/10,000) of the power needed for headphones. Running all that power into the mic circuit would certainally result in distortion and probably damage the intercom circuitry.

 

With the 10K resistor on the parallel circuit that GPS audio channel sees 46.78 Ohms load rather than the 47 ohms on the other channel. Negligible to the GPS and actually less than the 5% tollerance on the 47 ohm resistor anyhow.

 

The isolation transformer separates the GPS ground from the motorcycle ground. This is necessary because the noise put on the GPS ground by the charging circuit gets amplified some 10,000 times by the intercom. In other words, it's really loud!

 

BTW, if you make sure to have the matching transformer on the leg that goes to the tip of the plug your cable will work with a mono source. If it's on the other leg (to the first ring) it won't pick up audio from a mono source.

 

Anyhow, make it just like the diagram. Try it before you seal all the components up. The idea is to have the GPS audio just about the same level as you get from your mics. You might need to change that 10K resistor up or down to get it matched. Otherwise you might have to turn the intercom volume up so high that the passenger blows your brains out when she talks or vice versa. My best guess though is that the 10K will be just fine.

 

On mine there is about 18" of cable from the passenger headset plug to the resistors and isolation transformer. That puts that package of components under the seat. Then there is a longer cable to the headphone plug that connects to the GPS. The individual components have heat shrink over them and are folded back over the cable. There is heat shrink over the whole bundle. This results in a package about 3/4" in diameter and 2" long.

[painterman67]

I suspect this is for a 1st gen, but is it the same for a second gen? I just put on a garmin 765t. I went to radio Shack and got the stuff to split the aux under the fairing. But it just aint what I was hoping to get done. You can only hear the G chick on AUX and not play the radio. Sure would like it if this could be done on a second gen. Any help out there. And to Micarl, do you want to make up a cable that I could just splice into my I com system?

 

 

 

hey HERB

 

PM BUddyrich,

 

He makes a cable for the second gens that is supposed to be plug and play.

 

 

David

[Herb In Texas]

Thanks Painterman, Buddy's cable (as I understand) allows blue tooth through the Zumo GPS for cell phone use. The Garmin does not have an input jack for an external mike, only has a mic on the face of the unit to use blue tooth.

Thanks X 10 to Micarl. I understand now! I was not able to go to Radio shack yesterday as my plans had to be rearanged. Had to attend a competitive trail horse competition instead. Had a great time BTW. Will stop on the way home tomorrow. Whoda thunk A/C circuit. This site is great. ya'll have my eternal respect for your scents of comunity and helping a brother rider out. Good on Ya!

Thanks again Herb

[Wizard765]

Herb:

 

You're 765T I believe has a mic input on the mount. I know my 785T does as well. You are right it is not on the GPS itself. I had some messing around to do to get mine attached to the bike using the garmin mount so that I could have mic input.

 

Wayne

[Herb In Texas]

Man a whole nother kettle of fish. how did you find out about the line in from the mount. the book with the 765 ain't worth a cr---. you would think if they thought that far ahead they would want us to know that they made the feature availible. Even having a stable full of acc. to go with.

[Wizard765]

My 785T has it and my friend bought the 765T for less money and ALL the same features.. His was the better buy. Even has free for life FM traffic. Mine as MSN Traffic I have to pay for... I'm jealous LOL:rotf:

[Herb In Texas]

MIne has the FM traffic as well. Kinda cool. I e-mailed garimn support last night about tapping into the cable that runs to the mount will see what they respond with. But thinking about it I wonder if the zumo and garmin cables match? If they do then buddy's cable may be just the ticket. Any guesses out there. Is zumo a garmin product? Better google it and see. Here I Go.