Leads and Sockets for modifying my Garmin i3!

Chipstix · Occasional Visitor Joined: Apr 13, 2006 Posts: 39

Hi All,

I am trying to source components to enable me to fit an audio socket onto my SatNav unit.

I would like to fit either a 2.5mm of 3.5mm socket (drill hole in plastic housing and fit on. Like this....[thats not my unit, or hand by the way!!!]

The output of this needs to go into a 4-pole stereo 3.5mm socket on my autocom unit.

I am looking for:
a) suitable socket to fit to SatNav unit
b) suitable lead

The socket needs to be switched, so that when a 3.5mm jack is inserted, the sound is cut from the SatNav internal speaker. Any advice, have had a good look on Maplin, ebay, rs but not found quite the right stuff......

Cheers, C.

mikealder · Posted: Fri Jan 18, 2008 3:38 pm Post subject:

You shouldn't need a 4 pole connection for doing this, the device has a single speaker so take the output and connect it to both left and right side inputs on the autocomm plug.

A three pole switched socket like This should do the trick, the matching plugs can also be found on the same web site.

The switched sockets from Maplins are only PCB mount style which would be very difficult to secure to the device.

If and when you do this please make sure you have the volume set to minimum on the i3 prior to connection as driving an amp input is far less of a load than the speaker the i3 is used to powering - Mike

Chipstix · Occasional Visitor Joined: Apr 13, 2006 Posts: 39

mikealder · Posted: Fri Jan 18, 2008 4:23 pm Post subject:

You will have to remove the two wires from the speaker in the i3 and solder them to the common side of the jack socket, one wire needs to go to both the left and right connections on the socket.
Then connect the speaker back to the switched side of the socket, this way when there is no plug inserted the audio is routed to the speaker - it would be best to work out which contact does what with a multi-meter when you have got the socket to be honest - Mike

Chipstix · Occasional Visitor Joined: Apr 13, 2006 Posts: 39

I basically get it. Can't visualise how many solder tabs there will be on the socket, and there is no schematic/datasheet I can see on Farnell but I know what I'm aiming for, and I have a multimeter!

Do you think it it worth fitting a resistor somewhere to build up the impedance of the non-speaker output. I can imagine forgetting to reduce the volume before connecting to the autocom, and wouldn't want to damage the autocom......

Thanks,

mikealder · Posted: Fri Jan 18, 2008 8:39 pm Post subject:

I would expect 5 terminals on the socket, one for the common point as it probably isn't switched and a pair of contacts for Left and Right, an input (which is wired to the i3 sound output) and output terminals (which goes to the speaker).

As for increasing the impedance it won't work unless you fit the resistance into the lead between the i3 and the Comm unit, otherwise it would attenuate the sound of the built in speaker - as for a value I wouldn't have a clue, you might need to do some SOT experiments (Select On Test) once its up and running - Mike

Chipstix · Occasional Visitor Joined: Apr 13, 2006 Posts: 39

For the benefit of anyone reading this in the future, I think this is my list of components:

(I'm also making up a cigarette lighter socket onto a radio-control car style battery pack connector which I will carry with the bike, and if I need to charge a mobile phone etc, I will connect this to the existing Optimate charger lead which is connected to the bike's battery)

The Garmin will be hardwired (i.e. will break open the cigarette lighter plug, but obviously retain the electronics, and replace the fuse for an inline one)

For GPS, HF78K from Maplin: http://www.maplin.co.uk/Module.aspx?TabID=1&ModuleNo=1133 - £0.79

And then the Autocom 1294 lead (elusive 2.5 mono to 3.5 stereo lead, Autocom is the only place I can find who do make them) from HSL - £5.00

For connecting Autocom and GPS to power, 2 sets of SWP2 from http://www.vehicle-wiring-products.eu/VWP-onlinestore/connectors/multiconnectors.php - £3.94 a set

For the lighter socket adapter, either GZ98G or GZ99H from Maplin depending on which is my bike (need to check): http://www.maplin.co.uk/Module.aspx?ModuleNo=11474 - £1.89

Then a cigarette socket: either 41829 or 42248 (advantage: sealed cable into the socket, socket cover, pre-wired - just chop the croc clips off) from http://www.vehicle-wiring-products.eu/VWP-onlinestore/switches/12vacc.php - £1.32 or £3.85

Fuse holders (if required): FH580 from http://www.vehicle-wiring-products.eu/VWP-onlinestore/fuses/holders1.php - £2.35 each

Snudge · Posted: Fri Jan 25, 2008 9:40 am Post subject:

Chips - this is interesting to me so can you keep this thread updated with your progress on this one please? I've got a TomTom One XL which I intend fitting to my bike but never thought I could have sound. I haven't looked inside to see if there is room for the plug to be fitted so don't know if it's possible on my model.
This is good stuff - thanks.

Chipstix · Occasional Visitor Joined: Apr 13, 2006 Posts: 39

Hi Snudge,

Will do.

I may get down to Maplin this weekend to pick up a few of the bits and bobs. Also need to try to see what the input impedance of the autocom unit is. Be interesting to see how it compares with the impedance of a pair of headphones, as people have been doing that (presumably) without blowing headphones....

Just that I can't see myself remembering to keep the volume down every time I connect to the autocom.....

Cheers, C.

welshgasman · Regular Visitor Joined: Apr 17, 2006 Posts: 122

FWIW I just used a Sony earpiece headphones at first, then bought some Sennhieser earphones, which turned out to be knock off, but actually sound louder than the Sonys so I could turn the volume down.

I installed mine in a small Really Useful Box that I picked up in Maplins, surrounded by some foam. I had the 3.5mm socket mounted on this box, and just plug into this each time. Ouput is mono only.

Chipstix · Occasional Visitor Joined: Apr 13, 2006 Posts: 39

I have installed the autocom headsets into mine and my wife's lids. Have done a quick test in the house (not been out on the bike yet), and am hugely impressed with the quality.

Next job will be hard wiring power for the autocom onto the bike, but I may try to get to maplin for the bits for modding the i3 this week. Autocom reminded me that if I choose to try and power the i3 from the bike too, I will need to include an isolator between the i3 and the autocom, as the headphone lead will form a ground loop. May just stick with high capacity NiMH AAs to make my life easier.

So, not much progress but will keep you posted.....

C.

welshgasman · Regular Visitor Joined: Apr 17, 2006 Posts: 122

I always carry a spare set of batteries when out.

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