I have a noka carkit which works quite well for my wifes Nokia
(My old phone
As many of you know nokia uses four pin plug for audio (plus a power plug)

On my Nokia Stereo Headset these are used for :
  • left
  • right
  • mic(flash for answer button)
  • earth (cos where would you be without earth!?)

In the carkit there is only one speaker so I dont think left/right are used.

Basic model Wasinaus's (planned) converter

3 pin 2.5mm male plug goes into treo
wires go from the three plugs to the appropriate places on a female 2.5mm 4pin socket.

  • audio
  • empty (no left chanel)
  • mic(flash for answer button??)
  • earth (cos where would you be without earth!?)

Voila a (hopefully) working car kit.


model 2 Wasinaus's (planned) converter

Basically emulating the seido stereo hands free by building in a switch so that the mic circut can be swiched out and a second audio circut switched in so that stero audio can be listened to from the treo untill the phone rings.
When it rings (ringtone per the seido or normal stereo headset comes through the phones speaker) flic the swich to put the mic in circut.. press the flash button and speak to your caller (always say "hello....its wasinaus here...." thats what my mother always told me to say)


Parts list

  • 1 small box to mount switches on (matchbox or slightly larger)
  • 1*female 4 pin socket 2.5mm (could mount this on box?)
  • 1*male 3 pin socket 2.5mm
  • some wire....
  • some solder
  • some shrinkwrap to make the cables look good
  • 2 way switch (for the advance option)
    (4 pole either A+B or B+C so you remove break one of the circuts at all times))
  • mommentory flash push button(for the advance option)
  • a couple of rubber grommet things to secure the box end of the cables.
  • some skill with a soldering iron (dont know where to get this?)

Parts list $20 ?? Australian I mean .....
Skill level required.....soldering iron and screwdriver.

Need to pull out the multi meter and measure the resistance on the handspring headset and the nokia carkit to make sure they are simmilar.
Also need to check the 4 pin audio plug in carkit is not powered itself (I dont think it is)

So apart from the challenge of putting this together can anyone see any major problems with this plan?

Looking forward to comments.